# Wave Optics Questions

We provide wave optics practice exercises, instructions, and a learning material that allows learners to study outside of the classroom. We focus on wave optics skills mastery so, below you will get all questions that are also asking in the competition exam beside that classroom. #### List of wave optics Questions

Question NoQuestionsClass
1When the light is incident at the polarizing angle on transparent medium, then the completely polarized light is
A. refracted light
B. reflected light
c. refracted and reflected light
D. neither reflected nor refracted light
12
2The light beams of intensities in the
ratio of 9: 1 are allowed to interfere.
What will be the ratio of the intensities
of maxima and minima?
A . 3: 1
B. 4: 1
c. 25: 9
D. 81: 1
12
3With a monochromatic light, the fringe-
width obtained in a Young’s double slit
experiment is ( 0.133 mathrm{cm} . ) The whole setup is immersed in water of refractive index 1.33 , then the new fringe-width is
A. ( 0.133 mathrm{cm} )
B. 0.1 ( mathrm{cm} )
c. ( 1.33 times 1.33 mathrm{cm} )
D. ( frac{1.33}{2} mathrm{cm} )
12
4Two waves are said to have destructive
interference if
A. their frequencies are same
B. their frequencies are doubled
c. the phase difference is same
D. the phase difference is ( 180^{circ} )
12
5011
28. In Young’s double-slit experiment, the separation between
two coherent sources S, and S, is d and the distance
between the source and screen is D. In the interference
pattern, it is found that exactly in front of one slit, there
occurs a minimum. Then the possible wavelengths used
in the experiment are
d d d²
d d d
(a) 2 =-
” D’3D’ 5D
m d d d²
(c) 2 = nsnin (d) 2 = 30 D’U
(b) 2 =
50’9D
11.
12
6Two sound speakers are driven in phase by an audio amplifier at frequency ( 600 H z . ) The speed of sound is ( 340 m / s ) The speakers are on the ( y ) -axis, one at
( boldsymbol{y}=+1.0 boldsymbol{m} ) and the other at ( boldsymbol{y}= )
( -1.0 m . ) A listener begins at ( y=0 ) and
walks along a line parallel to the ( y ) -axis at a very large distance ( x ) away. At ( frac{theta}{2} ) angle she will first hear a maximum
( left(operatorname{after} 0^{circ}right) ) sound intensity. Find ( theta: )
12
75. The wavefront of a light beam is given by the equation
x + 2y + 3x = c (where c is arbitrary constant), then the
angle made by the direction of light with the y-axis is
(a) cos’ T
(b) sin
(c) cos
vía
(d) sint ha
12
8The phase change in reflected wave,
when light wave suffers reflection at the interface from air to glass is
A .
в. ( frac{pi}{2} )
( c . pi )
D. ( 2 pi )
12
9Huygens principle of secondary waves
A. allow us to find the focal length of a thick convex lens.
B. give us the magnifying power of the microscope.
C. is a geometrical method to find, the position of a wave front
D. is used to determine the velocity of light.
12
10Two circularly shaped linear polarisers are placed coaxially. The transmission
axis of the first polarizer is at ( 30^{circ} ) from
the vertical while the second one is at
( 60^{circ}, ) both in the clockwise sense. If an
unpolarised beam of light of intensity ( I=20 W / m^{2} ) is incident on this pair of
polarisers, then the intensities ( I_{1} ) and ( I_{2} )
transmitted by the first and the second polarisers, respectively, will be close to.
A ( cdot I_{1}=10.0 W / m^{2} ) and ( I_{2}=7.5 W / m^{2} )
B . ( I_{1}=20 W / m^{2} ) and ( I_{2}=15 W / m^{2} )
C ( . I_{1}=10.0 W / m^{2} ) and ( I_{2}=8.6 W / m^{2} )
D. ( I_{1}=15.0 W / m^{2} ) and ( I_{2}=0.0 W / m^{2} )
12
1114. The speed of light in the medium is
(a) minimum on the axis of the beam
(b) the same everywhere in the beam
(c) directly proportional to the intensity I
(d) maximum on the axis of the beam
12
12he slits are 2 mm
mum distance from
2 m from the
5. In a Young’s double slit experiment, the slits are
apart and are illuminated with a mixture of two wavele
20 = 750 nm and 2 = 900 nm. The minimum distan
the common central bright fringe on a screen 2 m fron
slits where a bright fringe from one interference pa
coincides with a bright fringe from the other is
(a) 1.5 mm
(b) 3 mm
(c) 4.5 mm
(d) 6 mm
data tee
12
13What do you mean by coherent source.12
14The wavefront of a lightbeam is given by the equation ( x+2 y+3 z=c, ) (where ( c )
is arbitary constant) the angle made by the direction of light with the y-axis is:
A ( cdot cos ^{-1} frac{1}{sqrt{14}} )
B. ( cos ^{-1} frac{2}{sqrt{14}} )
c. ( sin ^{-1} frac{1}{sqrt{14}} )
D. ( sin ^{-1} frac{2}{sqrt{14}} )
12
15For which colour is the fringe width minimum?
A . violet
B. red
c. green
D. yellow
12
1670. Calculate the wavelength of light used in an interference
experiment from the following data:
Fringe width = 0.03 cm. Distance between slits and
eyepiece through which the interference pattern is
observed is 1 m. Distance between the images of the
virtual source when a convex lens of focal length 16 cm
is used at a distance of 80 cm from the eyepiece is 0.8 cm
(a) 6000 Å
(b) 0,00006 Å
(c) 6000 cm
(d) 0.00006 m
12
17The angle between polariser and
analyser is ( 30^{circ} ) The ratio of intensity of incident light and transmitted by the analyser is
A. 3: 4
B. 4: 3
c. ( sqrt{3}: 2 )
D. ( 2: sqrt{3} )
12
18For constructive interference, the path difference between two waves must be
A ( cdot(2 n+1) lambda / 2 )
B. ( (2 n+1) lambda )
c. ( _{n frac{lambda}{2}} )
D. ( n lambda )
12
19The tip of a needle does not give a sharp image on a screen. This is due to
A. Polarisation
B. Interference
c. Diffraction
D. None of these
12
20A person wants to see two pillars from a distance of ( 11 mathrm{km}, ) separately. The distance between the pillars must be approximately
A. 3.2m
B. ( 1 mathrm{m} )
c. ( 0.25 mathrm{m} )
D. 0.5 ( m )
12
21In YDSE of equal width slits, if intensity
at the centre of screen is ( I_{0}, ) then
intensity at a distance of ( beta / 4 ) from the
central maxima is ( (beta ) is the fringe
width) :
A ( cdot I_{0} )
в. ( frac{I_{0}}{2} )
c. ( frac{I_{0}}{4} )
D. ( frac{I_{0}}{3} )
12
2212. As the beam enters the medium, it will
(a) diverge
(b) converge
(c) diverge near the axis and converge near the periphery
(d) travel as a cylindrical beam
12
23The interfering fringes formed by a thin oil film on water are seen in yellow light of sodium lamp. We find the fringes
A . coloured
B. black and white
c. yellow and black
D. coloured white yellow
12
24( S_{1}, S_{2} ) are two coherent sources (having
initial phase difference zero) of sound
located along ( x- ) axis separated by ( 4 lambda )
where ( lambda ) is wavelength of sound emitted
by them. Number of maxima located on
the elliptical boundary around it will be :
A . 16
B. 12
( c )
( D .4 )
12
25What will be the wavelength of the ( x ) rays which give a diffraction angle ( 2 theta )
equal to ( 16.80^{circ} ) for a crystal, if the inter planner distance in the crystal is 0.200 nm and only first order diffraction is
observed ( left(sin 8.40^{circ}=0.146right) )
12
When a beam of light of intenisty
( 1 W m^{-2} ) is made an incident normally
on the mirror, it gets displaced so that
the thread makes angle ( theta ) with the
vertical. Assuming the mirror is
perfectly reflecting, the value of ( boldsymbol{theta} )
(Consider it very small) is
( ^{A} cdot frac{2 I m}{c a q} )
в. ( frac{2 I c}{m a} )
c. ( frac{2 I g}{c a m} )
D. ( frac{2 I a}{c m q} )
12
27Unpolarised light is incident from air on
a plane surface of a material of
refractive index’ ( mu^{prime} . ) At a particular
angle of incidence ( ^{prime} boldsymbol{i}^{prime}, ) it is found that the reflected and refracted rays are
perpendicular to each other. Which of the following options is correct for this situation?
A ( cdot i=sin ^{-1}left(frac{1}{mu}right) )
B. Reflected light is polarised with its electric vector parallel to the plane of incidence
C. Reflected light is polarised with its electric vector perpendicular to the plane of incidence
D. ( i=tan ^{-1}left(frac{1}{mu}right) )
12
28The YDSE apparatus is as shown in the
figure. The condition for point ( boldsymbol{P} ) to be a
dark fringe is ( (l= ) wavelength of light
waves)
A ( cdotleft(l_{1}-l_{3}right)+left(l_{2}-l_{4}right)=n lambda )
( left(l_{1}-l_{2}right)+left(l_{3}-l_{4}right)=frac{(2 n+1) lambda}{2} )
c. ( left(l_{1}+l_{3}right)+left(l_{2}+l_{4}right)=frac{(2 n-1) lambda}{2} )
( left(l_{1}-l_{2}right)+left(l_{4}-l_{3}right)=frac{(2 n-1) lambda}{2} )
12
29Assertion
Thin films such as soap bubble or a thin layer of oil on water show beautiful
colors when illuminated by white light.
Reason

It happens due to the interference of light reflected from the upper surface of thin film.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct

12
30Two sound speakers are driven in phase by an audio amplifier at frequency ( 600 H z . ) The speed of sound is ( 340 m / s )
The speakers are on the ( y ) -axis, one at ( boldsymbol{y}=+mathbf{1 . 0 m} ) and the other at ( boldsymbol{y}= )
( -1.0 m . ) A listener begins at ( y=0 ) and
walks along a line parallel to the ( y ) -axis
at a very large distance ( x ) away. How
many maxima can she possibly hear if she keeps walking in the same direction?
12
31Young’s double slit experiment is performed at 589 nm light with a distance of ( 2.00 mathrm{m} ) between the slits
and the screen. The tenth
interference minimum is observed 7.26
( mathrm{mm} ) from the central maximum. The
spacing of the slits is
A. ( 15.4 m m )
B. ( 154 m m )
c. ( 1.54 m m )
D. ( 0.154 mathrm{mm} )
12
3233. A double-slit arrangement produces interference fringes
for sodium light (a = 589 nm) that have an angular
separation of 3.50 x 0-rad. For what wavelength would
the angular separation be 10% greater?
(a) 527 nm
(b) 648 nm
(c) 722 nm
(d) 449 nm
12
33BA
pe
2. Figure shows that P and are two equally intense coherent
of wavelength 20 m. The
separation PQ is 5.0 m and
phase of P is ahead of the
phase of Q by 90°. A, B and
C are three distant points of
observation equidistant from the mid-point of PQ. The
intensity of radiations at A, B, C will bear the ratio
(a) 0:1:4
(b) 4:1:0
(c) 0:1:2
(d) 2:1:0
1.
000 and noth :ffavene
12
34In Young’s double-slit experiment, the
separation between the slits is ( boldsymbol{d} ) distance between the slit and screen is
( D(D>>d) . ) In the interference pattern,
there is a maxima exactly in front of
each slit. Then the possible wavelength(s) used in the experiment
are
A ( cdot d^{2} / D, d^{2} / 2 D, d^{2} / 3 D )
B . ( d^{2} / D, d^{2} / 3 D, d^{2} / 5 D )
C . ( d^{2} / 2 D, d^{2} / 4 D, d^{2} / 6 D )
D. none of these
12
35Unpolarized light of intensity ( 32 W m^{-2} ) passes through three polarizes such that the transmission axis of the last
polarizers is crossed with that of the first. The intensity of final emerging light is ( 3 W m^{-2} ). The intensity of light transmitted by the first polarizered will be
( mathbf{A} cdot 32 W m^{-2} )
B. ( 16 mathrm{Wm}^{-2} )
( mathrm{c} cdot 8 mathrm{Wm}^{-2} )
D. ( 4 mathrm{Wm}^{-2} )
12
36When a low flying aircraft passes over head, we sometimes notice a slight
shaking of the picture on our TV screen Identify the optical phenomenon behind ¡t.
12
37Plane of polarisation is:
This question has multiple correct options
A. the plane in which vibrations of the electric vector takes place
B. a plane perpendicular to the plane in which vibrations of the electric vector takes place
C . perpendicular to the plane of vibration
D. horizontal plane
12
38A water film having a refractive index of 1.33 in air is 320 nm thick. If it is illuminated with white light at normal incidence, the light of what wavelength (in ( mathrm{nm} ) ) will appear to be in reflected light?12
39If ( z=frac{lambda D}{2 d} )
( A )
B. 1/2
( c cdot 3 / 2 )
D. 2
12
40200
49. Out of the following statements which is not correct?
(a) When unpolarised light passes through a Nicol’s
prism, the emergent light is elliptically polarised
(b) Nicol’s prism works on the principle of double
refraction and total internal reflection
(c) Nicol’s prism can be used to produce and analyse
polarised light
(d) Calcite and Quartz are both doubly refracting crystals
12
41A white light is passed through the two
narrow slits and produced a pattern of
alternating bright and dark lines on the
screen as shown above. What will
effects on the central bright band, if the
distance between screen and slits are
increased?
A. become wider
B. become narrower
C. remain unchanged
D. disappear completely
E . rotate ( 90^{circ} )
12
42Draw a neat labelled diagram of reflection of light from a plane reflecting surface on the basis of wave theory.12
4325. In Young’s double-slit experiment, how many
maximas can be obtained on a screen (including the
central maximum) on both sides of the central fringe
(a = 2000 Å)?
(a) 12
(b) 7
(c) 18
(d) 4
12
44White light reflected at normal incidence from a soap film has minima
at ( 6500 A ) and maxima at ( 7500 A ) in the
visible region with not minima in between. If ( mu ) is ( frac{5}{3} ) for the thin film, the thickness of film is :
A ( cdot 7.40 times 10^{-7} mathrm{cm} )
B. ( 9.75 times 10^{-5} mathrm{mm} )
c. ( 9.70 times 10^{-7} mathrm{cm} )
D. ( 9.75 times 10^{-4} mathrm{mm} )
12
45statement 1: In Young’s experiment, the fringe width for dark fingers is different from that for white fringes. statement 2: In Young’s double slit experiment the fringes are performed with a source of white light, then only black and bright fringes are observed.
A. If both statement 1 and statement 2 are true but statement 2 is the correct explanation of statement
B. If both statement 1 and statement 2 are true but statement 2 is not the correct explanation statemen
c. If statement 1 is true but statement 2 is false
D. If both the statement 1 and statement 2 are false
E. If statement 2 is true but statement 1 is false
12
46Figure shows plane waves refracted
from air to water using Huygen’s principle ( a, b, c, d, e ) are lengths on the diagram. Find the ratio of refractive
index of water w.r.t. air.
12
47A beam of light consists of a bundle of light rays.
A . True
B. False
12
48sources of light of wavelength ( lambda ) are placed on the dotted line in front of a large screen. The source emit waves in
phase with each other. The distance
between ( S_{1} ) and ( S_{2} ) is ( ^{prime} d^{prime} ) while their
distance from the screen is much
larger. Then,
(a) If ( d=7 lambda / 2, O ) will be minima
(b) If ( d=4.3 lambda ), there will be total of 8
minima on y-axis
(c) If ( d=7 lambda, O ) will be maxima.
(d) If ( d=lambda ), there will be only one
maxima on the screen.
Which is the set of correct statement:
A. ( a, b ) and ( c )
B. ( b, c ) and ( d )
c. ( a, b, c ) and ( d )
D. ( a, c ) and ( d )
12
49A double slit is illuminated by light of wave length ( 6000 A^{0} ). The slits are ( 0.1 mathrm{cm} )
apart and the screen is placed 1 m away Then the angular position of 10 th maxima is
A . ( 6 times 10^{-3} r a d )
c. ( 0.006^{circ} )
D. ( 6^{circ} )
12
50Can we perform Young’s double slit experiment with sound waves? To get a reasonable “fringe pattern”, what should be the order of separation between the slits? How can the bright fringes and the dark fringes be detected in this case?12
51When two progressive waves of
intensity ( boldsymbol{I}_{1} ) and ( boldsymbol{I}_{2} ) but slightly different
frequencies superpose, the resultant
intensity fluctuates between
( mathbf{A} cdot(sqrt{I_{1}}+sqrt{I_{2}})^{2} ) and ( (sqrt{I_{1}}-sqrt{I_{2}})^{2} )
B ( cdot(sqrt{I_{1}}-sqrt{I_{2}}) ) and ( (sqrt{I_{1}}+sqrt{I_{2}}) )
( mathbf{C} cdotleft(I_{1}+I_{2}right) ) and ( left(I_{1}-I_{2}right) )
D. ( left(I_{1}+I_{2}right)^{2} ) and ( left(I_{1}-I_{2}right)^{2} )
12
52In Young’s double slit experiment the intensity of the maxima is ( I . ) If the width of each slit is doubled, the intensity of
the maxima will be:
( mathbf{A} cdot I / 2 )
B. ( 2 I )
c. ( 4 I )
D. ( I )
12
53A biprism is placed at a distance of 50 ( mathrm{mm} ) in front of a narrow slit illuminated by light of wavelength ( 600 mathrm{nm} ). The virtual images formed by the biprism are ( 0.5 mathrm{mm} ) apart. Find the width of the
fringes formed on a screen placed 0.75 ( mathrm{m} ) apart in front of the biprism.
A. ( 0.96 mathrm{cm} )
B. ( 0.096 mathrm{cm} )
c. ( 0.0096 mathrm{cm} )
D. 9.6 ( mathrm{cm} )
12
54Two loud speakers ( L_{1} ) and ( L_{2}, ) driven by a common oscillator and amplifier, are arranged as shown. The frequency of the oscillator is gradually increased from
zero and the detector at D records a
series of maxima and minima. If the
speed of sound is ( 330 mathrm{m} / mathrm{s} ) then the
frequency at which the first maximum is observed is :
A . ( 165 mathrm{Hz} )
в. ззо нz
c. 495 нz
D. 660 нz
12
5527. In Young’s double-slit experiment, 30 fringes are
obtained in the field of view of the observing telescope,
when the wavelength of light used is 4000 Ă. If we use
monochromatic light of wavelength 6000 X, the number
of fringes obtained in the same field of view is
(a) 30
(b) 45
(d) none of these
(c) 20
muiment the concretion between
12
56In a Young’s double slit experiment D equals the distance of screen and dis
the separation between the slit. The distance of the nearest point to the
central maximum where the intensity is
same as that due to a single slit, is equal to:-
A. ( frac{D lambda}{d} )
в. ( frac{D lambda}{2 d} )
c. ( frac{D lambda}{3 d} )
D. ( frac{2 D lambda}{d} )
12
57In a YDSE, if the incident light consists
of two wavelengths ( lambda_{1} ) and ( lambda_{2} ), the slit separation is ( d ), and the distance
between the slit and the screen is ( D )
the maxima due to each wavelength will coincide at a distance from the central
maxima, given by
A ( frac{lambda_{1}+lambda_{2}}{2 D d} )
в. ( _{text {LCM of }} frac{lambda_{1} D}{d} ) and ( frac{lambda_{2} D}{d} )
c. ( _{left(lambda_{1}+lambda_{2}right)} frac{2 D}{D} )
D. ( _{text {HCF of }} frac{lambda_{1} D}{d} ) and ( frac{lambda_{2} D}{d} )
12
58When two tuning forks ( A ) and ( B ) are
sounded together, 4 beats per second
are heard. The frequency of the fork ( B ) is
( 384 H z . ) When one of the prongs of the
fork ( A ) is filed and sounded with ( B ), then
beat frequency increases, then
frequency of the fork ( boldsymbol{A} ) is
A. ( 380 H z )
в. 388 Нг
c. 379 Н ( z )
D. ( 389 ~ H z )
12
59In Young’s double slit experiment width
sodium vapour lamp of wavelength 589 nm and the slits 0.589 mm apart, the
half angular width of the central maximum is
( A cdot sin ^{-1}(0.01) )
B. ( sin ^{-1}(0.0001) )
( c cdot sin ^{-1}(0.001) )
D. ( sin ^{-1}(0.1) )
12
60In Young’s double slit experiment:
A. only interference occurs
B. only diffraction occurs
c. both interference and diffraction occurs
D. polarisation occurs
12
61Two waves of amplitudes ( A ) and ( 3 A ) are superposed and they have a phase difference of ( pi . ) What kind of
interference is possible
A. constructive interference
B. Destructive interference
c. Interference depends on wavelength difference
D. Interference depends on frequency difference
12
62Polarisation of light was first successfully explained by:
A. corpuscular theory
B. Huygens’ wave theory
c. Electromagnetic wave theory
D. Planck’s theory
12
63Microwaves from a transmitter are
directed normally toward a plane reflector. A detector moves along the normal to the reflector. Between
positions of 14 successive maxima the
detector travels a distance 0.14 m. The
frequency of the transmitter is ( (c= ) ( 3 times 10^{8} m s^{-1} )
A. ( 1.5 times 10^{10} mathrm{Hz} )
в. ( 10^{10} mathrm{Hz} )
c. ( 3 times 10^{10} H z )
D. ( 6 times 10^{10} mathrm{Hz} )
12
6436. In Young’s double-slit experiment, the slit separation is
0.5 mm and the screen is 0.5 m away from the slit. For a
monochromatic light of wavelength 500 nm, the distance
of 3rd maxima from the 2nd minima on the other side of
central maxima is
(a) 2.75 mm
(b) 2.5 mm
(c) 22.5 mm
(d) 2.25 mm
12
65A narrow tube is bent in the form of a
circle of radius ( R, ) as shown in the
figure. Two small holes ( S ) and ( D ) are made in the tube at the positions right
angle to each other. A source placed at
S generated a wave of intensity ( l_{0} ) which is equally divided into two parts : One part travels along the longer path, while the other travels along the shorter path. Both the part waves meet at the point D where a detector is placed. If a maxima is formed at the detector then, the
magnitude of wavelength ( lambda ) of the wave
produced is given by :
This question has multiple correct options
A . ( pi R )
в. ( frac{pi R}{2} )
c. ( frac{pi R}{4} )
D. ( frac{2 pi R}{3} )
12
66Find the fringe width for the pattern
obtained under given arrangement on
the screen.
( ^{A} cdot frac{lambda f}{2 t} )
в. ( frac{lambda f}{t} )
c. ( frac{t f}{lambda} )
D. ( frac{t f}{2 lambda} )
12
67A beam of natural light falls on a
system of 6 Polaroids, which are arranged in succession such that each
of the Polaroid is turned through ( 30^{circ} ) with respect to the proceeding the one. The percentage of incident intensity that passes through the system will be:
( mathbf{A} cdot 100 % )
B. ( 50 % )
( c .30 % )
D. ( 12 % )
12
68What is matter waves? Write any two
characteristics of it.
12
69The wavefront of a light beam is given by the equation ( boldsymbol{x}+mathbf{2} boldsymbol{y}+mathbf{3} boldsymbol{z}=boldsymbol{c} )
(where ( c ) is arbitrary constant) then what is the angle made by the direction of light with the y-axis?
A ( cdot cos ^{-2} frac{2}{sqrt{14}} )
B. ( cos ^{-1} frac{2}{sqrt{14}} )
( mathrm{c} cdot cos ^{-3} frac{2}{sqrt{14}} )
D. ( cos ^{-4} frac{2}{sqrt{14}} )
12
70In Young’s double slits experiment, if the separation between the slits is halved, and the distance between the
slits and the screen is doubled, then the fringe width compared to the original one will be?
A. Unchanged
B. Halved
c. Doubled
E. Fringes will disappear
12
71If monochromatic red light is replaced by green light, then the fringe width:
A . increases
B. remains same
c. can’t say
D. decreases
12
72Pile of plates can be used to produce completely polarised light due to :
A. Reflection
B. Refraction
c. Double refraction
D. A and B
12
73In Young’s double slit experiment wavelength of light is 6000 A The the phase difference between the light waves reaching the third bright fringe from the central fringe will be:
( mathbf{A} cdot mathbf{0} )
в. ( 2 pi )
c. ( 4 pi )
D. ( 6 pi )
12
74Angle of incidence is equal to the angle
of reflection.
A . Always
B. Sometimes
c. Under special condition
D. Never
12
75wavefront and ( A O ) and ( B P ) the
corresponding extreme rays of
monochromatic light of wavelength ‘ ( lambda ).
The value of angle ( theta ) for which the ray ( mathrm{BP} )
and the reflected ray OP interfere
constructively is given by:
A ( cdot cos theta=frac{3 lambda}{4 d} )
B. ( cos theta=frac{lambda}{4 d} )
( mathrm{c} cdot sec theta=frac{lambda}{3 d} )
D ( sec theta=frac{2 lambda}{3 d} )
12
76Visible light passing through a circular hole forms a diffraction disc of radius
( 0.1 mathrm{mm} ) on a screen. If ( mathrm{X} ) -ray is passed through the same set up, the radius of the diffraction disc will be
A . zero
B. 0.1 ( m m )
12
77What is the Brewster angle for air to glass transition? (Refractive index of
glass is 1.5 ).
12
78A single slit Fraunhoffer diffraction pattern is formed with white light. For what wavelength of light the third secondary maximum in the diffraction pattern coincides with the second
secondary maximum in the pattern for red light of wavelength 6500 A?
B . ( 4642 A^{circ} )
c. ( 4100 A^{circ} )
D. ( 4400 A^{circ} )
12
79Wavelength of light used in an optical instrument are ( lambda_{1}=4000 hat{A} ) and ( lambda_{2}= ) ( mathbf{5 0 0 0} boldsymbol{A} ) then ratio of their respective
resolving powers(corresponding to ( lambda_{1} )
and ( lambda_{2} ) ) is
A. 16: 25
B. 9:
( c cdot 4: 5 )
D. 5:
12
80When the sun rays are incident at an
angle of ( 60^{0} ) then intensity is ( I . ) What will be the intensity if the sun rays are
incident at ( 30^{circ} ? )
A ( cdot frac{I}{sqrt{3}} )
B. ( sqrt{3} I )
c. ( 3 I )
D. ( frac{1}{3} )
12
81In double slit experiment, when interference pattern due to whitelight is observed by an observer through a transparent glass of green colour, he finds black and green bright fringes. If green glass is replaced by violet colour glass, then:
A. No interference pattern will appear
B. Bright violet fringes will appear to be of smaller width than green fringes
C. Bright violet fringes will appear to be of more width than green fringes
D. Bright fringes will be produced of the same width as that of green fringes
12
82In YDSE, let ( A ) and ( B ) be two slits. Films
of thicknesses ( t_{A} ) and ( t_{B} ) and refractive
indices ( mu_{A} ) and ( mu_{B} ) are placed in front of
( A ) and ( B, ) respectively. If ( mu_{A} t_{A}=mu_{B} t_{B} )
then the central maxima will :
A. Not shift
B. Shift toward ( A )
c. shift toward ( B )
D. (b) if ( t_{B}>t_{A} ) and (c) if ( t_{B}<t_{A} )
12
83In Young’s double slit experiment, the two slits act as coherent sources of
equal amplitude a and of wavelength ( lambda ) In another experiment with the same set up, the two slits are source of equal
amplitude ( n ) and wavelength ( lambda ), but are incoherent. The ratio of intensities of
light at the mid point of the screen in the first case to that in the second case
is
A .2: 1
B . 1: 2
( c cdot 3: 4 )
( D cdot 4: 3 )
12
84If the whole bi-prism experiment is immersed in water then the fringe width becomes, if the refractive indices
of bi-prism material and water are 1.5 and 1.33 respectively,
A. 3 times
B. ( frac{3}{4} ) times
c. ( frac{4}{3} ) times
D. ( frac{1}{3} ) times
12
85A ( 600 n m ) light is perpendicularly
incident on a soap film suspended in
air. The film is ( 1.00 mu m ) thick with ( n= )
1.35. Which statement most accurately
describes the interference of light reflected by the two surfaces of the film?
A. The waves are close to destructive interference
B. The waves are close to constructive interference
c. The waves show complete destructive interference
D. The waves show complete constructive interference
12
86For a glass plate as a polariser with
refractive index 1.633 , calculate the
angle of incidence at which light is polarised.
12
87A plane wave front falls on a convex lens
The emergent wave front:
A. converges to a point
B. diverges from a point
c. does not suffer any refraction
D. may or may not converge at point
12
8816. In Young’s double slit experiment, one of the slit is wider
than other, so that amplitude of the light from one slit
is double of that from other slit. If I be the maximum
intensity, the resultant intensity I when they interfere at
phase difference o is given by
(a) L (4 + 5 cosø (b) 5 (1+2 cos? )
c) ‘s(1+400) « ‘;{1+8 cm)
(AIEEE 2012)
12
89of intensity ( I ) is incidents on a glass plate as shown, in the figure. Another identical glass plate is kept close to the
first-one and parallel to it. Each glass plate reflects ( 25 % ) of the light incident on it and transmits the remaining. Then
the ratio of the maximum and
minimum intensities in the
interference pattern formed by the two
beams obtained after one reflection at
each plate is
A . 7: 1
B. 49: 1
c. 4: 1
D. 16: 9
12
90An unpolarized beam of light is incident on a group of four polarizing sheets,
which are arranged in such a way that the characteristic direction of each
polarizing sheet makes an angle of ( 30^{circ} )
with that of the preceding sheet. The fraction of incident unpolarized light transmitted is
A ( cdot frac{27}{128} )
B. ( frac{128}{27} )
c. ( frac{37}{128} )
D. ( frac{128}{37} )
12
91What is wavefront? Describe Huygen’s
theory of secondary wavelets.
12
92A polarizer -analyser set is adjusted such that the intensity of light coming out of the analyser is just ( 10 % ) of the original intensity. Assuming that the polarizer-analyser set does not absorb any light, the angle by which the analyser need to be rotated further to
reduce the output intensity to be zero, is:
A . ( 90^{circ} )
в. ( 71.6^{circ} )
c. ( 18.4^{circ} )
D. ( 45^{circ} )
12
93Anti-nodal curves represent the points joining:
A. destructive interference
B. constructive interference
c. equal phase curves
D. equal pressure curves
E. zero pressure curves
12
94A fringe width of a certain interference
pattern is ( beta=0.002 mathrm{cm} . ) What is the
distance of ( 5^{t h} ) dark fringe from centre?
( mathbf{A} cdot 1 times 10^{-2} mathrm{cm} )
B. ( 11 times 10^{-2} mathrm{cm} )
( mathrm{c} cdot 1.1 times 10^{-2} mathrm{cm} )
D. ( 3.28 times 10^{6} mathrm{cm} )
12
952. The transverse nature of light is shown by
(a) interference of light (b) refraction of light
(c) polarisation of light (d) dispersion of light
(AIEEE 2002)
12
96Two light waves of intensities ( ^{prime} I_{1}^{prime} ) and ( ^{prime} I_{2}^{prime} ) having same frequency pass through
same medium at a time in same
direction and interfere. The sum of the
minimum and maximum intensities is
( mathbf{A} cdotleft(I_{1}+I_{2}right) )
B ( cdot 2left(I_{1}+I_{2}right) )
C ( cdotleft(left(sqrt{I}_{1}+sqrt{I}_{2}right)right) )
D. ( left(left(sqrt{I}_{1}-sqrt{I}_{2}right)right) )
12
97In a Young’s double-slit experiment, the fringe width is ( beta . ) If the entire
arrangement is now placed inside a liquid of refractive index ( mu ), the fringe width will become
( mathbf{A} cdot mu beta )
в. ( frac{beta}{mu} )
( c cdot frac{beta}{mu+1} )
D. ( frac{beta}{mu-1} )
12
98A narrow tube is bent in the form of a
circle of radius ( R, ) as shown in the
figure. Two small holes ( S ) and ( D ) are made in the tube at the positions right
angle to each other. A source placed at
S generated a wave of intensity ( l_{0} ) which is equally divided into two parts : One part travels along the longer path, while the other travels along the shorter path. Both the part waves meet at the point ( D ) where a detector is placed. If the minima is formed at the detector then,
the magnitude of wavelength ( lambda ) of the wave produced is given by :
This question has multiple correct options
A. ( 2 pi R )
R
R. ( 2 pi )
в. ( frac{3 pi R}{2} )
c. ( frac{2 pi R}{3} )
D. ( frac{2 pi R}{5} )
12
99State and explain Brewster’s law.12
100Sets of travelling waves are given as shown in above figure Identify which set of waves has already been through interference?
( A cdot A )
B. B
( c cdot c )
D.
E.
12
1014. A plane wavefront traveling in a straight line in vacuum
encounters a medium of refractive index u. At P, the shape
of the wavefront is
u
(a)
12
102In the case of the waves from two
coherent sources ( S_{1} ) and ( S_{2}, ) there will
be constructive interference at an
arbitrary point ( P ), the path difference
( boldsymbol{S}_{1} boldsymbol{P}-boldsymbol{S}_{2} boldsymbol{P} ) is then
A ( cdotleft[n+frac{1}{2}right] lambda )
B. ( n lambda )
c. ( left[n-frac{1}{2}right] lambda )
D. ( frac{lambda}{2} )
12
103In an interference pattern of two waves fringe width is ( beta . ) If the frequency of source is doubled then fringe width will become:-
A ( cdot frac{1}{2} beta )
B. ( beta )
( c cdot 2 beta )
D. ( frac{3}{2} )
12
104A small coin is resting on the bottom of
a beaker filled with a liquid. A ray of
light from the coin travels upto the
surface of the liquid and moves along
its surface (see figure)How fast is the
light travelling in the liquid?
( mathbf{A} cdot 1.2 times 10^{8} mathrm{m} / mathrm{s} )
B . ( 1.8 times 10^{8} mathrm{m} / mathrm{s} )
C ( .2 .4 times 10^{8} mathrm{m} / mathrm{s} )
D. ( 3.0 times 10^{8} mathrm{m} / mathrm{s} )
12
105The ratio of the intensities at minima to
the maxima in the Young’s double slit experiment is ( 9: 25 . ) Find the ratio of the widths of the two slits.
12
106In Young’s double slit expt. the distance between two sources is ( 0.1 mathrm{mm} ). The
distance of the screen from th source is
20 cm. Wavelength of light used is 5460
A. The angular position of the first dark fringe is
A ( cdot 0.08^{circ} )
B. ( 0.16^{circ} )
( c cdot 0.20^{circ} )
D. ( 0.32^{circ} )
12
107In Young’s double slit experiment the distance d between the slits ( S_{1} ) and ( S_{2} )
is ( 1 mathrm{mm} ). What should the width of each
slit be ( operatorname{so~as~to~obtain~} 10^{t h} ) maxima of
the double slit pattern within the central maximum of the single slit
pattern?
A. ( 0.9 mathrm{mm} )
B. 0.8 mm
( c .0 .2 mathrm{mm} )
D. 0.6 mm
12
108In the Young’s double slit experiment, intensities of black and bright fringes
are 1 and 4 respectively, the ratio of amplitudes of sources will be :
A . 1: 1
B. 1: 2
c. 3: 1
D. 1: 4
12
109If the point object is moved away from
mirror normal to screen then
A. fringe width will increase
B. fringe width will decrease
c. fringe width will first increase then decrease
D. Remain unchanged
12
110A beam of light ( A O ) is incidents on a glass slab ( (mu=1.54) ) in a direction as
shown, in the Fig. The reflected ray ( O B )
is passed through a Nicol prism. On rotating the Nicol prism we observe the
A. the intensity is reduced to zero and remains zero
B. the intensity reduces somewhat and rise again
c. there is no change in intensity
D. the intensity is gradually to reduces to zero and then again it increases
12
111The maximum number of possible interference maxima, for slit-separation
equal to twice the wavelength,in Young’s double-slit experiment, is
A . Infinite
B. Five
c. Three
D. zero
12
112A plane wave of wavelength ( 6250 A ) is
incident normally on a slit of width ( 2 x )
( 10^{-2} mathrm{cm} . ) The width of the principal
maximum on a screen distant ( 50 mathrm{cm} )
will be
A. 312.5 ( times 10^{-3} mathrm{cm} )
В. 32.5 ( times 10^{-3} mathrm{m} )
c. ( 312.5 times 10^{-3} mathrm{m} )
D. 312 m
12
113Assume 100 pm ( X ) -ray beam is passed through YDSE. Interference pattern is observed on a photographic plate placed ( 40 mathrm{cm} ) away from the slits. What should be the separation between the slits so that the separation between two successive maxima is ( 0.1 mathrm{mm} )
A ( .4 mu m )
в. ( 0.4 mu m )
( c .4 n m )
D. ( 40 mu m )
12
114In Young’s double slit experiment. the fringe width with light of wavelength ( mathbf{0} )
( 6000 A ) is ( 3 mathrm{mm} ). The fringe width, when the wavelength of light is changed to
( 4000 A ) is
( A cdot 3 m m )
B. ( 1 mathrm{mm} )
( c cdot 2 m m )
D. ( 4 mathrm{mm} )
12
115Three waves are given below.
Sound waves
Il. Visible light waves
III. X-rays
Which of the above waves cannot be
polarised?
A. I only
B. III only
c. I and II only
D. I and III only
E. I, II and III
12
116In YDSE, find the missing wavelength in front of one of the slits.
( ^{A} cdot frac{d^{2}}{2 D} )
B. ( frac{2 d^{2}}{D} )
c. ( frac{d^{2}}{3 D} )
D. ( frac{d^{2}}{4 D} )
12
117In the propagation of polarised light waves, the angle between the plane of vibration and the plane of polarization
is
A ( cdot 0^{circ} )
B. 90
c. 45
D. ( 180^{circ} )
12
118The redistribution of intensity on account of the superposition of two waves is called as:
A. Refraction
B. Polarisation
c. Interference
D. Non of these
12
119In a two-slit experiment, with
monochromatic light, fringes are obtained on a screen placed at some distance from the slits. If the screen is
moved by ( 5 times 10^{-2} mathrm{m} ) towards the slits,
the change in fringe width is ( 10^{-3} mathrm{m} ) The the wavelength of light used is
(given that distance between the slits is
( 0.03 mathrm{mm} )
( A cdot 4500 stackrel{circ}{A} )
B . 5000 ,
c. 5500 ,
D. 6000 ,
12
120Newton’s ring pattern in reflected
system, viewed under white light
consists of
A. Equally spaced bright and dark bands with central dark spot
B. Equally spaced bright and dark bands with central white spot
C. A few coloured rings with central dark spot
D. A few coloured rings with central white spot
12
121According to Huygens, the ether medium pervading entire universe is
A . Less elastic and more dense
B. Highly elastic and less dense
c. Not elastic
D. Much heavier
12
122An isotropic point source emits light. screen is situated at a given distance. If the distance between sources and
screen is decreased by ( 2 % ), illuminance will increase by:
A . ( 1 % )
B. 2%
( c .3 % )
D. ( 4 % )
12
123A mixture of light, consisting of wavelength 590nm and an unknown wavelength, illuminates Young’s double slit and gives rise to two overlapping interference patterns on the screen. The
central maximum of both lights coincide. Further, it is observed that the third bright fringe of known light coincides with the 4 th bright fringe of the unknown light. From this data, the wavelength of the unknown light is
A. ( 885.0 mathrm{nm} )
B. 442.5 nm
c. ( 776.8 mathrm{nm} )
D. 393.4 nm
12
124Choose the correct statement
A. Brewster’s angle is independent of the wavelength of light.
B. Brewster’s angle is independent of nature of reflecting the surface.
C. Brewster’s angle is different for different wavelengths.
D. Brewster’s angle depends on the wavelength but not on the nature of reflecting the surface.
12
125( S_{1} ) and ( S_{2} ) are two coherent sources of
sound having no initial phase
difference. The velocity of sound is 330 ( mathrm{m} / mathrm{s} . ) No maxima will be formed on the
line passing through ( S_{2} ) and
perpendicular to the line joining
( boldsymbol{S}_{1} ) and ( S_{2} . ) If the frequency of both the
sources is :
A. 330 ( mathrm{Hz} )
в. 120 Н ( z )
( c cdot 100 mathrm{Hz} )
D. 220 нz
12
126Huygens’s concept of secondary wave
A. allows us to find the focal length of a thick lens
B. is a geometrical method to a find a wavefront
( mathrm{C} ). is used to determine the velocity of light
D. is used to explain polarisation
12
127A source of light suspended above a circular table at a height equal to the radius of the table gives an intensity at the centre of the table, the intensity at the edge of the table would be (Assuming illuminance remains the same)
A . 0.251
B. 0.5 ।
c. 0.71
D. 2.81
12
128In a Young’s double slit experiment, constructive interference is produced at
a certain point ( P . ) The intensities of
light at ( boldsymbol{P} ) due to the individual sources
are 4 and 9 units. The resultant
intensity at point ( boldsymbol{P} ) will be-
A. 13 units
B. 25 units
c. ( sqrt{97} ) units
D. 5 units
12
129In YDSE distance between slits and
screen is ( 1.5 mathrm{m} ). When light of wavelength 500nm is used then 2nd bright fringe is
obtained on screen at a distance of
10mm from the central bright fringe. What will be the shift in the 2nd bright fringe of the light of wavelength 550nm is used?
( A cdot 2 m m )
B. ( 1 mathrm{mm} )
c. ( 1.5 mathrm{mm} )
D. ( 1.1 mathrm{mm} )
12
130Monochromatic light of wavelength ( mathbf{5 8 9} ) nm is incident from air on a water
surface. What are the wavelength,
frequency and speed of
(a) Reflected, and
(b) Refracted light?
Refractive index of water is 1.33
12
131In the light emerging from calcite
crystal:
A. Both 0 -ray and E-ray are partially polarised
B. Both O-ray and E-ray are completely polarised
C. O-ray is partially polarised and E-ray is completely polarised.
D. O-ray is completely polarised and E-ray is partially polarised.
12
132How many times will he hear a
minimum in sound intensity?
12
133The interference of light was first demonstrated experimentally by
A. sir Isaac Newton
B. Michelson
c. Fraunhoffer
D. Thomas Young
12
134In YDSE The intensity of central bright fringe is ( 8 m W / m^{2} . ) What will be the intensity at ( lambda / 6 ) path difference?
( mathbf{A} cdot 8 m W / m^{2} )
в. ( 6 m W / m^{2} )
( mathbf{c} cdot 4 m W / m^{2} )
( mathbf{D} cdot 2 m W / m^{2} )
12
135Which letter represents the wavelength
of the light in the Young’s double slit
experiment?
( A cdot A )
B. B
( c . c )
D.
( E )
12
136In the case of linearly polarized light, the magnitude of the electric field
vector
A. is parallel to the direction of propagation
B. does not change with time
c. increases linearly with time
D. varies periodically with time
12
137What is the difference between
polarised light and unpolarised light?
12
polarised.

Reason: Sound waves in air are
longitudinal in nature.
A. If both assertion and reason are true but the reason is the correct explanation of assertion
B. If both assertion and reason are true but the reason is not the correct explanation of assertion
c. If assertion is true but reason is false
D. If both the assertion and reason are false
E. If reason is true but assertion is false

12
139Two coherent sources of wavelength ( 6.2 times 10^{-7} mathrm{m} ) produce interference. The
path difference corresponding to ( 10^{t h} ) order maximum will be?
A ( .6 .2 times 10^{-6} mathrm{m} )
В. ( 3.1 times 10^{-6} mathrm{m} )
c. ( 1.5 times 10^{-6} mathrm{m} )
D. ( 12.4 times 10^{-6} mathrm{m} )
12
140Sunlight is reflected from a calm lake. The reflected light is ( 100 % ) polarized at a certain instant. The angle between the sun light and the surface of lake is ( (mu ) of
water is ( frac{4}{3} ) ) ( left(tan ^{-1}left(frac{4}{3}right)=53^{circ} 4^{prime}right) )
A .90
В. ( 53^{circ} 4^{prime} )
( mathbf{c} cdot 36^{circ} 56^{prime} )
D. 45
12
141In studying diffraction pattern of different obstacles, the effect of:
A. full wave front is studied
B. portion of a wave front is studied
c. waves from two coherent sources is studied
D. waves from one of the coherent source is studied
12
142Newton postulated his corpuscular theory of light on the basis of
A. newton’s rings
B. rectilinear propagation of light
c. colour through thin films
D. dispersion of white light into colours
12
143In Fraunhofer diffraction experiment, ( boldsymbol{L} )
is the distance between screen and the
obstacle, ( b ) is the size of obstacle and ( A )
is wavelength of incident light. The general condition for the applicability of Fraunhofer diffraction is
( ^{mathrm{A}} cdot frac{b^{2}}{L lambda} gg 1 )
B. ( frac{b^{2}}{L lambda}=1 )
c. ( frac{b^{2}}{L lambda} ll 1 )
D. ( frac{b^{2}}{L lambda} neq 1 )
12
1444. The maximum number of possible interference maxima
for slit-separation equal to twice the wavelength in
Young’s double-slit experiment is
(a) infinite
(b) five
(c) three
(d) zero (AIEEE 2004)
12
145Resolving power of a telescope
increases with
A. increase in focal length of eye-piece
B. increase in focal length of objective
C. increase in aperture of eye piece
D. increase in aperture of objective
12
146Explain why the intensity of light
coming out of a polaroid does not change irrespective of the orientation of
the pass axis of the polaroid.
12
147Sound signal is sent through a composite tube as shown in figure. The radius of the semicircle is r. Speed of
sound in air is ( V ). The source of sound is
capable to generate frequencies in
the range ( f_{1} ) to ( f_{2}left(f_{2}>fright) . ) If ‘n’ is an
integer then frequency for maximum intensity is given by :
( A cdot frac{n V}{r} )
B. ( frac{n V}{r(pi-2)} )
( mathbf{c} cdot 7 V / r )
D. ( frac{n V}{(r-2) pi} )
12
148In a Fresnel’s bi-prism experiment, the fringe of width 0.05 mm is observed on
a screen at a distance of ( 1.5 m ) from the
source. When a convex lens is placed between the source and the screen, for
two positions of the lens image of interfering sources are produced on the screen. The separation between the two
images being 0.04 and ( 0.01 m m ) respectively. The wavelength of light used is
( mathbf{A} cdot 6.67 n m )
B. ( 0.667 n m )
( c .667 n m )
D. ( 667 A^{circ} )
12
149In Young’s interference experiment, if
the slits are of unequal width, then
A. no fringes will be formed
B. the positions of minimum intensity will not be completely dark
C. bright fringe as displaced from the original central position
D. distance between two consecutive dark fringes will not be equal to the distance between two consecutive right fringes.
12
150In Young’s double slit experiment, the slits are ( 2 mathrm{mm} ) apart are illuminated by
photons of two wavelengths ( boldsymbol{I}_{1}= ) ( 12000 A ) and ( I_{2}=10000 A ) at what
minimum distance from the common
central bright fringe on the screen ( 2 mathrm{m} ) from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other?
( A cdot 8 m m )
B. 6 mm
( c cdot 4 m m )
D. 3 mm
12
151Where ( d ) is width of the strips. Fringe visibility is defined as
( ^{A} cdot frac{I_{m a x}-I_{m i n}}{I_{m a x}+I_{m i n}} )
B. ( frac{I_{max }+I_{min }}{I_{max }-I_{min }} )
c. ( frac{I_{max }-I_{min }}{I_{max }} )
D. ( frac{I_{max }+I_{min }}{I_{max }+I_{min }} )
12
152When petrol drops from a vehicle fall over rain water on road surface, colours are seen because of:
A. dispersion of light
B. interference of light
c. scattering of light
D. absorption of light
12
153Consider the following statements A & B and identify correct choice in the
(A) When light falls on two polaroid sheets having their axes mutually perpendicular, it is completely extinguished.
(B) When polyvinyl alcohol is subjected to a large strain the molecules get
oriented parallel to the direction of
strain and material becomes
double refractive.
A . A & B are correct
B. Both A & B are wrong
C. A correct B wrong
D. A wrong B correct
12
15467. A parallel beam of white light is incident on a thin film of
air of uniform thickness. Wavelengths 7200 Å and 5400 A
are observed to be missing from the spectrum of reflected
light viewed normally. The other wavelength in the visible
region missing in the reflected spectrum is
(a) 6000 Å
(b) 4320 Å
(c) 5500 Å
(d) 6500 Å
12
155Tenth fringe of wavelength ( 4000 A^{circ} )
coincides with ( 8 t h ) fringes of
wavelength ( lambda ). Then ( lambda ) is
( mathbf{A} cdot 50 n m )
B. ( 555 n m )
c. 450 n ( m )
D. none
12
156If two waves are moving in same
medium and meet at the same time
and both are in the same phase. It will
be:
A. Reflection
B. Refraction
C. Diffraction
D. Constructive interference
E. Destructive interference
12
157On reflection from a plane surface, the following two characteristics get changed:
This question has multiple correct options
A. wavelength
B. Frequency
c. velocity
D. Amplitude
12
158In the set up shown, the two slits ( S_{1} ) and
( S_{2} ) are not equidistant from the slit
S. The central fringe at 0 is then
A. always bright
B. always dark
C. either dark or bright depending on the position of
D. neither dark nor bright
12
159In Young’s double slit experiment, the
two slits act as coherent sources of
equal amplitude ( A ) and wavelength ( lambda ). In
another experiment with the same set up the two slits are same of equal amplitude of wavelength ( lambda ) but are
incoherent. The ratio of intensity of light at the mid point of the screen in the first to the second case is?
A . 4: 1
B . 2: 1
( c cdot 1: 1 )
D. 1: 2
12
160When light is incidence on a diffraction
grating, then the zero order maximum will be
A. spectrum of the colours
B. White
c. one of the component colours
D. Absent
12
161The wave theory of light, in its original form, was first postulated by.
A. Isaac Newton
B. Christian Huygens
c. Thomas Young
D. Augustin Jean Fresnel
12
1626. In Young’s double-slit experiment, a monochromatic
source is used. The shape of the interference fringes
formed on the screen is
(a) a parabola (b) a straight line
(c) a circle
(d) a hyperbola
(AIEEE 2005)
12
163A source emits electromagnetic waves of wavelength ( 3 m . ) One beam reaches
the observer directly and other after reflection from a water surface, travelling 1.5 m extra distance and with intensity reduced to ( frac{1}{4} ) as compared to
intensity due to the direct beam alone.
The resultant intensity will be.
A ( cdotleft(frac{1}{4}right) ) fold
B ( cdotleft(frac{3}{4}right) ) fold
c. ( left(frac{5}{4}right) ) fold
D. ( left(frac{9}{4}right) ) fold
12
164In YDSE, having slits of equal width, let
( beta ) be the fringe width and ( I_{0} ) be the
maximum intensity. At a distance ( x ) from the central bright fringe, the intensity will be
( ^{mathbf{A}} cdot_{I_{0}} cos left(frac{x}{beta}right) )
B. ( _{I_{0} cos ^{2}} frac{2 pi x}{beta} )
c. ( _{I_{0} cos ^{2}} frac{pi x}{beta} )
D. ( frac{I_{0}}{4} cos ^{2} frac{pi x}{beta} )
12
165To measure the-roughness of the surface of a material, which of the following microscope is preferred for better result output?
A. Compound microscope
B. Electron microscope
c. Atomic force microscope
D. None of the above
12
166In Young’s double slit eperiment two disturbances arriving at a point P have phase difference of ( frac{pi}{3} . ) The intensity of this point expressed as a fraction of
maximum intensity ( I_{0} ) is then
A ( cdot frac{3}{2} I_{0} )
в. ( frac{1}{2} I_{0} )
c. ( frac{4}{3} I_{0} )
D. ( frac{3}{4} I_{0} )
12
167The minimum non-zero distance on
screen from central maxima where both
the wave are going to produce maxima
together
A . ( 2000 mu ) m
в. ( 3600 mu ) и
c. ( 4320 mu ) m
D. ( 2160 mu mathrm{m} )
12
168A plane polarized light passed through successive polarizers which are rotated
by ( 30^{circ} ) with respect to each other in the
clockwise direction. Neglecting absorption by the polarizers and given that the first polarizer’s axis is parallel to the plane of polarization of the incident light, the intensity of light at the exit of the fifth polarizer is closest
to.
A. Same as that of the incident light
B. 17.5% of the incident light
c. ( 30 % ) of the incident light
D. zero
12
169Estimate the distance for which ray
optics is good approximation for an aperture of 4 mm and wavelength
( 400 n m )
12
170The condition for destructive
interference is phase difference should
be equal to
A. odd integral multiple of ( pi )
B. Integral multiple of ( pi )
c. odd integral multiple of half ( pi )
D. Integral multiple of half ( pi )
12
171The separation between two coherent
point sources is ( 3 lambda . ) On a line
perpendicular to ( S_{1} S_{2} ) and passing
through ( S_{2} ). Find the smallest distance
where minimum of intensity occurs:
A ( cdot frac{11 lambda}{20} )
B. ( frac{lambda}{2} )
c. ( frac{9 lambda}{20} )
D. ( frac{35 lambda}{4} )
12
172The intensity at the maximum in a
Young’s double slit experiment is ( boldsymbol{I}_{mathbf{0}} )
Distance between two slits is ( d=5 lambda )
,where ( lambda ) is the wavelength of light used in the experiment. What will be the intensity in front of one the slits on the
screen place at a distance ( mathrm{D}=2 mathrm{m} )
12
173Identify which of the following best describe diffraction. Diffraction occurs
when they:
A. travel around an object or through an opening.
B. transition from one medium to another
c. bounce off the surface of an object
D. resonate with the molecules in a medium.
E. pass through a medium unchanged
12
174The intensity of the light coming from
one of the sites in a Young’s double slit
experiment in the intensity from the
other slit. Determine the ratio of the
maximum intensity to the minimum intensity in the interference fringe
pattern observed.
12
175The phenomena which is not explained by Huygen’s construction of the
wavefront
A. reflection
B. diffraction
c. refraction
D. origin of spectrata
12
176State Huygens’ principle.12
177Assertion
Two point coherent sources of light ( boldsymbol{S}_{1} )
and ( S_{2} ) are placed on a line as shown in
figure. ( P ) and ( Q ) are two points on that
line. If at point ( boldsymbol{P} ) maximum intensity is observed, then maximum intensity should also be observed at ( Q )
Reason
In the figure, the distance ( left|boldsymbol{S}_{1} boldsymbol{P}-boldsymbol{S}_{2} boldsymbol{P}right| )
is equal to distance ( left|boldsymbol{S}_{1} boldsymbol{Q}-boldsymbol{S}_{2} boldsymbol{Q}right| )
[
]
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
178What is the path difference of destructive interference:
A ( . n lambda )
B. ( n(lambda+1) )
c. ( frac{(n+1) lambda}{2} )
D. ( frac{(2 n+1) lambda}{2} )
12
179The wavefront of a light beam is given
by the equation ( x+2 y+3 z=c ) (where
( c ) is arbitrary constant of light). What is the angle made by the light with the ( y- ) axis is
( ^{A} cdot cos ^{-1} frac{1}{sqrt{14}} )
B. ( sin ^{-1} frac{2}{sqrt{14}} )
( ^{mathrm{c}} cdot cos ^{-1} frac{2}{sqrt{14}} )
D. ( sin ^{-1} frac{3}{sqrt{14}} )
12
180In a single slit diffraction pattern,
( (a) )
the intensity ( I, ) at a point where the total phase difference between the
wavelets from top to bottom of the slit is
(b) If this point is ( 7^{0} ) away from the central maxima. Find the width of
the slit. Given: ( lambda=600 n m )
12
181Assertion (A): Corpuscular theory fails in explaining the velocity of light in air
to water.

Reason (R) : According to corpuscular theory, light should travel faster in denser media than in rarer media.
A. A and R are true R is correct explanation for A
B. A and R are true R is not correct explanation for A
c. A is true but R is false
D. A is false but R is true

12
182(a) In Young’s double slit experiment, derive the condition for
(i) constructive interference and
(ii) destructive interference at a point
on the screen.
(b) ( A ) bream of light consisting of two
wavelengths, ( 800 n m ) and ( 600 n m ) is
used to obtain the interference fringes in a Young’s double slit experiment on a screen placed ( 1.4 m ) away. If the two
slits are separated by ( 0.28 n m ) calculate the least distance from the
central bright maximum where the bright fringes of the two wavelengths coincide.
12
183Angular width of central maxima of a diffraction pattern of a single slit does not depend upon
A. Distance between slit and source
B. Wavelength of the light used
c. width of slitt
D. Frequency of light used
12
at a frequency of 120 MHz has two
phase. Antenna ( B ) is ( 9 m ) to the right of
antenna ( A . ) Consider point ( P ) at ( a )
horizontal distance ( x ) to the right of
antenna ( A ) as shown figure. The value of
( x ) and order for which the constructive
interference will occur at point ( boldsymbol{P} ) are
This question has multiple correct options
( mathbf{A} cdot x=14.95 m, n=1 )
B ( . x=5.6 m, n=2 )
( mathbf{c} cdot x=1.65 m, n=3 )
D. ( x=0, n=3.6 )
12
185Calculate the number of fringes.
A . 10
B. 20
( c .30 )
D. 40
12
186Monochromatic light of wavelength ( 4500 A ) falls on slit of width ( ^{prime} a^{prime} . ln )
diffraction pattern second maxima
deviates through ( 30 . ) The slit width is
12
187Assertion
Two coherent point sources of light having non-zero phase difference are separated by a small distance. Then, on the perpendicular bisector of line segment joining both the point sources,
constructive interference cannot be
obtained.
Reason
For two waves from coherent point sources to interfere constructively at a
point, the magnitude of their phase
difference at that point must be ( 2 m pi )
(where ( m ) is a non-negative integer)
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct
12
188The phases of the light wave at ( c, d, e )
and ( f ) are ( phi_{c}, phi_{d}, phi_{e} ) and ( phi_{f} ) respectively.
It is given that ( phi_{c} neq phi_{r} )
( mathbf{A} cdot phi_{c} ) cannot be equal to ( phi_{d} )
B. ( phi_{d} ) cannot equal to ( phi_{mathrm{e}} )
( mathbf{c} cdotleft(phi_{d}-phi_{f}right) ) is equal to ( left(phi_{c}-phi_{e}right) )
( mathbf{D} cdotleft(phi_{d}-phi_{c}right) ) is not equal to ( left(phi_{f}-phi_{e}right) )
12
189When waves of same intensity from two coherent sources reach a point with
zero path different the resulting intensity is ( mathrm{K} ). When the above path difference is ( lambda / 4 ) the intensity becomes
( A cdot K )
B. K/2
( c cdot k / 4 )
D. K/8
12
190Which of the following phenomena support the wave theory of light?
(a) Scattering
(b) Interference
( (c) )
Diffraction
Velocity of light in a denser medium is less
(d) than the velocity of light in the rarer medium.
( A cdot A, B, C )
B. A, B, D
( c cdot B, C, D )
D. ( A, C, )
12
191A calcite crystal is placed over a dot on
a piece of paper and rotated. On seeing through the calcite, one will see :
A. one dot
B. Two stationary dots
c. Two rotating dots
D. One dot rotating about the other
12
192A primary monochromatic coherent
source is used in ( Y D S E ) and half of the
space between the primary source and the slits is filled with a transparent
liquid of refractive index ( mu ) with respect
to air, such that path of the wave ( S S_{2} ) is
through this liquid. Everywhere else there is air and slits are sealed with equal glass plates. Find the ocation of central maximum.
12
193When an unpolarized light of intensity
( I_{0} ) is incident on a polarizing sheet, the intensity of the light which does not get transmitted is:
A ( cdot frac{1}{2} I_{0} )
в. ( frac{1}{4} I_{0} )
c. zero
D. ( I_{0} )
12
194Find the angular fringe width in Young’s double slits experiments with a bluegreen light of wavelength 6000 A. The separation between the slits is ( 3.0 x )
( 10^{-3} m )
12
195In young’s experiment, the source of red light of wavelength ( 7 times 10^{-7} ) m. When a
thin glass plate of refractive index 1.5 at this wavelength is put in the path of one of the interfering beams, the central fringe shifts by ( 10^{-3} m ) to the position previously occupied by the 5 th bright fringe. If the thickness of the plate is ( boldsymbol{X} boldsymbol{mu} boldsymbol{m} )
Find ( X ? )
12
19641. What will be the angle of diffracting for the first minimum
due to Fraunhofer diffraction with sources of light of wave
length 550 nm and slit of width 0.55 mm?
12
197Polarisation of light establishes
A. corpuscular theory of light
B. quantum nature of light
c. transverse nature of light
D. all of the above
12
198A source emitting wavelengths ( 480 mathrm{nm} ) and ( 600 mathrm{nm} ) is used in YDSE. The
separation between the slits is 0.25 mm. The interference is observed ( 1.5 mathrm{m} ) away from the slits. The linear separation between first maxima of the
two wavelengths is :
A. ( 0.72 mathrm{mm} )
в. 0.72 ст
c. ( 7.2 mathrm{cm} )
D. ( 7.2 mathrm{mm} )
12
199Sets of travelling waves are given as shown in above figure. Identify which of
the following set of the wave will soon
show destructive interference?
( A cdot A )
B. B
( c cdot c )
D.
E.
12
200White light is normally incidents on a soap film. The thickness of the film is ( 0.5 mu m ) and its refractive index is 1.33 Which wave length will be reflected maximum in the visible region?
A ( .26600 A^{circ} )
B . ( 8860 A^{circ} )
( mathrm{c} .5320 A^{circ} )
D. ( 3800 A^{circ} )
12
201In a plane transmission grating, the width of a ruling is ( 12000 A ) and the width of a slit is ( 8000 A ), the grating element is:
A. ( 20 mu m )
В. ( 2 mu m )
c. ( 200 mu m )
D. ( 10 mu m )
12
202In the Fresnel bi-prism experiment, the refractive index for the bi-prism is ( mu= )
( 3 / 2 ) and fringe width obtained is
( 0.4 m m . ) If the whole apparatus is immersed as such in water then the
fringe width will become(refractive
index of water is ( 4 / 3 ) ).
( mathbf{A} cdot 0.3 m m )
B. ( 0.225 mathrm{mm} )
( c .0 .4 m m )
D. ( 1.2 m m )
12
plane-polarised beams A and B whose planes of vibration are mutually perpendicular. In one position of the analyser, beam B shows zero intensity.
From this position, a rotation of ( 30^{circ} )
shows the two beams as matched in
intensity. The intensity ratio I_(A ( } / I_{-}{B} ) of the two beams is
A ( cdot sqrt{3} )
B. ( 1 / 3 )
c. ( 1 / sqrt{2} )
12
204If ( I_{0} ) is the intensity of the principal maximum in the single slit diffraction pattern, then what will be its intensity
when the slit width is doubled
A. ( I_{0} )
B. ( frac{I_{0}}{2} )
( c cdot 2 I_{0} )
D. ( 4 I_{0} )
12
205To observe diffraction, the size of the
obstacle
A. should be ( lambda / 2 ), where ( lambda ) is the wavelength.
B. should be of the order of wavelength.
C. has no relation to wavelength.
D. should be much larger than the wavelength.
12
206Derive the formula ( omega=frac{D lambda}{2} ) for fringe width in Young’s double slit experiment
The symbols used have their usual meanings.
12
207An analyser is inclined to a polarizer at
an angle of ( 30^{circ} . ) the intensity of light emerging from the analyser is ( frac{1}{n} ) of that is incident on the polarizer. Then ( n ) is equal to
A .4
B. ( frac{4}{3} )
( c cdot frac{8}{3} )
D. ( frac{1}{4} )
12
208A
1. A wave front AB passing
through a system C emerges
as DE. The system C could be
(a) a slit (b) a biprism
(c) a prism (d) a glass slab
B
12
209Phase difference ( (phi) ) and path
difference ( (delta) ) are related by :
A ( cdot frac{2 pi}{lambda} delta )
в. ( frac{pi}{2 lambda} delta )
( c cdot frac{lambda}{2 pi} delta )
D. ( frac{2 lambda}{pi} )
12
210The wavefront is a surface in which
A. all points are in the same phase
B. there is a pair of points in opposite phase
C cdot there is a pair of points with phase difference ( left(frac{pi}{2}right) )
D. there is no relation between the phases
12
211Who amongst the following used corpuscular theory to explain the nature of light?
A. Max Planck
B. Newton
c. Young
D. Einstein
12
212Match the following:
PART-A

PART-B
a)
e) All types of waves Polarisation
( b )
interference
f) longitudinal waves
( c )
diffraction
g) transverse waves
d) reflection
h) only with transverse waves
i) stationary waves produced in stretched strings
( mathbf{A} cdot mathbf{a} rightarrow g ; mathbf{b} rightarrow mathbf{e}, mathbf{f}, mathbf{g}, mathbf{i} ; mathbf{c} rightarrow mathbf{e}, mathbf{f}, mathbf{g} ; mathbf{d} rightarrow mathbf{e}, mathbf{f}, mathbf{g} )
( mathbf{B} cdot mathbf{a} rightarrow mathbf{h}, mathbf{g} ; mathbf{b} rightarrow mathbf{f}, mathbf{g} ; mathbf{c} rightarrow mathbf{g} ; mathbf{d} rightarrow mathbf{h} )
( mathbf{C} cdot mathbf{a} rightarrow mathbf{e}, mathbf{f}, mathbf{g} ; mathbf{b} rightarrow mathbf{g} ; mathbf{c} rightarrow mathbf{e}, mathbf{f}, mathbf{g} ; mathbf{d} rightarrow mathbf{g} )
( mathbf{D} cdot mathbf{a} rightarrow mathbf{e} ; mathbf{b} rightarrow mathbf{h}, mathbf{i} ; mathbf{c} rightarrow mathbf{g}, mathbf{h} ; mathbf{d} rightarrow mathbf{e} )

12
213Polaroid glass is used in sun glasses
because
A. It reduces the light intensity to half on account of polarisation
B. It is fashionable
c. It has good colour
D. It is cheaper
12
214fa maxima is formed at a detector
then the magnitude of wavelength ( lambda ) of the wave produced is given by
A . ( pi R )
в. ( frac{pi R}{2} )
с. ( frac{pi R}{4} )
D. all of these
12
215What is the difference between
polarised light and unpolarished light based on the direction of electric vector
( (vec{E}) ? )
12
216White light reflected from a soap film(Refractive Index=1.5) has a
maxima at 600 nm and a minima at 450
nm with no minimum in between. Then
the thickness of the film is
( times 10^{-7} mathrm{m} )
A . 1
B. 2
( c cdot 3 )
D. 4
12
217If in a birefracting crystal the magnitude
( E_{x} ) and ( E_{y} ) are equal and phase angle
between the two is ( 60^{0} ) then the waves are
A. linearly polarised
B. plane polarised
C. circularly polarised
D. elliptically polarised
12
218When exposed to sunlight, thin films of oil on water often exhibit brilliant
colours due to the phenomenon of
A. the dispersion
B. the interference
c. the diffraction
D. the angular acceleration
12
219A Plane polarized light is incidents on an analyzer. The intensity then becomes three-fourth. The angle of the axis of the analyzer with the beam is
A ( cdot 30^{circ} )
B ( .45^{circ} )
( c cdot 60^{circ} )
D. zero
12
220An unpolarized light beam is incident
on a surface at an angle of incidence
equal to Brewsters angle. Then,
A. the reflected and the refracted beam are both partially polarized
B. the reflected beam is partially polarized and the refracted beam is completely polarized and are at right angles to each other
C. the reflected beam is completely polarized and the refracted beam is partially polarized and are at right angles to each other
D. both the reflected and the refracted beams are completely polarized and are at right angles to each other.
12
221Dichorism means
A. selective absorption of unpolarised light.
B. selective absorption of dispersed light.
C . selective absorption of scattered light.
D. selective absorption of one of the polarised component.
12
222A travelling acoustic wave of frequency ( 500 mathrm{Hz} ) is moving along the positive ( x )
direction with a velocity of ( 300 m s^{-1} )
The phase difference between two
points ( x_{1} ) and ( x_{2} ) is ( 60^{circ} . ) Then the minimum separation between the two pints is
( mathbf{A} cdot 1 mathrm{mm} )
B. ( 1 mathrm{cm} )
c. ( 10 mathrm{cm} )
D. ( 1 mathrm{m} )
12
radius of the semicircle is ( r . ) The speed
of sound in air is ( v ). The source of sound
is capable of generating frequencies in
the range ( f_{1} ) to ( f_{2}left(f_{2}>f_{1}right) . ) If ( n ) is an
integer, frequency for maximum intensity is given by :
A ( cdot frac{n v}{r} )
B. ( frac{n v}{r(pi-2)} )
c. ( frac{n v}{pi r} )
D. ( frac{n v}{(r-2) pi} )
12
224Consider the optical system shown in the figure that follows. The point source
of light ( S ) is having wavelength equal to
lambda. The light is reaching screen only after
reflection. For point ( boldsymbol{P} ) to be ( 2^{n d} ) maxima
the value of ( lambda ) would be ( (D>>d ) and
( boldsymbol{d}>>boldsymbol{lambda}) )
A ( cdot frac{12 d^{2}}{D} )
B. ( frac{6 d^{2}}{D} )
c. ( frac{3 d^{2}}{D} )
D. ( frac{24 d^{2}}{n} )
12
2256. In Young’s double-slit experiment, a monochromatic
source is used. The shape of the interference fringes
formed on the screen is
(a) a parabola (b) a straight line
(c) a circle
(d) a hyperbola
(AIEEE 2005)
12
226If the first minima in Young’s double-slit experiment occurs directly in front of the slits (distance between slit and
( operatorname{screen} D=12 c m ) and distance
between slits ( d=5 c m ) ), then the
wavelength of the radiation used can be
( A cdot 2 c m )
в. 4 ст
c. ( _{overline{3}^{c m}} )
( stackrel{-4}{3}^{c m} )
12
227What happens to the fringe pattern, if in the path of one of the slits a glass plate which adsorbs ( 50 % ) energy is interposed?
A. brightness of fringes will decrease but the dark fringe will become brighter
B. No fringes are observedd
c. The frings width decrease
D. None of the above
12
228Two sound waves travel out from a
common point have frequencies ( 30 mathrm{Hz} ) and ( 40 mathrm{Hz} ) respectively. Calculate the
phase difference between them after
0.8 second?
A. zero
B.
( c cdot frac{5 Pi}{2} )
D. 5Pi
12
229composite tube as shown in the Figure
14.24. The radius of the semicircular
portion of the tube is ( r . ) The speed of
sound in air is ( v . ) The source of sound is
capable of giving sound of varied
frequency. If ( n ) is an integer then frequency for maximum intensity is given by:
( mathbf{A} cdot n v / r )
в. ( n v / r(pi-2) )
c. ( n v / pi r r )
D. ( n v / pi(r-2) )
12
230Young’s double slit experiment is carried out by using green, red and blue light, one color at a time. The fringe
widths recorded are ( beta_{G}, beta_{R}, beta_{B} ) respectively. Then
( mathbf{A} cdot beta_{G}>beta_{B}>beta_{R} )
в. ( beta_{B}>beta_{G}>beta_{R} )
c. ( beta_{R}>beta_{B}>beta_{G} )
D. ( beta_{R}>beta_{G}>beta_{B} )
12
231The class of diffraction in which
incident and diffracted wave fronts are
planar is called:
A. Fresnel diffraction
B. Fraunhofer diffraction
c. Huygens’ diffraction
D. Newton’s diffraction
12
232The parameter which does not change during polarisation of light is?
A. Intensity of light wave
B. Frequency of light wave
c. wavelength of light wave
D. Phase
12
233Find the fringe width of the fringe
pattern
A . ( 0.05 mathrm{cm} )
B. ( 0.25 mathrm{cm} )
( c .0 .01 c m )
D. ( 0.1 mathrm{cm} )
12
234Who proposed wave nature of light?
A. Huygen
B. Youngg
c. Fresnel
D. Maxwell
12
235A beam of light of wavelength 600 nm from a distant source falls on a single
slit ( 1.00 m m ) wide and the resulting
diffraction pattern is observed on a
screen 2 m away. The distance between
the first dark fringe on either side of the central maxima is :
A ( .1 .2 mathrm{cm} )
B. ( 1.2 mathrm{mm} )
( c .2 .4 m m )
D. ( 4.8 mathrm{mm} )
12
236You have learnt in the text how Huygens principle leads to the laws of reflection and refraction. Use the same principle to deduce directly that a point object placed in front of a plane mirror produces a virtual image whose distance from the mirror is equal to the object distance from the mirror.12
23722. In Young’s double-slit experiment, the two slits a
coherent sources of equal amplitude A and of waveleno
2. In another experiment with the same setup, the two slits
are sources of equal amplitude A and wavelength 2, but are
incoherent. The ratio of intensity of light at the mid-point
of the screen in the first case to that in the second case is
(a) 1:1
(b) 1:2
(c) 2:1
(d) 4:1
12
238A certain region of a soap bubble reflects red light of vacuum wavelength ( lambda=650 n m . ) What is the minimum
thickness that this region of the soap bubble could have? Take the index of
reflection of the soap film to be 1.41
A. ( 1.2 times 10^{-7} mathrm{m} )
B. ( 650 times 10^{-9} mathrm{m} )
c. ( 120 times 10^{7} m )
D. ( 650 times 10^{5} mathrm{m} )
12
23962. A light ray of frequency vand wavelength 2 enters a liquid
of refractive index 3/2. The ray travels in the liquid with
(a) frequency v and wavelength
2
(b) frequency v and wavelength
(c) frequency v and wavelength 2.
(d) frequency (3) vand wavelength 2.
1
12
240When unpolarised light is incident on a plane glass plate at Brewster’s angle, then which of the following statements
is correct?
A. Reflected and refracted rays are completely polarised with their planes of polarisation parallel to each other
B. Reflected and refracted rays are completely polarised with their planes of polarisation perpendicular to each other
c. Reflected light is plane polarised but transmitted light is partially polarised
D. Reflected light is partially polarised but refracted light is plane polarised
12
241A student is studying a book placed at the edge of a circular table of radius ( R )
A point source of light is suspended
directly above the centre of the table.
What should be the height of the lamp
so that maximum illuminance is
produced at the position of the book?
A. ( R )
в. ( frac{R}{2} )
c. ( frac{R}{sqrt{2}} )
D. ( frac{R}{sqrt{3}} )
12
242Are ( R_{1}, R_{2}, R_{3}, R_{4} ) and ( R_{5} ) nearly in
phase
A . yes
B. na
( c . ) maintain a constant phase
12
243Ordinary light passes through two polarizing filters. The filters have been rotated so that their polarizing axes are
oriented at ( 90^{circ} ) to each other, and no
light gets through both of them. By adding a third polarizing filter so that there are three in a row, how might
one cause light to pass through the three filters?
A. Orient the third filter so that its polarizing axis is
in front of the first
B. Orient the third filter so that its polarizing axis is rotated ( 45^{circ} ) counter-clockwise relative to the seconds and place it in back of the second
C. Orient the third filter so that its polarizing axis is rotated ( 45^{circ} ) clockwise relative to the first and place it in between the two filters
D. Orient the third filter so that its polarizing axis is rotated ( 90^{circ} ) clockwise relative to the first and place it in front of the first
E. Both A and B will work to allow light through
12
244Which one of the following property of light does not support wave theory of light
A. Light obeys laws of reflection and refraction
B. Light waves get polarised
c. Light shows photoelectric effect
D. Light shows interference
12
245Acceleration of 3 rd maxima w.r.t 3 rd
maxima on other side of central
maxima at ( t=3 s ) is
A ( cdot 0.02 m s^{-2} hat{i} )
B. ( 0.03 m s^{-2} hat{i} )
( mathbf{c} cdot 10 m s^{-2 hat{i}} )
D. ( 0.6 m s^{-2} hat{i} )
12
246Assertion: Thin films such a soap
bubble or a thin layer of oil on water show beautiful colours when
illuminated by white light. Reason: It happens due to the interference of light reflected from the upper surface of the thin film.
A. If both assertion and reason are true but the reason is the correct explanation of assertion
B. If both assertion and reason are true but the reason is not the correct explanation ofassertion
c. If assertion is true but reason is false
D. If both the assertion and reason are false
E. If reason is true but assertion is false
12
247In an experiment of single slit diffraction pattern, first minimum for red light coincides with first maximum
of some other wavelength. If wavelength
of red light is ( 6000 A^{circ} ), then wavelength
of first maximum will be
A ( .3000 A^{circ} )
B . ( 4000 A^{circ} )
c. ( 5000 A^{circ} )
D. ( 6000 A^{circ} )
12
248Which of the following phenomena can be demonstrated by light. But not with sound waves in an air column?
A . Reflection
B. Diffraction
c. Refraction
D. Polarization
12
249The ratio of maximum and minimum intensities in an interference pattern is
( 36: 1 . ) The ratio of the amplitudes of the two interfering waves will be
A . 5: 7
B. 7:4
( c cdot 4: 7 )
D. 7:5
12
250ILLUSTRATION 27.4 Monochromatic light of wavelength
5000 Å is used in YDSE, with slit width, d = 1 mm, distance
between screen and slits, D = 1 m. If intensites at the two slits
are I= 410 and 12 = 1o, find:
(a) fringe width B;
(b) distance of 5th minima from the central maxima on the
screen;
(c) intensity at y = 7 mm;
(d) distance of the 1000th maxima; and
(e) distance of the 5000th maxima.
12
251In diffraction pattern:
A. The fringe widths are equal
B. The fringe widths are not equal
C. The fringes can not be produced
D. The fringe width may or may not be equal
12
252With reference to polarization angle,
( boldsymbol{i}_{boldsymbol{p}}+boldsymbol{r}= )
12
253(a) What is linearly polarized light. Describe briefly using a diagram how sunlight is polarised.
(b) Unpolarised light is incident on a Polaroid. How would the intensity of transmitted light change when the Polaroid is rotated?
12
254(a) (i)’Two independent monochromatic sources of light cannot produce a sustained interference pattern’. Give
reason
(ii) Light wave each of amplitude “a” and frequency ” ( omega ” ), emanating from two coherent light sources superpose at a point. If the displacements due to these
waves is given by ( y_{1}=a c o s omega t ) and
( boldsymbol{y}_{2}=boldsymbol{a} cos (boldsymbol{omega} boldsymbol{t}+boldsymbol{phi}) ) where ( boldsymbol{phi} ) is the phase
difference between the two, obtain the
expression for the resultant intensity at
the point.
(b) In Young’s double slit experiment, using monochromatic light of wavelength ( lambda ), the intensity of light at a point on the screen where path
difference is ( lambda ), is Kunits. Find out the
intensity of light at a point where path difference is ( lambda / 3 )
12
255In Youngs double slit experiment, the fringes are displaced by a distance ( x )
when a glass plate of one refractive index 1.5 is introduced in the path of one of the beams. When this plate in replaced by another plate of the same thickness, the shift of fringes is ( (3 / 2) x ) The refractive index of the second plate
is
A . 1.75
в. 1.50
c. 1.25
D. 1.00
12
256Soap bubble looks coloured due to
A. dispersion
B. reflection
c. interference
D. None of these
12
257According to the principle of complementarity, phenomena can have contradictory properties. These properties cannot be explained simultaneously. Identify phenomenon that are examples of complementarity.
A. Mass and weight
B. Heat and temperature
c. Light waves and particles
D. Magnetic and electric fields
E. Frequency and intensity of sound
12
258Write down four differences between
interference and diffraction:
12
259In Young’s double slit experiment, if monochromatic light used is replaced by white light then :
A. no fringes are observed
B. only central fringe is white, all other fringes are coloured
c. all bright fringes become white.
D. all bright fringes have colour between violet and red
12
260The diffraction effect can be observed in
A. only sound waves
B. only light waves
C. only ultrasonic waves
D. sound as well as light waves
12
2619. In a single slit diffraction experiment first minimum for
red light (660 nm) coincides with first maximum of some
other wavelength 2. The value of l’is
(a) 4400 Å
(b) 6600 Å
(c) 2000 Å
(d) 3500 Å
12
262What is thickness of the plate?
( A .5 mu m )
В. ( 0.005 mu m )
( mathrm{c} .7 mu mathrm{m} )
D. ( 0.007 mu m )
12
263The amplitudes of two interfering waves are ( 4 mathrm{cm} ) and ( 3 mathrm{cm} ) respectively. If the
resultant amplitude is ( 1 mathrm{cm} ) then the
interference becomes
A. constructive
B. Destructive
c. Both constructive and destructive
D. given data is insufficient
12
264In a Young’s Double Slit experiment,
films of thickness ( t_{A} ) and ( t_{B} ) and
refractive indices ( mu_{A} ) and ( mu_{B} ) are placed in front of slits ( A ) and ( B ) respectively. If
( boldsymbol{mu}_{A} boldsymbol{t}_{A}=boldsymbol{mu}_{B} boldsymbol{t}_{B}, ) then the central maxima
( operatorname{may} )
This question has multiple correct options
A. not shift
B. shift forwards A
c. shift towards B
D. None of these
12
265Both light and sound waves produce
diffraction. It is more difficult to observe
the diffraction with light waves
because:
A. light wave do not require medium
B. wavelength of light waves is far smaller
c. light waves are transverse
D. speed of light is far greater
12
2669. Two beams of light having intensities I and 41 interfere to
produce a fringe pattern on a screen. The phase between
the beams is tu2 at point A and n at point B. Then, the
difference between the resultant intensities at A and B is
(a) 21
(b) 41
(c) 51
(d) 71
12
267toppr
microscope is the product of the lateral
magnification ( m_{1} ) of the objective and
the angular magnification ( M_{2} ) of the eyepiece. The former is given by ( boldsymbol{m}_{1}=frac{boldsymbol{S}_{1}^{prime}}{boldsymbol{S}_{1}} )
Where ( S_{1} ) and ( S_{1}^{prime} ) are the object and image distance for the objective lens. Ordinarily the object is very close to the focus, resulting in an image whose distance from the objective is much
larger than the focal length ( f_{1} ). Thus ( S_{1} )
is approximately equal to ( f_{1} ) and ( m_{1}= ) ( -frac{S_{1}^{prime}}{boldsymbol{f}_{1}}, ) approximately. The angular magnification of the eyepiece from ( M=-frac{u^{prime}}{u}=frac{y / f}{y / 25}=frac{25}{f} )
centimeters) is ( M_{2}=25 mathrm{cm} / mathrm{f}_{2}, ) Where
( f_{2} ) is the focal length of the eyepiece, considered as a simple lens. Hence the overall magnification M of the compound microscope is, apart from a negative sign, which is customarily ignored, ( M=m_{1} M_{2}=frac{(25 c m) S_{1}^{prime}}{f} )
1. What is the resolving power of the instrument whose magnifying power is given in the passage?
A ( cdot frac{mu sin theta}{0.61 lambda} )
в. ( frac{mu sin theta}{1.22 lambda} )
c. ( frac{mu sin theta}{lambda} )
D. ( frac{sin theta}{1.22 lambda} )
12
268Two plane wavefronts of light, one
incident on a thin convex lens and
another on the refracting face of a thin prism. After refraction at them, the emerging wavefronts respectively become
A. plane wavefront and plane wavefront
B. plane wavefront and spherical wavefront
c. spherical wavefront and plane wavefront
D. spherical wavefront and spherical wavefront
E . elliptical wavefront and spherical wavefront
12
269The device which produces highly coherent sources is
A. Fresnel biprism
B. Young’s double sitt
c. Laser
D. Lloyd’s mirror
12
270Unpolarised light of intensity
( 32 W m^{-2} ) passes through three polarizers such that transmission axis of first is crossed with third. If intensity
of emerging light is ( 2 W m^{-2} ), what is the angle of transmission axis between
the first two polarisers?
( A cdot 30 )
B . 45
( c cdot 22.5 )
D. ( 60^{circ} )
12
2717. In a YDSE bichromatic lights of wavelengths 400 nm
and 560 nm are used. The distance between the slits is
0.1 mm and the distance between the plane of the slits
and the screen is 1 m. The minimum distance between
two successive regions of complete darkness is
(a) 4 mm
(b) 5.6 mm
(c) 14 mm
(d) 28 mm
12
272( ln ) YDSE, ( d=2 m m, D=2 m ) and ( lambda= )
( 500 n m . ) If intensities of two slits are ( I_{0} )
and ( 9 I_{0}, ) then find intensity at ( y= )
( frac{1}{6} m m )
A ( cdot 7 I_{0} )
в. ( 10 I_{0} )
( c cdot 16 I_{0} )
D. ( 4 I_{0} )
12
27335. A double-slit experiment is immersed in a liquid of
refractive index 1.33. It has slit separation of 1 mm and
distance between the plane of slits and screen is 1.33 m.
The slits are illuminated by a parallel beam of light whose
wavelength in air is 6830 Å. Then the fringe width is
(a) 6.3 x 104
m m (b) 8.3 x 104 m
(c) 6.3 x 10-2 m
(d) 6.3 x 10 m
12
274In YDSE, find the missing wavelength at ( boldsymbol{y}=boldsymbol{d}, ) where symbols have their usual meaning (take ( D>>d ) ).
( ^{mathrm{A}} cdot frac{d^{2}}{D} )
B. ( frac{2 d^{2}}{7 D} )
c. ( frac{3 d^{2}}{D} )
D. ( frac{d^{2}}{3 D} )
12
275The wave fronts of light wave traveling in vacuum are given by ( boldsymbol{x}+boldsymbol{y}+boldsymbol{z}=boldsymbol{c} )
The angle made by the light ray with the X-axis is:
A ( cdot 0^{circ} )
B . ( 45^{circ} )
( c cdot 90^{circ} )
D. ( cos ^{-1} frac{1}{sqrt{3}} )
12
27611. White light may be considered to be a mixture of waves
with 2 ranging between 3900 Å and 7800 A. An oil film
of thickness 10000 Å is examined normally by reflected
light. If u = 1.4, then the film appears bright for
(a) 4308 Å, 5091 A, 6222 Å
(b) 4000 Å, 5091 Å, 5600 Å
(c) 4667 Å, 6222 Å, 7000 Å
(d) 4000 Å, 4667 Å, 5600 Å, 7000 Å
12
277A red flower when viewed through blue light appears:
A . red
B. blue
c. black
D. violet
12
27855. A beam of natural light falls on a system of 6 polaroids,
which are arranged in succession such that each polaroid
is turned through 30′ with respect to the preceding one.
The percentage of incident intensity that passes through
the system will be
(a) 100%
(b) 50%
(c) 30%
(d) 12%
12
279Two Polaroids ( P_{1} ) and ( P_{2} ) are placed with their axis perpendicular to each other.
Unpolarized light ( l_{0} ) is incident on ( P_{1} . A )
third polaroid ( P_{3} ) is kept in between ( P_{1} )
and ( P_{2} ) such that its axis makes an
angle ( 45^{circ} ) with that of ( P_{1} . ) The intensity
of transmitted light through ( P_{2} ) is
A ( cdot frac{I_{0}}{2} )
B. ( frac{I_{0}}{4} )
( c cdot frac{I_{0}}{8} )
D. ( frac{1}{16} )
12
280A: In interference pattern, intensity of
successive fringes due to achromatic light is not same.
R: In interference, only redistribution of
energy takes place.
A. Both A and R are true, and R is correct explanation of
B. Both A and R are true, and R is not correct explanation of A
c. A is true but R is false
D. A is false but R is true
12
281The intensity at the maximum in a
Young’s double slit experiment is ( boldsymbol{I}_{0} )
Distance between two slits is ( boldsymbol{d}=mathbf{5} boldsymbol{lambda} )
where ( lambda ) is the wavelength of light used
in the experiment. What will be the intensity in front of one of the slits on
the screen placed at a distance ( D= )
( 10 d ? )
( mathbf{A} cdot I_{0} )
в. ( frac{I_{0}}{4} )
c. ( frac{3}{4} I_{0} )
D. ( frac{I_{0}}{2} )
12
282A plane wavefront ( A_{1} B_{1} ) is incident at a
boundary ( A_{1} B_{2} ) as shown. It takes time
( tau ) for the wavefront to travel from ( B_{1} ) to
( B_{2} . ) Speeds of propagation of light in
medium 1 and 2 are ( v_{1} ) and ( v_{2} )
respectively and ( v_{2}>v_{1} . ) For the total
internal reflection of wavefront.
( mathbf{A} cdot v_{1} tau>A_{1} B_{2} )
B . ( v_{2} tau>A_{1} B_{2} )
c. ( v_{1} tau<A_{1} B_{2} )
D. ( v_{2} tau<A_{1} B_{2} )
12
283State whether true or false:
During constructive interference, the crest of one wave meets the crest of the
other wave or the trough of one wave
meets the trough of the other wave.
A. True
B. False
12
284the central bright maxima is twice as wide as the other maxima.12
285A source ( S ) and a detector ( D ) of high
frequency waves are a distance d apart
on the ground. The direct wave from S is found to be in phase at D with the wave
from ( S ) that is reflected rays make the
same angle with the reflecting layer. When the layer rises a distance ( h, ) no
signal is detected at D. Neglect absorption in the atmosphere and find the relation between ( mathrm{d}, mathrm{h}, mathrm{H} ) and the wavelength ( lambda ) of the waves.
12
286Use Huygen’s principle to show how a plane wavelength propagates from a denser to rarer medium. Hence verify
Snell’s law of refraction
12
287Two small loud speakers ( A ) and ( B ) are
driven by the same amplifier as shown in Fig and emit pure sinusoidal waves in phase. Speaker ( A ) is ( 1 mathrm{m} ) away as
shown and speaker ( B ) is 2 m away from
the amplifier. The microphone is ( 4 mathrm{m} )
away from the amplifier in transverse direction as indicated in the Figure. For
what frequencies constructive interference will occur at ( boldsymbol{P} )
(microphone point)
B. 500 Нz, 1500 нz
c. 550 Нz, 1100 Н ( z_{text {… }} )
D. 500 нz, 1000 Нz,1500 нz
12
2883. Light waves travel in vacuum along the y-axis. Which of
the following may represent the wavefront?
(a) x = constant
(b) y = constant
(c) z= constant
(d) x + y + z = constant
12
289From Brewster’s law, it follows that the
angle of polarization depends upon
A. the wavelength of light
B. orientation of the plane of polarization
c. orientation of the plane of vibration
D. none of these
12
290The two lenses of an achromatic
doublet should have:
A. Equal powers
B. Equal dispersive powers
C. Equal ratio of their power and dispersive power
D. Sum of the product of their powers and dispersive power equal to zero
12
291A convex lens of diameter ( 8 mathrm{cm} ) is used
to focus a parallel beam of light of wavelength ( 620 n m . ) Light is focused at a distance ( 20 c m, ) from the lens. What would be the radius of central bright fringe?
12
292Unpolarised light is passed through a
polaroid ( P_{1} . ) When this polarised beam
passes through another polaroid ( P_{2} ) and
if the pass axis of ( boldsymbol{P}_{2} ) makes angle ( boldsymbol{theta} )
with the pass axis of ( P_{1} ), then write the expression of intensity for the polarised
beam passing through ( P_{2} . ) Draw a plot showing the variation of intensity when ( theta ) varies from 0 to ( 2 pi )
12
293A single slit of width ( a ) is illuminated by violet light of wave length 400 nm and
width of the diffraction pattern is measured as ( y ). Half of the slit is
covered and illuminated with 600 nm.
The width of the diffraction pattern will be
A ( cdot frac{y}{3} )
B. pattern vanishes and width is zero
c. ( 3 y )
D. none of these
12
29442. Angular width (B) of central maximum of a diffraction
pattern on a single slit does not depend upon
(a) distance between slit and screen
(b) wavelength of light used
(c) width of the slit
(d) frequency of light used
12
295What is a wavefront? How does it
propagate ? Using Huygens’ principle, explain reflection of a plane wavefront
from a surface and verify the laws of
reflection.
12
296In Youngs double slit experiment, the
slits are ( 2 m m ) apart and are
¡IIluminated with a mixture of two
wavelengths ( lambda=12000 A^{circ} ) and ( lambda= )
( 10000 A^{circ} . ) At what minimum distance
from the common central bright fringe
on a screen ( 2 m ) from the slits will a
bright fringe from one interference
coincide with a bright fringe from the other?
A. ( 3.2 mathrm{mm} )
B. ( 6.0 mathrm{mm} )
c. ( 7.2 mathrm{mm} )
D. ( 9.2 mathrm{mm} )
12
297A plane polarized light is incident normally on a tourmaline plate. Its ( overrightarrow{boldsymbol{E}} )
vectors make an angle of ( 60^{circ} ) with the
optic axis of the plate. Find the percentage difference between initial and final intensities.
A . ( 25 % )
B . 50%
c. ( 75 % )
D. 90%
12
298If in an unpolarised light ( mathrm{E}=2 vec{i}+3 vec{j} ) and ( vec{H}=3 vec{i}-2 vec{j}, ) then the direction of
propagation is given by
A ( -13 vec{k} )
the ( -13 vec{k} ).
B . ( -13 vec{j} )
( mathbf{c} cdot-6 vec{i}+6 vec{k} )
D. ( 5 vec{i}-4 vec{k} )
12
299When unpolarized light beams are incidents in the air into glass ( (n=1.5 ) at polarising angle)
A. reflected beams is 100 polarised
B. reflect and refracted beams are partially polarised
c. the reason for
(a) is that almost all the light is reflected
D. all the above
12
300On the basis of Huygen’s Wave theory of light, show that angle of reflection is equal to angle of incidence. You must
draw a labelled diagram for this derivation.
12
301What is the path difference for destructive interference?
A ( cdot frac{(2 n+1) lambda}{2} )
B. ( frac{(n+1) lambda}{2} )
c. ( n(lambda+1) )
D. ( n lambda )
12
302A diffraction pattern is obtained by making blue light incident on a narrow slit. If blue light is replaced by red light, then the diffraction bands
A. disappear
c. become narrower
D. remain same
12
303At the polarising angle ( left(boldsymbol{theta}_{B}right), ) angle of refraction is given by :
A ( .90^{circ} )
В. ( 90^{circ}+theta_{B} )
c. ( 90^{circ}-theta_{B} )
D. ( frac{90^{circ}}{theta_{B}} )
12
30411. A mixture of lights, consisting of wavelength 590 nm and
an unknown wavelength illuminates Young’s double slit
and gives rise to two overlapping interference patterns on
the screen. The central maximum of both lights coincide.
Further, it is observed that the third bright fringe of the
known light coincides with the fourth bright fringe of
the unknown light. From this data, the wavelength of the
unknown light is
(a) 393.4 nm
(b) 885.0 nm
(c) 442.5 nm
(d) 776.8 nm (AIEEE 2009)
12
305Assume 100 pm ( X ) -ray beam is passed through YDSE. Interference pattern is observed on a photographic plate placed ( 40 mathrm{cm} ) away from the slits. What should be the separation between the slits so that the separation between two successive maxima is ( 0.1 mathrm{mm} )
A ( .4 mu m )
в. ( 0.4 mu m )
( c .4 n m )
D. ( 40 mu m )
12
306Making a light wave vibrate in only one plane is known as:
A. refraction
B. reflection
c. Interference
D. diffraction
E. polarization.
12
307happens when two or more waves
overlap.
12
308The condition for destructive
interference is path difference should
be equal to :
A. odd integral multiple of wavelength
B. Integral multiple of wavelength
c. odd integral multiple of half wavelength
D. Integral multiple of half wavelength
12
309Light of wavelength ( lambda_{0} ) in air enters a
medium of refractive index ( n . ) If two
points ( A ) and ( B ) in this medium lid
along the path of this light at a distance
( x, ) then phase difference ( phi_{0} ) between
these two points is
( ^{mathbf{A}} cdot_{0}=frac{1}{n}left(frac{2 pi}{lambda_{0}}right) x )
B ( cdot_{phi_{0}}=nleft(frac{2 pi}{lambda_{0}}right) x )
( ^{mathbf{c}} cdot_{phi_{0}}=(n-1)left(frac{2 pi}{lambda_{0}}right) x )
D ( , quad phi_{0}=frac{1}{(n-1)}left(frac{2 pi}{lambda_{0}}right) x )
12
310Why are coherent sources required to create interference of light?12
31123. In a Young’s double slit experiment, slits are separ
by 0.5 mm, and the screen is placed 150 cm away
beam of light consisting of two wavelengths, 650 nm
and 520 nm, is used to obtain interference fringes on
the screen. The least distance from the common central
maximum to the point where the bright fringes due to
both the wavelengths coincide is
(a) 9.75 mm
(b) 15.6 mm
(c) 1.56 mm
(d) 7.8 mm
(JEE Main 2017)
12
312Wave front means:
A. all particles in it have same phase
B. few particles are in same phase, rest are in opposite phase
C . all particles have opposite phase of vibrations
D. all particles have random vibrations
12
313Using Huygen’s wave theory, derive Snell’s law of refraction.12
314Why does light from a clear blue portion of the sky show a rise and fall of intensity when viewed through a polaroid which is rotated? Explain by drawing the necessary diagram.12
315An arrangement for YDSE is shown in
figure. S is a light source then find the
position of central maxima from point 0
on screen B.
A. ( 5 mathrm{mm} ) below
B. ( 5 mathrm{mm} ) above 0
c. ( 30 mathrm{mm} ) below
( D cdot alpha )
12
316If the polarizing angle of a piece of glass
for green light is ( 54.74^{circ}, ) then the angle of minimum deviation for an equilateral prism made of same glass is :
( left[mathrm{GIVEN}, tan 54.74^{circ}=1.414right] )
A ( cdot 45^{circ} )
B. 54.74
( c cdot 60 )
( D cdot 30^{circ} )
12
317In a double-slit experiment the angular
width of a fringe is found to be ( 0.2^{circ} ) on a
screen placed 1 m away. The
wavelength of light used is ( 600 n m ) What will be the angular width of the fringe is the entire experimental apparatus is immersed in water? Take refractive index of water to be ( frac{4}{3} )
12
318ASSERTION (A):Hyugens’ theory failed to explain polarization

REASON (R): According to Hyugens’ theory light is longitudinal wave
A. A is correct, R is correct and it is the correct explanation
B. A is correct, R is correct but it is not a correct explanation
c. A is correct, R is wrong
D. A is wrong, R is correct

12
319Two superimposing waves are
represented by equation ( boldsymbol{y}_{1}= )
( 2 sin 2 pi(10 t-0.4 x) ) and ( y_{2}= )
( 4 sin 2 pi(20 t-0.8 x) . ) The ratio of ( I_{max } ) to
( boldsymbol{I}_{m i n} )
( mathbf{A} cdot 36: 4 )
B. 25: 9
( c cdot 1: 4 )
D. 4: 1
12
320Two coherent monochromatic light beams of intensities ( I ) and ( 4 I ) are
superposed. The maximum and minimum possible resulting intensities
are :
A ( .5 I ) and 0
B. ( 5 I ) and ( 3 I )
c. ( 9 I ) and ( I )
D. ( 9 I ) and ( 3 I )
12
321A slit of width ( a ) is illuminated by a
monochromatic light of wavelength ( mathbf{6 5 0} ) nm. The value of ( a ) when the first
minima falls at an angle of diffraction
of ( 30^{0} ) is
A. ( 1.3 times 10^{-6} m )
B . ( 2.6 times 10^{-6} m )
c. ( 3.9 times 10^{-6} mathrm{m} )
D. ( 5.2 times 10^{-6} m )
12
322The condition for obtaining secondary maxima in the diffraction pattern due to single slit is (symbols have their usual meaning)
( A cdot a sin theta=n lambda )
B. ( a sin theta=(2 n-1) frac{lambda}{2} )
( c cdot a sin theta=(2 n-1) lambda )
D. ( a sin theta=frac{n lambda}{2} )
12
323The phases of the light wave at ( mathbf{c}, mathbf{d}, mathbf{e} )
and ( mathbf{f} ) are ( phi_{mathrm{c}}, phi_{mathrm{d}}, phi_{mathrm{e}} ) and ( phi_{mathrm{f}} ) respectively.
It is given that ( phi_{mathrm{c}} neq phi_{mathrm{f}} )
A ( cdot phi_{mathrm{c}} ) cannot be equal to ( phi_{mathrm{d}} )
B. ( phi_{mathrm{d}} ) can be equal to ( phi_{mathrm{e}} )
C ( cdotleft(phi_{mathrm{d}}-phi_{mathrm{f}}right) ) is equal to ( left(phi_{mathrm{c}}-phi_{mathrm{e}}right) )
( mathbf{D} cdotleft(phi_{mathrm{d}}-phi_{mathrm{c}}right) ) is not equal to ( left(phi_{mathrm{f}}-phi_{mathrm{e}}right) )
12
324A parallel beam of natural light is
incident at an angle of ( 58^{circ} ) on a plane glass surface. The reflected beam is
completely linearly polarized(tan ( 58^{circ}= )
1.6). The angle of refraction of the transmitted beam and the refractive
index of the glass are :
A ( cdot 32^{circ}, 1.6 )
B. 3.2^,1.6
c. ( 32^{circ}, 1.3 )
D. 3.2?, 1.3
12
325In an interference pattern produced by
two identical slits, the intensity at the
site of the central maximum is I. The
intensity at the same spot when either
of the two slits is closed is ( I_{0} ). We must
have:
( mathbf{A} cdot I=I_{0} )
в. ( I=2 I_{0} )
c. ( I=4 I_{0} )
D. ( I ) and ( I_{circ} ) are not related
12
326A monochromatic beam of light falls on Young’s double slit experiment
apparatus as shown in figure. A thin
sheet of glass is inserted .in front of
lower slit ( S_{2} )
The central bright fringe can be
obtained:
( A cdot A t O )
B. Above ( O )
c. Below ( O )
D. Anywhere depending on angle ( theta ), thickness of plate ( t ), and refractive index of glass ( mu )
12
32763. Light of wavelength 2 = 5890 Å falls on a double-slit
arrangement having separation d=0.2 mm. Athin lens of focal
length f= 1 mis placed near the slits. The linear separation
of fringes on a screen placed in the focal plane of the lens is
(a) 3 mm
(b) 4 mm
(c) 2 mm
(d) 1 mm
C 1
1
11
12
328Two polaroids are kept crossed to each other. If one of them is rotated an angle
( 60^{circ}, ) the percentage of incident light now transmitted through the system is
A . 10%
B. 20%
c. 25%
D. 12.5%
12
329Two sources of light of wavelengths ( 2500 A ) and ( 3500 A ) are used in Young’s
double slit experiment simultaneously. Which orders of fringes of two wavelength patterns coincide?
A. 3 rd order of 1 st source and 5 th of the 2 nd
B. 7th order of 1st and 5th order of 2nd
c. 5 th order of 1 st and 3 rd order of 2 nd
D. 5 th order of 1 st and 7 th order of 2 nd
12
330State the two laws of reflection of light.12
331In Young’s double slit experiment, distance between two slits is ( 0.28 mathrm{mm} )
and distance between slits and screen
is ( 1.4 mathrm{m} ). Distance between central bright hinge and third bright fringe is ( 0.9 mathrm{cm}, ) what is the wavelength of light used?
A ( .4000 A^{circ} )
в. ( 6000 A^{circ} )
c. ( 3000 A^{circ} )
D. ( 5000 A^{circ} )
12
332Two coherent monochromatic light
beams of intensities ( I ) and ( 4 I ) are
superposed. The maximum and minimum possible intensities in the resulting beam are:
A. ( 5 I ) and ( I )
B. ( 5 I ) and ( 3 I )
c. ( 9 I ) and ( I )
D. ( 9 I ) and ( 3 I )
12
333A and ( mathrm{B} ) are facing the mirror and
standing in such a way that ( A ) can see ( B )
and ( B ) can see A. Explain this
phenomenon.
12
334When light suffers reflection at the
interface between water and glass, the change of phase in the reflected wave is
A. zero
в. ( pi )
( c cdot pi / 2 )
D. 2 ( pi )
12
335A plane wave of monochromatic light falls normally on a uniformly thin film of oil which covers a glass plate. The wavelength of source constructive interference is observed for ( lambda_{1}=5000 stackrel{circ}{A} ) and ( lambda_{2}=10000 A ) and for no other
wavelength in between. If ( mu ) of oil is 1.25
and that of glass is ( 1.5, ) the thickness of film will be
A . 0.2
B. 0.1
( c .0 .8 )
D. 0.4
12
336Unpolarised light is passed through a
polaroid ( P_{1} ).When this polarised beam
passes through another polaroid ( P_{2} ) and
if the pass axis of ( P_{2} ) makes angle ( theta )
with the pass axis of ( P_{1} ). then write the
intensity when ( theta ) varies from 0 to ( 2 pi )
12
337Name the physical quantity which
remains same for microwaves ( 1 mathrm{mm} )
and UV radiation of ( 6000_{A}^{circ} ) in a vacuum
12
338( lambda_{a} ) and ( lambda_{m} ) are the wavelengths of a
beam of light in air and medium respectively. If ( theta ) is the polarising angle, the correct relation between ( lambda_{a}, lambda_{m} ) and
( boldsymbol{theta} ) is:
A ( cdot lambda_{a}=lambda_{m} tan ^{2} theta )
B ( cdot lambda_{m}=lambda_{a} tan ^{2} theta )
( mathbf{c} cdot lambda_{a}=lambda_{m} cot theta )
D. ( lambda_{m}=lambda_{a} cot theta )
12
339Can white light produce interference?
What is the nature?
12
340In Young’s double slit experiment the distance between two slits is ( 2 m m ) and
screen is at a distance of ( 120 mathrm{cm} ) from
the plane of slits. The smallest distance from the central maxima where the
bright fringe due to light of wavelength
( 6500 A^{circ} ) and ( 5200 A^{circ} ) would coincide?
A ( .0 .156 mathrm{cm} )
B. ( 0.186 mathrm{cm} )
c. ( 0.486 mathrm{cm} )
D. ( 0.456 mathrm{cm} )
12
341If ( boldsymbol{d}=mathbf{0 . 5 m m}, boldsymbol{lambda}=mathbf{5 0 0 0} boldsymbol{A} ) and ( boldsymbol{D}= )
100 ( c m ), find the value of ( n ) for the
closest second bright ring.
( A cdot 888 )
В. 83
( c .914 )
D. 998
12
342What is meant by diffraction of light?12
343The interference pattern with two
coherent light sources of density ratio ( n ) In the interference pattern, the ratio ( frac{boldsymbol{I}_{m a x}-boldsymbol{I}_{m i n}}{boldsymbol{I}_{m a x}+boldsymbol{I}_{m i n}} ) will be:
A. ( frac{sqrt{n}}{n+1} )
B. ( frac{2 sqrt{n}}{n+1} )
c. ( frac{sqrt{n}}{(n+1)^{2}} )
D. ( frac{2 sqrt{n}}{(n+1)^{2}} )
12
34420. In Young’s double-slit experiment, the slits are illuminated
by monochromatic light. The entire set-up is immersed
in pure water. Which of the following act cannot restore
the original fringe width?
(a) Bringing the slits close together.
(b) Moving the screen away from the slit plane.
(c) Replacing the incident light by that of longer
wavelength.
(d) Introducing a thin transparent slab in front of one of
the slits.
12
345If the frequency of the source is doubled in Young’s double slit experiment, then fringe width ( (boldsymbol{beta}) ) will be-
A. unchanged
B. ( beta / 2 )
( c cdot 2 beta )
D. ( 3 beta )
12
346In a Young’s double slit experiment, the path different, at a certain point on the screen, between two interfering waves is ( frac{1}{8} t h ) of wavelength. The ratio of the intensity at this point to that at the centre of a brigth fringe is close to :
A .0 .94
в. 0.74
c. 0.85
D. 0.80
12
347The air film in a Newton’s ring apparatus is replaced by an oil film. The radii of the rings
A. remains the same
B. increases
c. decreases
D. none of the above
12
348In Young’s double slit experiment shows
in figure, ( S_{1} ) and ( S_{2} ) are coherent
sources and ( mathrm{S} ) is the screen having a
hole at a point ( 1.0 mathrm{mm} ) away from the
central line. White light ( (400 text { to } 700 ) nm)
is sent through the slits. Which
wavelength passing through the hole
has the strongest intensity?
A. ( 400 mathrm{nm} )
B. 700 nm
( c .500 mathrm{nm} )
D. 667 nm
12
349Draw the intensity pattern for single slit diffraction and double slit interference.
Hence state two differences between
interference and diffraction patterns.
12
350In a simple slit diffraction pattern intensity and width of fringes are
A. Unequal width
B. Equal width
c. Equal width and equal intensity
D. Unequal width and unequal intensity
12
351In Young’s double slit experiment, separation between the slits is halved
and distance between slits and screen
is doubled. The fringe width is
A. same
c. halved
D. one-third
12
35274. Light from a source emitting two wavelengths , and 2,
is allowed to fall on Young’s double-slit apparatus after
filtering one of the wavelengths. The position of interfer-
ence maxima is noted. When the filter is removed both the
wavelengths are incident and it is found that maximum
intensity is produced where the fourth maxima occured
previously. If the other wavelength is filtered, at the same
location the third maxima is found. What is the ratio of
wavelengths?
In
ma
(d)
(a)
12
353In Young’s double slit experiment, interference pattern will not be seen if
one uses
A. a LASER as the source of light
B. two LASER sources in front of two slits
c. two sodium light lamps in front of two slits
D. in both (b) and (c) above
12
354Albert Einstein used corpuscular theory to explain:
A ( . E=m c^{2} )
B. The photoelectric effect
c. Quantisation of charge
D. magic of light
12
355Two points sources separated by ( 2.0 m )
are radiating in phase with ( lambda=0.50 m )
A detector moves in a circular path
around the two sources in a plane
containing them. How many maxima
are detected?
( A cdot 16 )
B . 20
( c cdot 24 )
D. 32
12
356Monochromatic light of wavelength
( 4500 A ) falls on slit of width ‘a’. In
diffraction pattern second maxima
deviates through ( 30^{circ} . ) The slit width is
( mathbf{A} cdot 900 stackrel{circ}{A} )
в. 18000 А
( mathrm{c} cdot_{13500 AA} )
D ( cdot 22500 ) 台
12
357A thin film with index of refraction 1.50
coats a glass lens with index of
refraction ( 1.80 . ) What is the minimum
thickness of the film that will strongly
reflect light with wavelength 600 nm?
A . ( 150 mathrm{nm} )
B. ( 200 n m )
c. 300 nm
D. ( 450 n m )
12
358White light is incident normally on a soap film of thickness ( 15 times 10^{-5} mathrm{cm} )
and refractive index ( 1.33 . ) Which
wavelength is reflected maximum in the visible region?
A ( .26000 A^{circ} )
B. ( 8866 A^{circ} )
c. ( 5320 A^{circ} )
D. ( 3800 A^{circ} )
12
359Which of the following statements is
correct?
A. Diffraction is because of interference of light from same sources whereas interference is due to light form two isolated sources.
B. Diffraction is due to interaction of light from same wave fronts whereas interference is due to interaction
of two waves derived from the same source.
C. Diffraction is due to interference of waves derived from the same source whereas interference is bending of light from the same source
D. Diffraction is due to reflected waves whereas interference is due to transmitted waves from a
source.
12
360A parallel beam of light ( lambda=5000 A^{circ} )
falls normally on a single narrow slit of
width ( 0.001 m m . ) The light is focused by a convex lens on a screen placed in the focal plane. The first minimum will be
formed for the angle of diffraction are equal to:
A . ( 0^{circ} )
В. ( 15^{circ} )
( c cdot 30^{0} )
D. ( 50^{circ} )
12
361Distinguish between the phenomenon of interference and diffraction of light.12
362In producing a pure spectrum, the
incident light is passed through a
narrow slit placed in the focal plane of
an achromatic lens because a narrow
slit
A. produce less diffraction
B. increase intensity
C. allows only one colour at a time
D. allows a more parallel beam when it passes through the lens.
12
363The intensity of the light coming from one of the slits in YDSE is double the
intensity from the other slit. Find the ratio of the maximum intensity to minimum intensity in the interference fringe pattern observed
( A cdot 32 )
B. 34
( c .36 )
D. 38
12
Youngs double slit apparatus. The
separation between maxima is
measured on a screen placed parallel to
the plane of the slits at a distance of
1.0 ( m ) from it as shown in figure. The
separation between the slits is ( 2 d= )
1 ( m m )
(a) If the incident beam falls normally on the double slit apparatus, find the ( y- ) coordinates of all the interface
minima of the screen
(b) If the incident beam makes an angle
of ( 30^{circ} ) with the ( x- ) axis (as shown in fig)
find the ( y- ) coordinates of the first
minima on either side of the central
maximum.
12
365In conventional light sources:
A. different atoms emit radiation at different times
B. there is no phase relation between the emitted photons
C. different atoms emit photon in different direction
D. all of the above
12
366A parallel beam of diameter ( d ) is
incident on air-glass interface as shown
in figure. The diameter of refracted light beam is :
( left(d=3 m m, theta=45^{circ} text { and } frac{n_{g l a s s}}{n_{a i r}}=frac{3}{2}right) )
A . ( sqrt{12} ) mm
B. ( sqrt{14} ) mm
( c cdot sqrt{6} m m )
D. ( 4.5 mathrm{mm} )
12
367A polnt sources ( boldsymbol{s} ) emicting IIght of
wavelength 600 nm is placed at a very
small height ( h ) above a flat reflecting
surface ( boldsymbol{A B} ) (see figure). The intensity
of the reflected light is ( 36 % ) of the
incident intensity. Interference fringes
are observed on a screen placed parallel
to the reflecting surface at a very large
distance ( D ) from it.What is the shape of
the interference fringes on the screen?
A. Circular
B. helical
C . eliptical
D. spiral
12
368In a Young’s double-slit interference experiment using a yellow light of wavelength ( lambda ), with the slits labelled ( S_{1} )
and ( S_{2} . ) If ( P ) is the centre of a dark
fringe on the screen on which the resulting diffraction pattern is
projected, Find out the equations
relating ( S_{1} P ) and ( S_{2} P ) which could be
true?
A ( cdot S_{1} P-S_{2} P=frac{1}{2 lambda} )
B . ( S_{1} P-S_{2} P=lambda )
c. ( S_{1} P-S_{2} P=2 lambda )
D. ( S_{1} P-S_{2} P=3 lambda )
E . ( S_{1} P=S_{2} P )
12
369Unpolarised light of intensity ( 32 mathrm{W} mathrm{m}^{-2} )
passes through three polarizes is crossed with that of the first. The
intensity of final emerging light is 3 ( mathrm{W} mathrm{m}^{-2} . ) The intensity of light transmitted by first polarizer will be
( A cdot 32 W m^{-2} )
B. ( 16 mathrm{W} mathrm{m}^{-2} )
( c cdot 8 w m^{-2} )
D. ( 4 mathrm{Wm}^{-2} )
12
370Which of the following statements
applies to light?
A. Light can only be described as particles.
B. Light can only be described as waves.
C. Light can be described as rays, waves and particles.
D. Light can only be described as rays.
12
371The angular width of the central maximum in a single slit diffraction
pattern is ( 60^{circ} . ) The width of the slit is 1
( mu mathrm{m} . ) The slit is illuminated by
monochromatic plane waves. If another slit of same width is made near it,
Young’s fringes can be observed on a
screen placed at a distance ( 50 mathrm{cm} ) from the slits. If the observed fringe width is
1cm, what is slit separation distance? (i.e., distance between the centres of each slit.)
A. ( 75 mu ) m
B. ( 100 mu ) m
c. ( 25 mu ) m
D. ( 50 mu ) m
12
372A stretched string is vibrating
according to the equation ( boldsymbol{y}= )
( 5 sin left(frac{pi x}{3}right) cos 400 pi t, ) where ( y ) and a are
in ( mathrm{cm} ) and ( t ) is second. Potential energy
will be zero at time t:-
A . 2 s
B. 4 s
( c cdot 8 s )
D. 16 s
12
373In the adjoining figure ( A, B, ) and ( C ) represents three progressive waves.
Which of the following statement about the waves is correct?
A ( cdot ) wave ( mathrm{C} ) lags behind in phase by ( frac{pi}{2} ) from ( mathrm{A} ) and ( mathrm{B} ) leads
by ( frac{pi}{2} )
B. Wave C leads in phase by ( pi ) from ( A ) and ( B ) lags behind by ( pi )
C. wave C leads in phase by ( frac{pi}{2} ) from A and lags behind by
( frac{pi}{2} )
D. Wave C lags behind in phase by ( pi ) from ( mathrm{A} ) and ( mathrm{B} ) leads by ( pi )
12
374If ( mu_{O} ) and ( mu_{e} ) are the refractive indices
of a double
refracting crystal, then
1) ( mu_{O}mu_{e} ) for calacite crystal
A. both 1 and 2 are true
B. 1 is true 2 is false
c. 1 false 2 is true
D. both 1 and 2 are false
12
375In biprism experiment a source of wavelength ( 6500 A ) is replaced by
source of wavelength ( 5500 A ). Calculate change in fringe width if the screen is
at, ( 1 mathrm{m} ) distance from the slits which are
1 mm apart.
12
37626. Young’s double-slit experiment is made in a liquid. The
10th bright fringe in liquid lies where 6th dark fringe
lies in vacuum. The refractive index of the liquid is
approximately
(a) 1.8
b (b) 1.54
(c) 1.67
(d) 1.2
12
377Plane polarized light is passed through a Polaroid. Now the Polaroid is given one complete rotation about the direction of light propagation. When viewed through another Polaroid (analyser), one of the following is observed:
A. The intensity of light gradually decreases to zero and then remains zero
B. The intensity of light becomes twice maximum and twice zero
c. The intensity of light becomes maximum and stays maximum
D. The intensity of light does not change
12
378Huygen’s concept of secondary wave
A. allows us to find the focal length of a thick lens
B. is a geometrical method to find a wavefront
( mathrm{C} ). is used to determine the velocity of light
D. is used to explain polarization
12
37912. The ratio of the intensity at the centre of a bright fringe to
the intensity at a point one-quarter of the distance between
two fringes from the centre is
(a) 2
(b) 1/2
(c) 4
(d) 16
12
380What is the Brewster angle for water?
The refractive index of water with
respect to air is 1.33
12
381After reflection from a concave mirror, a
plane wave front becomes
A. Cylindrical
B. Spherical
c. Remains planar
D. None of the above
12
382The ratio of maximum to minimum
intensity due to superposition of two waves is ( frac{49}{9} . ) Then the ratio of the intensity of component waves is :
A ( cdot frac{25}{4} )
в. ( frac{16}{25} )
c. ( frac{4}{49} )
D. ( frac{9}{49} )
12
383Which of the following generates a plane wavefront?
A ( . alpha- ) rays
B. ( beta- ) rays
c. ( gamma- ) rays
D. None of these
12
384Huygen’s concept of wavelets is useful
in
A. explaining polarisation
B. determining focal length of lenses
c. determining chromatic aberration
D. geometrical reconstruction of a wavefront
12
385A slit of width a is illuminated by the
red light of wavelength ( 6500 A^{0} . ) If the
first minimum falls at ( theta=30^{circ}, ) the value
of a is
A ( cdot 6.5 times 10^{-4} m m )
B. 1.3 micron
c. ( 3250 A^{circ} )
D. ( 2.6 times 10^{-4} mathrm{cm} )
12
386The correct relation between ( S, theta, L ) and
( C ) for an optically active solution is:
( mathbf{A} cdot S=theta L C )
B. ( theta=S L C )
( mathbf{c} . L=theta S C )
( mathbf{D} cdot C=theta L S )
12
387Light waves travel in vaccum along the
y-axis. Then the wave front is:
A. ( y= ) constant
B. ( x= ) constant
c. ( z= ) constant
D. ( x+y+z= ) constant
12
388State Huygen’s principle.12
389Assertion
In YDSE, if separation between the slits is less than wavelength of light, then no interference pattern can be observed.
Reason

For interference pattern to be observed, light sources have to be coherent.
A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Assertion is incorrect but Reason is correct

12
39031. In Young’s double-slit experiment, 12 fringes are observed
to be formed in a certain segment of the screen when light
of wavelength 600 nm is used. If the wavelength of light
is changed to 400 nm, the number of fringes observed in
the same segment of the screen is given by
(a) 12
(b) 18
(c) 24
(d) 30
12
391State whether true or false.
Light is a form of energy that causes a sensation of smell.
A. True
B. False
12
392The correct statement from the
following is:
A. Light exhibits particle nature in propagation and wave nature in mutual interaction with matter.
B. Light exhibits both wave nature and particle nature in mutual interaction with matter.
C. Light exhibits both wave and particle nature in propagation.
D. Light exhibits wave nature in propagation and particle nature in mutual interaction with matter
12
393At polarising angle, the angle between the reflected ray and refracted ray from a surface12
394Determine the separation between 1st and 2 nd dark fringes from the left end air cavity.
A ( cdot frac{3 L}{7}+frac{2 lambda_{0}}{mu} )
B. ( frac{5 L}{7} )
c. ( frac{4 L}{7} )
D. ( frac{6 L}{7} )
12
395The intensity falls as we move to
successive maxima away from the centre on either side.
12
396Unpolarized light of intensity ( boldsymbol{I}_{0} ) is incident on surface of a block of a glass
of Brewster’s angle. In that case, which one of the following statement is true?
A. transmitted light is partially polarized with intensity ( I_{0} / 2 )
B. transmitted light is completely polarized with intensity less than ( I_{0} / 2 )
C . reflected light is partially polarized with intensity ( I_{0} / 2 )
D. reflected light is completely polarized with intensity less than ( I_{0} / 2 )
12
397Two coherent light beams of intensity and 41 are superposed. The maximum and minimum possible intensities in the resulting beam are.
A. 9| and |
B. 9I and 31
c. 5 । and 1
D. 5 । and 3 ।
12
398Name a phenomenon or an experiment
which proves:
(i) Particle nature of electro magnetic
(ii) Wave nature of particles. (Description of the phenomenon experiment is not required)
12
399With the help of an experiment, state how will you identify whether a given beam of light is polarised or unpolarised.12
400In above shown figure, fringe pattern is produced by a monochromatic light passing through two narrow slit. If the fringe width is ( 2 mathrm{cm} ) then, which of the following changes would increase the distance between the bands?
A. Moving the slits closer together
B. Making the light source brighter
c. Moving the slits closer to the screen
D. Increasing the frequency of the light
E. shortening the wavelength of the light
12
401A: The corpuscular theory fails in explaining the velocities of light in air and water.
B: According to corpuscular theory, the light should travel faster in a ‘denser medium than in a rarer medium.
A. If both A and B are true but the B is the correct explanation of A
B. If both A and B are true but the B is not the correct explanation of A
c. If A is true but B is false
D. If both the A and B are false
E. If B is true but A is false
12
402A light ray is incident on a glass slab it is partially reflected and partially transmitted. Then the reflected ray is
A. completely polarised and highly intense.
B. partially polarised and poorly intense
c. partially polarised and highly intense
D. completely polarised and poorly intense.
12
403Which of the following properties shows that light is a transverse wave?
A. Reflection
B. Interference
c. Diffraction
D. Polarization
12
404The wave front is a surface in which:
A. All points are in the same phase
B. There is a pair of points in opposite phase
C there is a pair of points with phase difference ( left(frac{pi}{2}right) )
D. There is no relation between the phase
12
405( ln Y D S E, d=2 m m, D=2 m ) and
( lambda=500 n m . ) If intensity of two slits are
( l_{0} ) and ( 9 l_{0}, ) then find the intensity at ( boldsymbol{y}=frac{1}{6} boldsymbol{m m} )
A ( .7 l_{0} )
B. ( 10 l_{0} )
c. ( 16 l_{0} )
D. ( 4 l_{0} )
12
406Constructive interference is the method
of superimposing waves which has a phase difference of ( pi / 2 ) rads.
A. True
B. False
12
407Two waves of intensities ( I ) and ( 4 I )
produce interference. Then the
intensity of constructive and destructive interferences respectively
are
A. ( 3 I, 5 I )
B. ( 5 I, 3 I )
c. ( I, 9 I )
D. ( 9 I, I )
12
408In a double-slit experiment, instead of taking slits of equal width, one slit is made twice as wide as the other. Then
in the interference pattern
A. the intensities of both the maxima and the minima increase
B. the intensity of the maxima increases and the minima has zero intensity
c. the intensity of the maxima decreases and that of the minima increases
D. the intensity of the maxima decreases and the minima has zero intensity
12
4094. The maximum intensity in Young’s double slit experi
is 1o. Distance between the slits is d = 52, wher
the wavelength of monochromatic light used in the
experiment. What will be the intensity of light in front of
one of the slits on a screen at a distance D = 10 d
(b) 1
(c) 10
12
410The transverse nature of light waves is verified by
A. reflection of light
B. polarisation of light
c. refraction of light
D. interference of light
12
411A beam of light consisting of two
wavelengths, ( 650 mathrm{nm} ) and ( 520 mathrm{nm} ) is
used to obtain interference fringes in a Youngs double-slit experiment. What is the least distance from the central
maximum where the bright fringes due to both the wavelengths coincide?
A . ( 1.17 mathrm{mm} )
B. 2.52 mm
c. ( 1.56 mathrm{mm} )
D. 3.14 mm
12
412fa minima is formed at the detector, then the magnitude of wavelength ( lambda ) of the wave produced is given by
A ( .2 pi R )
в. ( frac{3}{2} pi R )
c. ( frac{5}{2} pi )
D. none of these
12
( S_{1} ) and ( S_{2} ), separated by distance ( 2.5 mathrm{m} )
are emitting in phase waves of wavelength ( 1 mathrm{m} . ) A detector moves in a large circular path around the two sources in a plane containing them. The number of maxima that will be detected
by it over the complete circular path,
are
A . 16
B. 12
( c cdot 10 )
D. 8
12
414Why do polarized sun glasses block out some reflected light (glare), but do not block out light that has not been reflected?
A. Some reflected light is at least partially polarizedd
B. Some reflected light changes frequency
c. Some reflected light is red-shifted
D. Some reflected light is at least partially diffracted
E. Some reflected light splits into multiple photons
12
415The shift of the interference pattern on
the screen when the slit is displayed by
( boldsymbol{S l}=mathbf{1} boldsymbol{m} boldsymbol{m} ) along the arc of radius ( boldsymbol{r} )
with centre at 0
( A cdot 4 m m )
B. ( 6 m m )
( c .10 m m )
D. ( 13 m m )
12
416Select the right one from the given
options.
A. Christian Huygens, a Contemporary of Newton established the Wave theory of light by assuming that light waves are transverse.
B. Maxwell provided the compelling theoretical evidence that light is transverse in nature.
C. Thomas Young experimentally proved the wave behavior of light and Huygens assumption.
D. All the statements given above are correct
12
417If instead of ( M g F_{2}, ) the coating of the substance whose refractive indices is
larger than the refractive index of glass
A. would not have occurred
B. would have occurred due to total internal reflection of light
c. would have occurred due to refraction of light
D. would have occurred due to strong reflection
12
41839. In YDSE, find the thickness of a glass slab (u=1.5) which
should be placed before the upper slit S, so that the central
maximum now lies at a point where 5th bright fringe was
lying earlier (before inserting the slab). Wavelength of
light used is 5000 Å.
(a) 5 x 100 m
(b) 3 x 10m
(c) 10 x 10 m m (d) 5 x 10-5 m
12
419What is diffraction of light?
A. The process where the incident light on a surface is bounced back into the same medium
B. Splitting of a ray of light into its 7 constituent colours is known as diffraction
C. The process by which a beam of light is spread out as a result of passing through a narrow aperture or across an edge,is known as diffraction
D. None of these
12
420A plane wave of wavelength ( 6250 A ) is incident normally on a slit of width ( 2 times )
( 10^{-2} mathrm{cm} . ) The width of the principle
maximum of diffraction pattern on a
screen at a distance of ( 50 mathrm{cm} ) will be:
A ( cdot 312 times 10^{-3} mathrm{cm} )
B . ( 312.5 times 10^{-4} mathrm{cm} )
c. 312 ст
D. ( 312.5 times 10^{-5} mathrm{cm} )
12
421Two Nicole prisms are kept perpendicular. One of them is illuminated with a light intensity
(natural) ( I_{o} ). Two more nicol prisms are introduced in between symmetrically. Find the light intensity emitted from the last nicol prism.
A ( cdot frac{27 I_{0}}{64} )
в. ( frac{27 I_{o}}{128_{o}} )
c. ( _{9} frac{I_{o}}{32} )
D. ( frac{9 I_{0}}{64} )
12
42210. The ratio of intensities of consecutive maxima in the
diffraction pattern due to a single slit is
(a) 1:4:9
(b) 1:2:3
4 4
(c) 1: –
972 2572
(a) 1:
72
12
423What is wavefront of light waves?12
424In a single slit diffraction experiment,
the width of the slit is made half the
original width
A. the width of the central maxima becomes double
B. the width of the central maxima becomes half
c. the width of the central maxima becomes one fourth
D. the width of the central maxima becomes four times
12
425Diffraction of sound is very easy, to observe in day-to-day life. This is not so with light. This is so because
( A cdot lambda_{S}>lambda_{L} )
в. ( lambda_{s}<lambda_{L} )
c. light waves are transverse and sound waves are longitudinal
D. ( lambda_{S}=lambda_{L} )
12
426Two point white dots are ( 1 mathrm{mm} ) apart on a black paper. They are viewed by eye of pupil diameter 3 mm. Approximately, what is the maximum distance at
which these dots can be resolved by the eye? [Take wave length of light =500 nm]
A . ( 10 mathrm{m} )
B. ( 5 mathrm{m} )
( c cdot 15 m )
D. None of these
12
42748. If in single slit diffraction pattern, first minima for red
light (600 nm) coincides with first maxima of some other
wavelength 2, then a would be
(a) 400 nm
(b) 440 nm
(c) 0.3 nm
(d) 900 nm
12
428Choose the correct statements among
the following given options.
A. Brewster’s angle is independent of wavelength of light.
B. Brewster’s angle is independent of the nature of reflecting surface.
C. Brewster’s angle is different for different wavelengths.
D. Brewsters angle depends on wavelength but not on the nature of reflecting surface.
12
429In Young’s double slit experiment, a
glass plate is placed before a slit which
absorbs half the intensity of light. Under
this case:
A. The brightness of fringes decreases
B. The fringes width decrease
C. No fringes will be observed
D. The bright fringes become fainter and the dark fringes have finite light intensity
12
430Which of the following statement is
false:
A. Sound and light wave exhibit interference
B. Sound and light wave exhibit diffraction
C. Light wave exhibits polarization while sound wave does not
D. Sound wave exhibits polarization while light wave does not
12
431In which of the following the final image
is erect?
A. Compound microscope
B. Astronomical telescope
c. simple microscope
D. All of the above
12
432Light from two coherent sources of the same amplitude ( A ) and wavelength ( lambda ) illuminates the screen. The intensity of
the central maximum is ( I_{0} . ) If the
sources were incoherent, the intensity at the same point will be.
A . ( 4 I_{0} )
в. ( 1 I_{0} )
c. ( I_{0} )
D. ( frac{I_{0}}{2} )
12
433A very thin film in reflected white light
appears
A . coloured
B. white
c. black
D. red
12
434Ratio of maximum to minimum
ntensities at ( P ) is
( A, 2: 1 )
3.4: 1
( c cdot 8: 1 )
0.16: 1
12
435Find the nature and order of the
interference at 0
( A cdot 20^{t h} operatorname{minimal} )
B. ( 20^{text {th }} ) maxima
( mathrm{c} cdot 10^{t h} ) maxima
( D cdot 10^{t h} operatorname{minimaa} )
12
436For a single slit of width “a”, the first
minimum of the interference pattern of
a monochromatic light of wavelength ( lambda ) occurs at an angle of ( frac{k}{a} . ) At the same angle of ( frac{k}{a}, ) we get a maximum for two narrow slits separated by a distance “a” Explain.
12
437In a Young’s double slit experiment set
up, source ( S ) of wavelength ( 500 n m )
illuminates two slits ( S_{1} ) and ( S_{2} ) which
act as two coherent sources. The source
( S ) oscillates about its own position
according to the equation ( y=0.5 sin pi t )
where ( y ) is in ( mathrm{mm} ) and ( t ) in seconds. The
minimum value of time ( t ) for which the
intensity at point ( P ) on the screen
exactly infront of the upper slit becomes minimum is :
( A cdot 1 s )
B. ( 2 s )
( c .3 s )
D. ( 1.5 s )
12
438Consider the arrangement shown in Fig
29.15(a). The distance ( D ) is large,
compared to ( d ). Find minimum value of
( d ) so that there is a dark fringe at ( O . ) For
the same value of ( d ) find ( x ) at which next
bright fringes is formed.
12
439A beam of unpolarized light is passed first through a tourmaline crystal ( boldsymbol{A} ) and then through another tourmaline
crystal ( B ) oriented so that its principal
plane is parallel to that of ( A ). The
intensity of final emergent light is ( I )
The value of the ( I ) is
A ( cdot frac{I_{o}}{2} )
в. ( frac{I_{o}}{4} )
c. ( frac{I_{o}}{8} )
D. none of these
12
440The speed at which the current travels
in a conductor, is nearly.
A ( .3 times 10^{4} m s^{-1} )
В. ( 3 times 10^{5} mathrm{ms}^{-1} )
c. ( 4 times 10^{6} m s^{-1} )
D. ( 3 times 10^{8} mathrm{ms}^{-1} )
12
441Derive the expression for the intensity at a point where interference of light occurs. Arrive at the conditions for the
maximum and zero intensity.
12
442The first diffraction minima due to a
single slit diffraction is at ( theta=30^{circ} ) for a
light of wavelength 5000 A. The width of the slit is:
( mathbf{A} cdot 5 times 10^{-5} mathrm{cm} )
В. ( 10 times 10^{-5} mathrm{cm} )
c. ( 2.5 times 10^{-5} mathrm{cm} )
D. ( 1.25 times 10^{-5} mathrm{cm} )
12
443In ( Y D S E, d=2 m m, D=2 m ) and ( lambda=500 )
nm. If intensity of two slits are ( l_{0} ) and ( 9 l_{0} )
then find intensity at ( boldsymbol{y}=frac{1}{6} )
A. ( 7 l_{0} )
B. ( 10 l_{0} )
c. ( 16 l_{0} )
D. ( 4 l_{0} )
12
444Light is incident on a polarizer with
intensity ( I_{0} . ) A second prism called
analyser is kept at a angle of ( 15^{circ}, ) from the first polarizer then the intensity of final emergent light will be?
12
445(a) How does an unpolarized light incident on a Polaroid get polarized? Describe briefly, with the help of a necessary diagram, the polarization of light by reflection form a transparent medium.
(b) Two polaroids ( ^{prime} A^{prime} ) and ( ^{prime} B^{prime} ) are kept in crossed position. How should a third
Polaroid ‘ ( C^{prime} ) be placed between them so that the intensity of polarized light transmitted by Polaroid ( B ) reduces to 1/8th of the intensity of unpolarized light incident of ( boldsymbol{A} ) ?
12
446Which of the following does not support the wave nature of light?
A . Interference
B. Diffraction
c. Polarisation
D. Photoelectric effect.
12
447In a Young’s double slit experiment, let
( A ) and ( B ) be the two slits. A thin film of
thickness ( t ) and refractive index ( mu ) is
placed in front of ( boldsymbol{A} ). Let ( boldsymbol{beta}= ) fringe width The central maximum will shift
This question has multiple correct options
A. towards ( A )
B. towards ( B )
( c cdot operatorname{byt}(mu-1) frac{beta}{lambda} )
D. by ( mu t frac{beta}{lambda} )
12
448Does the principle of conservation of energy hold for interference and
diffraction phenomena? Explain briefly.
12
449The path of the difference between two interfering the waves at a point on the screen ( frac{lambda}{8} . ) The ratio of intensity at this point and that of at the central fringe will be
( mathbf{A} cdot 0.853 )
B. 8.53
c. 85.3
D. 853
12
450Consider a two slit interference
arrangements such that the distance of
the screen from the slits is half the
distance between the slits. Obtain the
value of ( mathrm{D} ) in terms of ( lambda ) such that the
first minima on the screen falls at a
distance D from the centre 0
( A cdot frac{lambda}{2.472} )
в. ( frac{lambda}{2.236} )
c. ( frac{lambda}{1.227} )
D. ( frac{lambda}{3412} )
12
45115. Unpolarized light of intensity 32 Wm passes thro
three polarizers such that transmission axes of the first
and second polarizer makes and angle 30° with each other
and the transmission axis of the last polarizer is crossed
with that of the first. The intensity of final emerging light
will be
(a) 32 Wm-2
(b) 3 Wm-2
(c) 8 Wm-2
(d) 4 Wm-2
12
452Two coherent sources ( S_{1} ) and ( S_{2} )
vibrating in phase emit light of wavelength ( lambda ). The separation between them is ( 2 lambda ) as shown in figure. The first bright fringe is formed at ( P ) due to
interference on a screen placed at a
distance ( D ) from ( S_{1}(D>>lambda), ) then ( O P )
is:
A ( cdot sqrt{2} D )
в. ( 1.5 D )
c. ( sqrt{3} D )
D. ( D )
12
453(A) : Newton’s corpuscular theory of light could not explain refraction of light.
(B) : Huygen’s wave theory fails to
explain polarization property of light.
A. A is true B is false
B. A is false B is true
c. Both ( A ) and ( B ) are true
D. Both A and B are false
12
454Destructive interference of two waves
travelling in a medium occurs when the crest of one wave lines up with the
of another wave
A. trough
B. amplitude
c. crest
D. frequency
E. wavelength
12
455How could two waves on a rope interfere
so that the rope did not move at all?
12
456Assertion
In Young’s interference experiment fringes become brighter if one of the slits is covered by cellophone paper.
Reason
The intensity of light emerging from the slit increases and the two interfering
beams have unequal intensities.
A. Statement I is True and Statement 2 is True and is correct explanation of Statement 1
B. Statementl is True and Statement 2 is True but not the correct explanation of Statement t.
c. statement lis False and statement 2 is False
D. Statement lis True and Statement 2 is False
12
457In Young’s experiment, the wavelength
of monochromatic light used is 6000 A. the optical path difference between the rays from the two coherent sources at
point ( P ) on the screen is ( 0.0075 mathrm{mm} ) and at a point ( Q ) on the screen is ( 0.0015 mathrm{mm} ) How many bright and dark bands are observed between the two points ( P ) and
Q?
12
458U 0.034 11
38. In a double-slit experiment, the dista
double-slit experiment, the distance between the slits
is d. The screen is at a distance D from the slits. If a bright
fringe is formed opposite to a slit on the screen, the order
of the fringe is

22D
22D
d2
(d) 0
d
(C) AND
12
459Identify the correct statement from the
following:
A. Wave nature of light was proposed by Huygens.
B. The direction of light ray and its wave front are opposite.
C. Huygen’s wave theory could not explain phenomenon of reflection.
D. A monochromatic ray of light after passing through the prism should create a spectrum of seven colours.
12
460When two waves of almost equal
frequency ( n_{1} ) and ( n_{2} ) are produced simultaneously, then the times interval between successive maxima is
A ( cdot frac{1}{n_{1}+n_{2}} )
в. ( frac{1}{n_{1}}+frac{1}{n_{2}} )
c. ( frac{1}{n_{1}}-frac{1}{n_{2}} )
D. ( frac{1}{n_{1}-n_{2}} )
12
461State any one phenomenon in which moving particles exhibit wave nature.12
46260. A thin film of refractive index 1.5 and thickness
4×10-cm is illuminated by light normal to the surface.
What wavelength within the visible spectrum will be
intensified in the reflected beam?
(a) 4800 Å
(b) 5800 Å
(c) 6000 Å
(d) 6800 Å
12
463In Young’s double slit experiment, first slit has width four times the width of
the second slit. The ratio of the
maximum intensity to the minimum intensity in the interference
fringe system is:
A . 2: 1
B . 4: 1
c. 9: 1
D. 8: 1
12
46420. On a hot summer night, the refractive index of ai
smallest near the ground and increases with height from
the ground. When a light beam is directed horizontally
the Huygen’s principle leads us to conclude that as it
travels, the light beam
(a) becomes narrower
(b) goes horizontally without any deflection
(c) bends downwards
(d) bends upwards
(JEE Main 2015)
12
465Phase difference at the central point changes by ( pi / 3 ) when a thick film having refractive index 1.5 and
thickness ( 0.4 mu m ) is placed in front of
upper slit of a YDSE setup. If the wavelength (in ( n m ) ) of the light used is ( 600 mathrm{k}, ) find ( mathrm{k} )
12
466Which of the following cannot be polarised?
B. ( beta ) rays
c. Infrared rays
D. ( gamma ) rays
12
467For minima to take place between two monochromatic light waves of
wavelength ( lambda ), the path difference
should be
A ( . n lambda )
B. ( (2 n-1) frac{lambda}{4} )
c. ( (2 n-1) frac{lambda}{2} )
D. ( (2 n-1) lambda )
12
4683
incident at an angle ( alpha=30^{circ} ) with the
normal to the slit plane in Young’s double-slit experiment. Assume that
the intensity due to each slit at any
point on the scree is ( I_{0} . ) Point ( O ) is
equidistant from ( S_{1} ) and ( S_{2} ). The
distance between slits is 1 mm. Then
This question has multiple correct options
A. the intensity at ( O ) is ( I_{0} )
B. the intensity at ( O ) is zero
C. the intensity at a point on the screen ( 1 m ) below ( O ) is ( I_{0} )
D. the intensity at a point on the screen ( 1 m ) below ( O ) is
zero
12
469The ratio of maximum to minimum
intensity due to superposition of two waves is ( frac{49}{9} . ) Then the ratio of the
intensity of component waves is
A ( cdot frac{25}{4} )
в. ( frac{16}{25} )
c. ( frac{4}{49} )
D. ( frac{9}{49} )
12
470An astronaut is looking down on earth’s
surface from a space shuttle an altitude of ( 400 mathrm{km} ) Assuming that the astronaut’s pupil diameter is ( 5 mathrm{mm} ) and the wavelength of visible light is ( 500 mathrm{nm}, ) the astronaut will be able to resolve linear objects of the size of
A . ( 0.5 mathrm{m} )
B. 5 m
( c . ) 50m
D. 500m
12
471In the Young’s double slit experiment
two slits 0.125 mm apart are
illuminated by light of wavelength
( 4500 A^{circ} . ) The screen is ( 1 m ) away from
the plane of the slits. Find the separation between second bright fringes on both sides of central maxima.
12
472In Youngs double slit experiment using monochromatic light, the fringe pattern
shifts by a certain distance on the
screen when a mica sheet of ( R . l . ) and
thickness 1.964 micron is introduced in
the path of one of the interfering waves.
The mica sheet is then removed and the
distance between the slits and the
screen is doubled, it is found that the distance between successive maxima
(or minima) now is the same as the
observed fringe shift upon the introduction of the mica sheet.
Calculate the wavelength of monochromatic light used in the experiment.
12
473toppr ‘ОGा
but represents path from each of the
two slits to the third “bright fringe”
formed as part of the interference
pattern.
In the diagram how much longer is path
1 than path ( 2 ? )
( mathbf{A} .400 n m )
B. ( 1200 n m )
( mathbf{c} cdot 1600 n m )
D. ( 1000 n m )
E . ( 600 n m )
12
474The phenomenon of rotation of plane polarized light is called:
A. Kerr effect
B. Double refraction
c. optical activity
D. Dichroism
12
475A light wave is incident normally over a slit of width ( 24 times 10^{-5} mathrm{cm} . ) The angular
position of second dark fringe from the
central maxima is ( 30^{circ} . ) What is
wavelength of light?
в. 5000 月
c. ( 3000 hat{h} )
D. 1500 月
12
476In Young’s double slit experiment, the
ratio of maximum to minimum
intensities of the fringe system is 4: 1 The amplitudes of the coherent sources are in the ratio:
A . 4: 1
B. 3: 1
c. 2: 1
D. 1: 1
12
477If the path difference between the slits
( S_{1} ) and ( S_{2} ) is ( lambda, ) the central fringe will
have an intensity of
A. 0
B . ( a^{2} )
( c cdot 2 a^{2} )
D. ( 4 a^{2} )
12
478What is polarization of light?12
479According to corpuscular theory, the velocity of light in the denser medium is
greater than that in rarer medium.
A. True
B. False
12
480In a Young’s double slit experiment, a
slab of thickness ( 1.2 mu m ) and refractive
index 1.5 is placed in front of one slit
and another slab of thickness t and
refractive index 2.5 is placed in front of
the second slit. If the position of the central fringe remains unaltered, then
the thickness is
A. ( 0.4 mu m )
B. ( 0.8 mu m )
c. ( 1.2 mu m )
D. ( 0.72 mu m )
12
481The shape of wave front at a very large distance from source is
A. Circular
B. Spherical
c. cylindrical
D. Plane
12
48243. A plane wavefront (a = 6x 10-7m) falls on a slit 0.4 mm
wide. A convex lens of focal length 0.8 m placed behind
the slit focusses the light on a screen. What is the linear
diameter of second maximum?
(a) 6 mm
(b) 12 mm
(c) 3 mm
(d) 9 mm
12
483Determine the distance of 4 th dark
fringe from the left end of air cavity
A ( cdot frac{2 L}{6}+lambda_{0} )
B. ( _{L_{1}+} frac{3 L}{4} )
( c cdot frac{4 L}{7} )
D. ( frac{5 L}{7} )
12
484Distance of ( 5^{t h} ) dark fringe from centres
is 4 mm. If ( D=2 m, lambda=600 n m, ) then
distance between slits is
A. ( 1.35 mathrm{mm} )
B . ( 2.00 mathrm{mm} )
c. ( 3.25 mathrm{mm} )
D. ( 10.35 mathrm{mm} )
12
485In a Young’s double slit experiment, let
( beta ) is the fringe width, and let ( I_{o} ) be the intensity at the central bright fringe. At a distance ( x ) from the central bright
fringe, the intensity will be:
A ( cdot I_{o} cos left(frac{x}{beta}right) )
B ( cdot I_{o} cos ^{2}left(frac{x}{beta}right) )
( mathbf{c} cdot_{I_{o} cos ^{2}left(frac{pi x}{beta}right)} )
D. ( left(frac{I_{o}}{4}right) cos ^{2}left(frac{pi x}{beta}right) )
12
486Two beams, ( A ) and ( B ), of plane polarized light with mutually perpendicular planes of polarization are seen through a polaroid. From the position when the beam A has maximum intensity (and beam B has zero intensity), a rotation of
Polaroid through ( 30^{circ} ) makes the two
beams appear equally bright. If the initial intensities of the two beams are
( boldsymbol{I}_{A} ) and ( boldsymbol{I}_{B} ) respectively, then ( boldsymbol{I}_{boldsymbol{A}} / boldsymbol{I}_{boldsymbol{B}} )
equals:
A . ( I )
B. ( I / 3 )
( c cdot 3 )
D. ( 3 / 2 )
12
487Write any two applications of interference12
488The distance between two consecutive
bright bands in a bi-prism experiment is ( 0.32 mathrm{mm} ) When the red light of wavelength 6400 A is used. by how much will this distance change if the light is substituted by the blue light of wavelength 4800 A with the same
setting?
12
489A wave is associated with matter when
it is:
A. stationary
B. in motion with a velocity
C. in motion with velocity of light
D. in motion with velocity greater than that of light
12
490A broad source of light ( (1=680 mathrm{nm}) ) illuminates normally two glass plates ( 120 mathrm{mm} ) long that touch at end and are separated by a wire ( 0.048 mathrm{mm} ) in diameter at the other end. The total
number of bright fringes that appear over the ( 120 mathrm{mm} ) distance is:
A . 50
B. 100
( c cdot 141 )
D. 400
12
491State two conditions for sustained
interference of light. Also write the
expression for the fringe width
12
492Light of wavelength 500 nm goes through a pinhole of ( 0.2 m m ) and falls on
a wall at a distance of ( 2 m ). What is the
radius of the central bright spot formed
on the wall?
A ( .2 .37 mathrm{cm} )
в. 1.37 ст
( c .3 .37 mathrm{cm} )
D. ( 7.37 mathrm{cm} )
12
493When light falls on matter, it can produce :
A. mechanical effect
B. chemical effect
c. heating effect
D. all the above
12
494Derive an expression for the bandwidth
of interference fringes in Young’s double slit experiment.
12
495The diameter of an objective of a telescope, which can just resolve two stars situated at an angular
displacement of ( 10^{-4} ) degree, should be
( left(lambda=5000 A^{0}right) )
A. 35 mm
B. 35 cm
( c cdot 35 m )
D. None of the above
12
496In the adjacent, ( C P ) represents a
wavefront and ( A O & B P, ) the
corresponding two rays. Find the
condition on ( theta ) for constructive
interference at ( boldsymbol{P} ) between the ray ( boldsymbol{B P} )
and reflected ray ( boldsymbol{O P} )
( A cdot cos theta=3 lambda / 2 d )
B. ( cos theta=lambda / 4 d )
( mathbf{c} cdot sec theta-cos theta=lambda d )
( mathbf{D} cdot sec theta-cos theta=4 lambda d )
12
497Choose the correct option about light.
A. Light requires a material medium to travel from one place to another
B. Light does not require a material medium to propagate
c. Light has mass but it is negligible
D. Light waves are longitudinal wave
12
498Two sound speakers are driven in phase by an audio amplifier at frequency ( 600 H z . ) The speed of sound is ( 340 m / s )
The speakers are on the ( y ) -axis, one at ( boldsymbol{y}=+1.0 boldsymbol{m} ) and the other at ( boldsymbol{y}= )
( -1.0 m . ) A listener begins at ( y=0 ) and
walks along a line parallel to the ( y ) -axis at a very large distance ( x ) away. At what
angle ( theta^{o} ) (between the line from the origin to the listener at the ( x ) -axis will
she first hear a minimum sound
intensity?
12
499An unpolarized beam of intensity ( 2 a^{2} ) passes through a thin Polaroid. Assuming zero absorption in the Polaroid, the intensity of emergent planes polarized light will be
( mathbf{A} cdot 2 a^{2} )
в. ( a^{2} )
( c cdot sqrt{2} a )
D. ( frac{a^{2}}{sqrt{2}} )
12
500In Young’s double slit experiment, the fringe width is ( beta . ) If the entire
arrangement is placed in a liquid of refractive index ( mu, ) the fringe width will become
A. ( mu beta )
в. ( frac{beta}{mu} )
( c cdot frac{beta}{mu+1} )
D. ( frac{beta}{mu-1} )
12
501Law of conservation of energy is
satisfied because
A. equal loss and gain in intensity is observed
B. all bright fringes are equally bright
C. all dark fringes are of zero brightness
D. the average intensity on screen is equal to the sum of intensities of the two sources.
12
502A long horizontal slit is place 1 mm above a horizontal plane mirror. The interference between the light coming directly from the slit and that after reflection is seen on a screen 1 m away
from the slit. If the mirror reflects only
( 64 % ) of the light falling on it, the ratio of
the maximum to the minimum
intensity in the interference pattern
observed on the screen is:
( mathbf{A} cdot 8: 1 )
B . 3: 1
c. 81: 1
D. 9: 1
12
50373. Figure shows two coherent sources S, and S, emittin
wavelength 2. The separation S, S2 = 1.52 and S, is ahe
in phase by Td/2 relative to S2. Then the maxima occur in
direction given by sin of
(i) O (ii) 1/2
(iii) -176 (iv) -5/6 si
Correct options are
(a) (ii), (iii), and (iv) S.
(b) (i), (ii), and (iii)
(c) (i), (iii), and (iv)
(d) All the above
12
504A beam of unpolarized light is passed
first through a tourmaline crystal ( boldsymbol{A} ) and
then through another tourmaline
crystal ( B ) oriented so that its principal
plane is parallel to that of ( A ). The
intensity of final emergent light is ( I ). If
( A ) is rotated by ( 45^{0} ) on a plane,
perpendicular to the direction of incident ray, then intensity of emergent light will be
A ( cdot frac{I}{8} )
в. ( frac{I}{4} )
c. ( frac{I}{2} )
D. none of these
12
505Mark the CORRECT statements(s)
This question has multiple correct options
A. Direction of wave propagation is along the normal to wavefront.
B. For a point source of light, the shape of wavefront can be considered to be plane at very large
distance from the source.
C. A point source of light is placed at the focus of a thin spherical lens, then the shape of the wavefront for emerged light may be plane.
D. The shape of the wavefront for the light incident on a thin spherical lens (kept in vacuum) is plane, the shape of the wavefront corresponding to emergent light would be always spherical
12
506In case of theory of light nature of light
match the following:
List – I List – II
a) Light is a collection of
e) Newton’s theory photons
b) Light is a form of
f) Huygen’s theory electromagnetic wave
g) Maxwell’s
c) Light is a wave
d) Light is a stream of
h) Max planck’s corpuscles theory
( mathbf{A} cdot mathrm{a}-mathrm{h} ; mathrm{b}-mathrm{g} ; mathrm{c}-mathrm{f} ; mathrm{d}-mathrm{e} )
B. ( a-e ; b-f ; c-g ; d-h )
C. ( a-g ; b-h ; c-g ; d-f )
D. ( a-h ; b-g ; c-e ; d-f )
12
507In Young’s double-slit experiment, 12 fringes are observed to be formed in a certain segment of the screen when light of wavelength 600 nm is used. If the wavelength of light is changed to ( 400 n m, ) number of fringes observed in the same segment of the screen is given by
A . 12
B . 18
( c cdot 24 )
D. 30
12
508The class of diffraction in which the
incident and diffracted wave fronts are
spherical is called
A. Fraunhofer diffraction
B. Fresnel diffraction
c. Huygens’ diffraction
D. Newton’s diffraction
12
509A source of electrons or neutrons can be
located at ( S ). The beam is defined by
slits ( S_{1} ) and ( S_{2} . ) The particles pass
through two plates ( P_{1} ) and ( P_{2} ) such that
the first plate is at zero potential and
the second plate can be given any high potential. For using matter waves in a microscope of high resolution which of
the following combination must be chosen?
A. Electron beam with high accelerating potential
B. Electron beam with low accelerating potential
c. Neutron beam with high accelerating potential
D. Neutron beam with low accelerating potential
12
510Assertion
In YDSE, if a film is introduced in front
of the upper slit, then the fringe pattern shifts in the downward direction
Reason
In YDSE if the slit widths are unequal,
the minima will be completely dark
A. Both Assertion and Reason are incorrect
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
c. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are correct
12
511A CD(Compact disc ) is read from the bottom by a semiconductor laser with wavelength ( 700 n m ) passes through a
plastic substrate of refractive index 1.8
When the beam encounters 0 pit, part of the beam is reflected from the pit and part from the flat region. These two beams interfere with each other. What
must be the minimum depth of the pit, So that part of the beam reflected from the pit and part reflected from the flat surface cancel out? (This cancellation
allows the player to recognize beginning and end of a pit)
A. ( 0.197 mu m )
B. ( 0.395 mu m )
( c .0 .22 mu m )
D. ( 0.11 mu ) m
12
512A circular beam of light of diameter
( d=2 c m ) falls on a plane surface of
glass. The angle of incident is ( 60^{circ} ) and refractive index of glass is ( mu=3 / 2 . ) The
diameter of the refracted beam is
A ( .2 .00 mathrm{cm} )
в. ( 1.50 mathrm{cm} )
c. ( 1.63 mathrm{cm} )
D. ( 2.52 mathrm{cm} )
12
513A plane wavefront of wavelength ( lambda ) is incident on a single slit of width a. The
angular width of principal maximum
is?
( A cdot frac{lambda}{a} )
в. ( frac{2 lambda}{a} )
( c cdot frac{a}{lambda} )
D. ( frac{a}{2 lambda} )
12
514When a compact disc is illuminated by small source of white light, coloured bands are observed. This is due to
A. dispersion
B. diffraction
c. interference
D. reflection
12
515Find the nature and order of the
interference at the point ( P )
A ( cdot 70^{t h} ) maxima
B. ( 80^{text {th }} ) minima
( mathbf{c} cdot 60^{t h} operatorname{maxima} )
( D cdot 70^{t h} operatorname{minima} )
12
516In Young’s double slit experiment, the interference pattern obtained with white light will be
A. the central fringe bright and alternate bright and dark fringes
B. the central fringe achromatic and coloured fringes for small path difference
c. the central fringe dark
D. the central fringe coloured
12
517Two slits in Young’s experiment have widths in the ratio ( 1: 25 . ) The ratio of
intensity at the maxima and minima in the interference pattern, ( frac{boldsymbol{I}_{max }}{boldsymbol{I}_{min }} ) is
A ( cdot frac{4}{9} )
B. ( frac{9}{4} )
c. ( frac{121}{49} )
D. ( frac{49}{121} )
12
518Two cohorent monochromatic light beams of intensities ( 4 mid ) and 9 I interfere
in a Young’s double slit experimental setup to produce a fringe pattern on the screen. The phase difference between
the beams at two points ( P ) and ( Q ) on the
screen are ( pi / 2 ) and ( pi / 3 ) respectively.
Then the ratio of the two intensities
( boldsymbol{I}_{boldsymbol{P}} / boldsymbol{I}_{Q} ) is
A. 0
в. ( frac{6}{19} )
c. ( frac{13}{19} )
D. ( frac{6}{13} )
12
519A narrow tube is bent in the form of a
circle of radius ( R, ) as shown in the
figure. Two small holes ( S ) and ( D ) are made in the tube at the positions right angle to each other. A source placed at S generated a wave of intensity ( l_{0} ) which
is equally divided into two parts : One part travels along the longer path, while the other travels along the shorter path. Both the part waves meet at the point ( D ) where a detector is placed. The maximum value of ( lambda ) to produce a
maxima at D is given by :
A ( . pi R )
В. ( 2 pi R )
c. ( frac{pi R}{2} )
D. ( frac{3 pi R}{2} )
12
520Light travels in a ( _{-}-_{-}-_{-}-_{-}- ) path
A . rectilinear
B. zig zagg
c. circular
D. helical
12
521A very thin film in reflected white light
appears
A . coloured
B. white
c. black
D. red
12
522toppr
does this affect the size and intensity of
the central diffraction band?
(b) In what way is diffraction from each
slit related to the interference pattern in a double-slit experiment?
(c) When a tiny circular obstacle is placed in the path of light from a distant source, a bright spot is seen at the centre of the shadow of the obstacle.
Explain why?
(d) Two students are separated by a ( 7 mathrm{m} ) partition wall in a room ( 10 mathrm{m} ) high. If both light and sound waves can bend
around obstacles, how is it that the
students are unable to see each other
even though they can converse easily.
(e) Ray optics is based on the assumption that light travels in a straight line. Diffraction effects (observed when light propagates through small apertures/slits or around small obstacles) disprove this assumption. Yet the ray optics assumption is so commonly used in understanding location and several other properties of images in optical instruments. What is the justification?
12
523What is wavefront? Explain laws of refraction of light on the bases of
Huygens wave theory.
12
524Human eye:
A. can detect polarized light
B. cannot detect polarization of light
C. can detect only circularly polarized light
D. can detect only linearly polarized light
12
525A: Coloured spectrum is seen when we look through a cloth
R: Diffraction of light takes place when light is travelling through the pores of cloth
A. Both A and R are true, and R is not correct explanation of A
B. Both A and R are true, and R is correct explanation of A
C. A is true but R is false
D. A is false but R is true
12
526Which of the following phenomena can be used to analyse a beam of light into its component wavelength?
A . Reflection
B. Refraction
c. Polarisation
D. Interference
12
5273. In Young’s double slit
experiment, the intensity on the screen at a point where
path difference is 2 is K. What will be the intensity at the
point where path difference is N14?
K
K
(a)
7
(b) 5
(c) K
(d) Zero
12
528n identical waves each of intensity ( 1_{0} ) interfere with each other. The ratio of
maximum intensities if the
interference is (i) coherent and (ii) incoherent is:
( mathbf{A} cdot n^{2} )
B.
c. ( frac{1}{n^{2}} )
D.
12
529(a) Define wave-front. Use Huygen’s
principle to verify the laws of refraction.
(b) How is linearly polarised light obtained by the process of scattering of light? Find the Brewster angle for airglass interface, when the refractive
index of glass ( =1.5 )
12
530Two waves are travelling and
superimposed as a result of this
constructive interference occur
between waves, the two waves
amplitude are:
A. added to produce a larger amplitude
B. subtracted to produce a smaller amplitude.
C . added to produce a smaller amplitude.
D. cancelled out by each other
E. in opposite directions.
12
531Sound waves from a tuning fork A reach a point ( P ) by two separate paths ABP and ACP.When ACP is greater than ABP by ( 11.5 mathrm{cm}, ) there is silence at P. When the difference is ( 23 mathrm{cm} ) the sound becomes
loudest at ( P ) and when ( 34.5 mathrm{cm} ) there is
silence again and so on. Calculate the minimum frequency (in Hz) of the fork if the velocity of sound is taken to be 331.2 ( mathrm{m} / mathrm{s} )
12
532The maximum number of possible interference maxima for slit separation equal to twice the wavelength in Young’s double slit experiment is :
A . infinite
B. five
c. three
D. zero
12
533Who proposed the wave theory of light?12
534According to Huygens principle, during refraction of light from air to a denser medium
A. Wavelength and speed increase
B. Wavelength decreases but speed increases
c. wavelength and speed decrease
D. Wavelength increases but speed decreases
12
535Explain Malus law for polaroids.12
536A horizontal beam of vertically polarized light of intensity ( 43 mathrm{w} / mathrm{m}^{2} ) is sent
through two polarizing sheets. The
polarizing direction of the first is ( 60^{0} ) to the vertical, and that of the second is
horizontal. The intensity of the light transmitted by the pair of sheets is (nearly)
A. ( 8.1 mathrm{W} / mathrm{m}^{2} )
B. 7.3 ( mathrm{W} / mathrm{m}^{2} )
c. ( 6.4 mathrm{w} / mathrm{m}^{2} )
D. 3.8 ( mathrm{W} / mathrm{m}^{2} )
12
537State Brewster’s Law.
The polarising angle of a transparent medium is ( 60^{circ} . ) Find the refractive index
and the angle of refraction ( left(tan 60^{circ}=right. ) ( sqrt{3}) )
12
538Two nearby objects are just resolved, if the principle maximum in the diffraction pattern of one coincides with
A. principal maxima of other
B. first minimum of the other
c. half-way between principal maximum and first ( operatorname{minimum} )
D. second maximum of the other
12
539What are Fraunhofer lines??12
540Optically active substances are those
which
A. produce polarized light
B. rotate the plane of polarization of the polarized light.
c. produce double refraction
D. convert a plane polarized light into circularly polarized light
12
541Light of wavelength 589.3 nm is incident normally on a slit of width ( 0 . ) ( mathrm{mm} . ) The angular width of the central diffraction maximum at a distance of
Im from the slit is
A ( cdot 0.68 )
В. ( 0.34^{circ} )
( c .2 .05 )
D. None of these
12
542The intensity at the central maximum
(0) in a Yong’s double slit experimental
set-up shown in the figure is ( I_{O} ). If the
distance ( O P ) equals one-third of the
fringe width of the pattern. show that
the intensity at point P.would equal ( frac{I_{O}}{4} )
12
543Two coherent sources of equal
intensities produce a maximum of 100 units. If the amplitude of one of the
sources is reduced by ( 20 % ), then the maximum intensity produced will be:
A . 100
B. 81
c. 89
D. 60
12
54421. Assuming human pupil to have a radius of 0.25 cm and
a comfortable viewing distance of 25 cm, the minimum
separation between two objects that human eye can
resolve at 500 nm wavelength is
(a) 1 um
(b) 30 um
(c) 100 um
(d) 300 um (JEE Main 2015)
1
12
545Which of the following is the path difference for destructive interference?
A. ( n(lambda+1) )
B. ( (2 n+1) frac{lambda}{2} )
c. ( n lambda )
D. ( (n+1) frac{lambda}{2} )
12
546The polarising angle for a medium is
found to be ( 60^{circ} . ) The critical angle of the medium is
A ( cdot sin ^{-1}left(frac{1}{2}right) )
B. ( sin ^{-1}left(frac{sqrt{3}}{2}right) )
( ^{c} cdot sin ^{-1}left(frac{1}{sqrt{3}}right) )
D. ( sin ^{-1}left(frac{1}{4}right) )
E ( cdot sin ^{-1}left(frac{2}{sqrt{3}}right) )
12
547A: The corpuscular theory fails in explaining the velocities of light in air and water.
B: According to corpuscular theory, the light should travel faster in a ‘denser medium than in a rarer medium.
A. If both A and B are true but the B is the correct explanation of A
B. If both A and B are true but the B is not the correct explanation of A
c. If A is true but B is false
D. If both the A and B are false
E. If B is true but A is false
12
548If the source of light used in a Young’s double slit experiment is changed from red to violet
A. the fringes will become brighter
B. consecutive fringes will come closer
c. the intensity of minima will increase
D. the central bright fringe will become a dark fringe
12
549Two loudspeakers are emitting sound
waves of wavelength ( mu ) with an initial
phase difference of ( frac{pi}{2} . ) At what minimum distance from 0 on line AB
will one hear a maxima?
A ( .25 lambda )
B. ( frac{100 lambda}{sqrt{15}} )
( c cdot frac{25 lambda}{3} )
D. ( 50 lambda )
12
550The condition for observing Fraunhoffer diffraction from a single slit is that the light wavefront incident on the slit
should be
A. spherical
B. cylindrical
c. plane
D. elliptical
12
551The velocity of central maxima at ( t=5 s )
( mathbf{i} mathbf{S} )
A ( .50 m s^{-1} ) along Y-axis
B. ( 50 m s^{-1} ) along negative Y-axis
( mathrm{c} cdot 3 times 10^{8} mathrm{m} mathrm{s}^{-1} ) along ( mathrm{Y} ) -axis
D. ( 3 times 10^{8} mathrm{m} mathrm{s}^{-1} ) along negative Y-axis
12
552De Broglie theorized that all moving objects emit waves (matter waves) based on their momentum ( left(frac{boldsymbol{h}}{boldsymbol{m v}}right) ) Accordingly, as your team’s defensive end, it is your job to stop the other team’s 250 pound fullback. If you could hear the fullback’s matter waves and
you listened as the opposing fullback
toward you, what sound would you hear?
A. An increase in loudness and an increase in frequency
B. An increase in loudness and a decrease in frequency
c. A decreasing loudness and an increasing frequency
D. A decreasing loudness and a decreasing frequency
E. Just a loud thump! thump! thump!
12
553Fresnel diffraction is produced due to light rays falling on a small obstacle.
The intensity of light at a point on a screen beyond an obstacle depends on:
A. the focal length of lens used for observation
B. the number of half-period zones that superpose at the point
c. the square of the sum of the number of half period zones
D. the thickness of the obstacle
12
554The ratio of slit widths in Young’s double
slit experiment is ( 4: 9 . ) The ratio of
maximum and minimum intensities
will be
A. 169: 25
B. 81: 16
c. 13: 5
D. 25: 1
12
555In Young’s interference experiment, the central bright fringe can be identified
due to the fact that it
A. has greater intensity than other fringes which are bright
B. is wider than the other bright fringes
c. is narrower than the other bright fringes
D. can be obtained by using white light instead of monochromatic light
12
556toppr
B.
( mathbf{C} )
( D )
12
557A: Fresnel diffraction occurs when the
source of light or the screen or both are at a finite distance from the diffracting
device
B: Diffracted light can be used to estimate the helical structure of nuclic
acids
A. A is true, B is false
B. Both A and B are true
c. A is false, B is true
D. Both A and B are false
12
558An unpolarized beam of light is incidents on a group of four polarizing sheets, which are arranged in such a way, that of the characteristic direction
of each polarizing sheet makes an
angle of ( 30^{0} ) with that of the preceding
sheet. The percentage of incident light transmitted by the first polarizered will be :
( mathbf{A} cdot 100 % )
B. ( 50 % )
c. ( 25 % )
D. ( 12.5 % )
12
559A beam of unpolarised light passes through a tourmaline crystal ( A ) and
then through another such crystal ( B )
oriented so that the principal plane is
parallel to ( A ). The intensity of emergent
light is ( I . ) If ( A ) now rotated by ( 45^{circ} ) in a
plane perpendicular to direction of the incident ray. The emergent light will have intensity.
A ( cdot frac{I}{2} )
B. ( frac{I}{sqrt{2}} )
c. ( I )
D. ( frac{I}{4} )
12
560State Brewster’s law.
Find Brewster’s angle for a transparent liquid having refractive index 1.5
12
5615. The angle of incidence at which reflected light is totally
polarized for reflection from air to glass (refraction index
n) is
(a) sin(n)
(b) sin
(c) tan-
(d) tan-‘(n)
(AIEEE 2004)
12
562Light waves exhibit polarization but sound waves do not exhibit polarization because they are not:
A. longitudinal
B. coherent
c. dispersive
D. transverse
E. refractive
12
563Initially interference is observed with the entire experimental set up inside a chamber filled with air, Now the
chamber is evacuated. With the same
source of light used, a careful observer
will find that.
A. The interference pattern is almost absent as it is very much diffused
B. There is no change in the interference pattern
c. The fringe width is slightly decreased
D. The fringe width is slightly increased
12
564A soap film of thickness ( t ) is surrounded
by air and is illuminated at near normal
incidence by monochromatic light with wavelength ( lambda ) in the film. With respect
to the wavelength of the monochromatic light in the film, what film thickness will produce maximum constructive interference?
A ( cdot frac{1}{4} lambda )
B. ( frac{1}{2} lambda )
c. ( 1 lambda )
D. ( 2 lambda )
12
565A thin film with index of refraction 1.33
coats a glass lens with index of
refraction ( 1.50 . ) Which of the following
choices is the smallest film thickness
that will not reflect light with
wavelength ( 640 n m ? )
A . ( 160 n m )
B. ( 240 n m )
( c .360 n m )
D. ( 480 n m )
12
566A slit of width a is illuminated by white light. The first minimum for red light ( (lambda=6500 A) ) will fall at ( theta=30 ) when
a will be:
A ( cdot 3200 )
В. ( 6.5 times 10^{-4} mathrm{mm} )
c. 1.3 micron
D. ( 2.6 times 10^{-4} mathrm{cm} )
12
567In the Young’s double slit experiment two light beams of wavelengths ( lambda= )
( 6000 A^{circ} ) and ( lambda=4800 A^{circ} ) are used. The
distance between two slits is ( 2.5 m m )
The distance between slits and the
screen is ( 1.5 m . ) The distance between
the central maxima obtained with two
beams will be
A . zero
B. ( 1.872 m m )
c. ( 2.872 m m )
D. ( 2.652 m m )
12
568The shape of the interference fringes, on
the screen is
A . circle
B. ellipse
c. parabola
D. straight line
12
569After reflection from a concave mirror, a plane wavefront becomes
A. Cylindrical
B. Spherical
c. Remains planar
D. None of the above
12
570Critical angle for certain medium is
( sin ^{-1}(0.6) . ) The polarizing angle of that
medium is :
A ( cdot tan ^{-1}(1.5) )
В ( cdot tan ^{-1}(0.8) )
c. ( tan ^{-1}(1.6667) )
D. ( tan ^{-1}(0.667) )
12
571In double slit experiment, fringes are obtained using light of wavelength
( 4800 A^{circ} . ) One slit is covered with a thin
glass film of refractive index 1.4 and
another slit is covered by a film of same thickness but refractive index ( 1.7 . ) By
doing so, the central fringe is shifted to fifth bright fringe in the original pattern The thickness of glass film is :
A ( cdot 2 times 10^{-3} m m )
B. ( 4 times 10^{-3} mathrm{mm} )
c. ( 6 times 10^{-3} m m )
D. ( 8 times 10^{-3} mathrm{mm} )
12
572Light is a form of that we
can detect with our
A. energy, ears
B. corpuscles, eyes
c. energy, eyes
D. sensation, skin
12
573To increase the magnification of a
telescope
A. the objective lens should be of large focal length and eyepiece should be of small focal length.
B. the objective and eyepiece both should be of large focal length.
C. both the objective and eyepiece should be of smaller focal lengths
D. the objective should be of small focal length and eyepiece should be of large focal length
12
574A beam of unpolarised light having flux ( 10^{-3} ) watt falls normally on a polarizer
of cross sectional area ( 3 times 10^{-4} m^{2} )
The polarizer rotates with an angular frequency of 31.4 rad/s. The energy of light passing through the polarizer per revolution will be:
( mathbf{A} cdot 10^{-4} ) joule
B . ( 10^{-3} ) joule
C ( cdot 10^{-2} ) joule
D. ( 10^{-1} ) joule
12
575State Huygen’s principle.12
576In YDSE, a white light is formed fringe pattern on the screen. Calculate the path difference of the light waves from the two slits at the center of the first
bright fringe above the central maximum.
A. 0
в. ( frac{1}{4} lambda )
( c cdot frac{1}{2} lambda )
D. ( lambda )
E ( cdot frac{3}{2} lambda )
12
577A double slit interference experiment is set up in a chamber that can be
completely evacuated with monochromatic light, an interference pattern is observed when the container
is open to the air. As the container is
evacuated, a careful observer will not that the interference fringes
A. don’t change at all
B. move slightly farther apart
C. move slightly closer together
D. disappear completely
12
578The Young’s double slit experiment is
done in a medium of refractive index
4/3. A light of 600 nm wavelength is falling on the slits have ( 0.45 mathrm{mm} )
separation. The lower slit ( S_{2} ) is covered
by a thin glass sheet of thickness 10.4
mm and refractive index 1.5. The
interference pattern is observed on a
screen placed at ( 1.5 mathrm{m} ) from the slits as
shown in the fig.
(All wavelength in this problem are for
the given medium of refractive index
4/3. Ignore dispersion.) Find the location
of central maxima (bring fringe with
zero path difference ) on the y-axis.
12
579Who first proposed that light was wavelike in character?
A. Huygens
B. Newton
c. Young
D. Maxwell
12
580Let ( S_{1} ) and ( S_{2} ) be the two slits in Young’s double-slit experiment. If central maxima is observed at ( boldsymbol{P} ) and angle
( angle S_{1} P S_{2}=theta, ) then the fringe width for
the light of wavelength ( lambda ) will be
(assume ( theta ) to be a small angle)
( A cdot lambda / theta )
в. ( lambda theta )
c. ( 2 lambda / theta )
D. ( lambda / 2 theta )
12
581Light of wavelength 520 mm passing
through a double slit, produces
interference pattern of relative intensity
versus angular position ( theta ) as shown in the figure. Find the separation
between the slits.
12
582A wave or a pulse is reflected normally from the surface of a denser medium
back into the rarer medium. The phase change caused by the reflection-
A .
B . ( pi / 2 )
( c )
D. ( 3 pi / 2 )
12
583A sound wave of wavelength ( 32 mathrm{cm} ) enters the tube as shown in the figure.
Then the smallest radius ( r ) so that a
maximum of sound is heard at
detector is :
( A cdot 7 mathrm{cm} )
в. 14 ст
( c cdot 21 c m )
D. 28 ст
12
584A transparent medium of the angle of
polarisation is ( 60^{circ} . ) Find the angle of
refraction.
12
585If the source is now changed to green light of wavelength ( 10^{-7} m ) and a new glass plate is placed in place of the previous glass plate, the central fringe shifts to a position initially occupied by the sixth bright fringe due to red light without the glass plate. What is refractive index of new glass plate?
A ( .2 .6 mu m )
в. ( 1.6 mu m )
c. ( 1.2 mu m )
D. ( 2.2 mu m )
12
586Interference is produced with two coherent sources of the same intensity If one of the sources is covered with a
thin film so as to reduce the intensity of light coming out of it to half, then:
A. bright fringes will be less bright and dark fringes will be less dark
B. bright fringes will be more bright and the dark fringes will be more dark
c. brightness of both types of the fringes will remain the same
D. dark region will spread completely
12
587Photoelectric effect supports the
quantum nature of light because
This question has multiple correct options
A. There is minimum frequency of light below which no photoelectrons are emitted
B. The maximum KE of photoelectrons depends only on the frequency of light and not on its intensity
C. Even when the metal surface is faintly illuminated by light of wavelength less than the threshold wavelength, the photoelectrons leave the surface immediately
D. Electric charge of photoelectrons is quantized
12
588Assertion: A white source of light during interference forms only white and black
fringes. Reason: Width of fringe is inversely proportional to the wavelength of the light used.
A. If both assertion and reason are true but the reason is the correct explanation of assertion
B. If both assertion and reason are true but the reason is not the correct explanation of assertion
c. If assertion is true but reason is false
D. If both the assertion and reason are false
E. If reason is true but assertion is false
12
589In YDSE, the source is placed symmetrical to the slits. If a transparent slab is placed in front of the upper slit, then(slab can absorb a
fraction of light)

This question has multiple correct options
A. intensity of central maxima will not change
B. intensity of central maxima may change
c. central maxima will be shifted up
D. intensity of dark fringes will be always zero

12
590Draw and explain the process of
formation of image with a pinhole
camera?
12
591Consider a film of thickness ( L ) as shown
in four different cases below. Notice the
observation of film with perpendicularly falling light. Mark the correct statement(s). (Take ( L=1.5 lambda) )
This question has multiple correct options
A. For (1) and (2), the reflection at film interfaces causes zero phase difference for two reflected rays
B. For 92 ) and (3), the reflection at film interfaces causes phase difference of ( pi ) for two reflected rays
C. For (1) , the film will appear dark, if it is observed through reflected rays from film interfaces
D. For
(3), the film will appear dark, if it is observed through reflected rays from film interfaces
12
592Diffraction gratings provide much brighter interference pattern since more light passes through them compared with double slits.
A . True
B. False
12
593The intensity of principal maxima in the
single slit diffraction pattern is ( I_{o} ) ?
What will be the intensity when slit width is doubled?
A ( .2 I_{0} )
в. ( 4 I_{0} )
c. ( I_{o} )
D. ( frac{I_{0}}{2} )
12
59440. A slit of width a is illuminated by white light. For
red light (a = 6500 Å), the first minima is obtained at
O=30°. Then the value of a will be
(a) 3250 Å
(b) 6.5 x 10-4 mm
(c) 1.24 microns (d) 2.6 x 104 cm
12
595The sensor is exposed for ( 0.1 s ) to a
( 200 W ) lamp ( 10 m ) away. The sensor has opening that is 20 mm in a diameter
How many photons enter the sensor if the wavelength of light is 600 mm? (assume that all the energy of the lamp is given off as light).
A . ( 1.53 times 10^{11} )
B. ( 1.53 times 10^{2} )
c. ( 1.53 times 10^{4} )
D. ( 1.53 times 10^{13} )
12
596At ( t=0, ) fringe width is ( beta_{1}, ) and ( a t t= )
( 2 s, ) fringe width of figure is ( beta_{2} . ) Then
( A cdot beta_{1}>beta_{2} )
в. ( beta_{2}>beta_{1} )
c. ( beta_{1}=beta_{2} )
D. data is insufficient
12
597Which of the following is a unit for intensity of light?
A. candle power
B. Lux
c. Both A & B
D. None of the above
12
maximum, in the diffraction pattern, does not depend on
A. the distance between the slit and sources
B. width of slitt
c. wavelength of light
D. frequency of light
12
599If ( z=frac{lambda D}{4 d} )
A ( cdot[3-2 sqrt{2}]^{2} )
B ( cdot[3+sqrt{2}]^{2} )
c. ( [3-sqrt{2}]^{2} )
D ( cdot[3+2 sqrt{2}]^{2} )
12
600Ekectron microscope is based on the principle
A. Photoelectric effect
B. Wave nature of electron
c. superconductivity
D. Laws of electromagnetic induction
12
601In Lloyd’s single mirror method we have
A. Both sources virtual
B. One source virtual and one real
c. Both sources real
D. None of these
12
60225. Unpolarized light of intensity I passes through an ideal
polarizer A. Another identical polarizer B is placed
behind A. The intensity of light beyond B is found to be
1/2. Now another identical polarizer C is placed between
A and B. The intensity beyond B is now found to be I/8.
The angle between polarizer A and C is
(a) 60°
(b) 0°
(c) 30°
(d) 45°
(JEE Main 2018)
12
60316. In a YDSE with identical slits, the intensity of the central
bright fringe is 1o. If one of the slits is covered, the intensity
at the same point is
(a) 21.
(b) lo
(C) 1/2
(d) 10/4
12
604The path difference between two monochromatic light waves of wavelength ( 4000 A ) is ( 2 times 10^{-7} m . ) The
phase difference between them is
A . ( pi )
B. ( 2 pi )
c. ( frac{3 pi}{2} )
D.
12
605The shape of the wave diverging from a point of source is12
606In Young’s double slit experiment, when
wavelength used is ( 6000 A ) and the
screen is ( 40 mathrm{cm} ) from the slits, the
fringes ( 0.012 mathrm{cm} ) wide. What is the distance between the slits?
A ( .0 .24 mathrm{cm} )
B. ( 0.2 mathrm{cm} )
( mathrm{c} cdot 2.4 mathrm{cm} )
D. ( 0.024 mathrm{cm} )
12
607Electrons accelerated from rest by an electrostatic potential are collimated and sent through a Young’s double slit setup. The figure width is w. If the accelerating potential is doubled then the width is now close to.
( mathbf{A} cdot 0.5 mathrm{w} )
в. 0.7 w
c. ( 1.0 mathrm{w} )
D. 2.0 w
12
608What does the term point to correspondence in the paragraph refer
to?
A. Waves having constant amplitude
B. Waves having constant phase relation
c. Waves having same frequency
D. Wave having same amplitude,frequency and constant phase relation
12
609A: Radio wave can diffract at the edges
of buildings
B: X-rays can diffract at the interiors of a crystal
A. A is true, B is false
B. Both A and B are true
c. A is false, B is true
D. Both A and B are false
12
61057. Blue light of wavelength 480 nm is most strongly reflected
off a thin film of oil on a glass slab when viewed near
normal incidence. Assuming that the index of refraction
of the oil is 1.2 and that of the glass is 1.6, what is the
minimum thickness of the oil film (other than zero)?
(a) 100 nm
(b) 200 nm
(c) 300 nm
(d) none
12
61134. In Young’s double-slit experiment, the intensity of light at
a point on the screen, where the path difference is 2, is I.
The intensity of light at a point where the path difference
becomes N3 is
(a) I
(b)
(d) I
12
612Two coherent light sources whose intensity ratio is 81: 1 produce interference fringes. If the ratio of intensities of maxima and minima in
the fringe system is x:y. Find ( x-y ? )
12
613State whether True or False:
The shape of the wave front originating from a line is spherical
A. True
B. False
12
614Which of these waves can be polarised?
A. Sound waves
B. Longitudinal waves on a string
C. Transverse waves on a string
D. Light waves
12
615Two speakers A and B are placed 1 ( mathrm{m} )
apart, each produces sound waves of frequency ( 1800 mathrm{Hz} ) in phase. ( mathbf{A} )
detector moving parallel to the line joining the speakers at a distance of 2.4
( m ) away detects a maximum intensity
at 0 and then at ( P . ) Speed of the sound
wave is:
( A cdot 330 mathrm{ms}^{-1} )
B. 360 ( mathrm{ms}^{-1} )
c. ( 350 mathrm{ms}^{-1} )
D. ( 340 mathrm{ms}^{-1} )
12
616The optical instrument which is used in every cricket match is.:
A. simple microscope
B. Compound microscope
c. Astronomical telescope
D. Binocular
12
617In Young’s double slit experiment, one of the slit is wider than another, so that
amplitude of the light from one slit is
double of that from other slit. If ( boldsymbol{I}_{m} ) be
the maximum intensity, the resultant intensity I when they interfere at phase difference ( phi ) is given by
A ( cdot frac{I_{m}}{9}(4+5 cos phi) )
в. ( frac{I_{m}}{3}left(1+2 cos ^{2} frac{phi}{2}right) )
c. ( frac{I_{m}}{5}left(1+4 cos ^{2} frac{phi}{2}right) )
D. ( frac{I_{m}}{9}left(1+8 cos ^{2} frac{phi}{2}right) )
12
618Photoelectric effect supports the
quantum nature of light because
This question has multiple correct options
A. There is minimum frequency of light below which no photoelectrons are emitted
B. The maximum KE of photoelectrons depends only on the frequency of light and not on its intensity
C. Even when the metal surface is faintly illuminated by light of wavelength less than the threshold wavelength, the photoelectrons leave the surface immediately
D. Electric charge of photoelectrons is quantized
12
619When a drop of oil is spread on a water
surface, it displays beautiful colors in daylight because of
A. dispersion of light
B. reflection of light
c. polarization of light
D. interference of light
12
620A string of length 0.4 m and mass ( 10^{-2} k g ) is tightly clamped at its ends.
The tension in the string is ( 1.6 N ) Identical wave pulses are produced at one end at equal intervals of time ( Delta t )
The value of ( Delta t ) which allows
constructive interference between
successive pulses is
A . ( 0.05 s )
B. ( 0.10 s )
c. ( 0.20 s )
D. ( 0.40 s )
12
621The source is at some distance from an
obstacle. Distance between obstacle
and the point of observation is ( b ) and
wavelength of light is ( lambda ). The distance of
( boldsymbol{n}^{t h} ) Fresnel Zone from the point
of observation is :
A ( cdot frac{b n lambda}{2} )
в. ( _{b-} frac{n lambda}{2} )
c. ( _{b+frac{n lambda}{2}} )
D. ( b-n lambda )
12
622Diffraction of light was discovered by :
A. Young
B. Hertz
c. Grimaldi
D. Malus
12
623In Young’s double slit experiment, the
source ( S ) and two slits ( A ) and ( B ) are
lying in a horizontal plane. The slit ( boldsymbol{A} ) is
above slit ( B ). The fringe are obtained on
a vertical screen ( K . ) The optical path
from ( S ) to ( B ) is increased by putting a
transparent material of higher refractive indices. The path from ( boldsymbol{S} ) to ( boldsymbol{A} )
remains unchanged. As a result of this, the result fringe pattern moves some what
A. upwards
B. downwards
c. towards left horizontally
D. towards right horizontally
12
624The angle of incidence at which
reflected light is totally polarized for
reflection from air to glass (refractive
index ( n ) ), is:
( A cdot sin ^{-1} )
B. ( sin ^{-1}(1 / mathrm{n}) )
( c cdot tan ^{-1}(1 / mathrm{n}) )
D. ( tan ^{-1}(n) )
12
6253. To demonstrate the phenomenon of interference, we
require two sources which emit radiation
(a) of the same frequency and having a definite phase
relationship
(b) of nearly the same frequency
(c) of the same frequency
(d) of different wavelengths
(AIEEE 2003)
12
626If ( A ) is the amplitude of the component waves, the resultant amplitude of two waves that interfere to produce destructive interference is
( A cdot 2 A )
B. A
( c cdot 0 )
D. – –
12
627If ( i ) is the angle of incidence, the angle
between the incident wave front and the
normal to the reflecting surface is
( mathbf{A} cdot i )
B. ( 90^{circ}-i )
( mathbf{c} cdot 90^{circ}+i )
D . ( i-90^{circ} )
12
628In YDSE ratio of width of slit is 4: 1
then ratio of maximum to minimum
intensity
( mathbf{A} cdot mathbf{9} )
B . 27
( c .3 )
D. 81
12
629A narrow monochromatic beam of light intensity I is incident on a glass plate. another identical glass plate is kept close to the first one and parallel to it
Each glass plate reflects ( 25 % ) of the light incident on it and transmit the
remaining. find the ratio of the
minimum and maximum intensity in the interference pattern formed by the two beams obtained after 1 reflection at
each plate.
( mathbf{A} cdot 1: 49 )
B. 49: 1
c. 1: 23
D. 23: 1
12
630The reflected and refracted rays are
observed to be perpendicular to each other, when ray of light is incident at an
angle of ( 60^{circ} ) on a transparent block. The refractive index of that block is:
( A cdot frac{3}{2} )
B. ( frac{1}{2} )
c. ( frac{2}{sqrt{3}} )
D. ( sqrt{3} )
12
631The objective lens of an optical instrument is an achromat
combination with a focal length of
( 90 mathrm{cm} . ) The two lenses possess
dispersive powers 0.024 and 0.036 respectively and are in contact with each other. Then their focal lengths are:
A. ( -30 mathrm{cm}, 45 mathrm{cm} )
в. ( 45 mathrm{cm}, 30 mathrm{cm} )
c. ( 30 mathrm{cm},-45 mathrm{cm} )
D. 30 ( c m,-30 mathrm{cm} )
12
632A plane polarized light is incident on a polariser with its pass axis making
angle ( theta ) with ( x ) -axis, as shown in the
figure. At four different values of ( boldsymbol{theta}, boldsymbol{theta}= )
( 8^{circ}, 38^{circ}, 188^{circ} ) and ( 218^{circ}, ) the observed
intensities are same. What is the angle
between the direction of polarization
and ( x ) -axis
( mathbf{A} cdot 203^{circ} )
В. ( 45^{circ} )
( c cdot 98^{circ} )
( D cdot 128^{circ} )
12
633Constructive and destructive
interference occur in:
A. cosmic rays
B. light raus
c. sound waves
D. water waves
E. All of these
12
634In young’s double-slit experiment using mono chromatic light of wavelength ( mathbf{A} ) the intensity of light at a point on the
screen where path difference is ( lambda ) is ( K ) units. What is the intensity if light at a point where path difference is ( lambda / 3 ? )
12
63526 Light is incident at an angle o with the normal to a plane
containing two slits of
separation d. Select the
expression that correctly
describes the positions of
the interference maxima in
terms of the incoming
angle and outgoing angle
no
(a) sin 0 + sin
=
C 12
m +=
(b) d sin 0 = ma
(c) sin
– sin
= (m + 1)
(d) sin 0+ sin
= m
12
636Four light waves are represented by
( (i) y=a_{1} sin omega t )
( (i i) y= )
( a_{2} sin (omega t+varepsilon) )
( (i i i) y=a_{1} sin 2 omega t quad(i v) y= )
( boldsymbol{a}_{2} sin 2(boldsymbol{omega} boldsymbol{t}+boldsymbol{varepsilon}) )
Interference fringes may be observed due to superposition of This question has multiple correct options
A ( cdot(i) ) and ( (i i) )
B. ( ( i ) ) and (iii)
c. ( ( i i ) ) and ( (i v) )
D. (iii) and (iv)
12
637Write definitions of plane of vibration and plane of polarization. Explain the working process to obtain plane polarized light by Nicole Prism. Draw necessary diagram.12
638The maximum intensity produced by
two coherent waves of intensity ( boldsymbol{I}_{1} ) and
( boldsymbol{I}_{2} ) will be
A ( cdot I_{1}+I_{2} )
В ( cdot I_{1}^{2}+I_{2}^{2} )
( mathbf{c} cdot I_{1}+I_{2}+2 sqrt{I_{1} I_{2}} )
D. zero
12
639Determine the difference ( L_{1}-L_{2}(= )
( Delta L) ) in terms of ( lambda_{0} )
A ( frac{4 lambda_{0}}{mu} )
в. ( frac{7 lambda_{0}}{2 mu} )
( c cdot frac{3 lambda_{0}}{mu} )
D. none of the above
12
640The velocity of light in air is ( 3 times )
( 10^{8} m s^{-1} ) and that in water is ( 2.2 times )
( 10^{8} m s^{-1} . ) The polarising angle of
incidence is:
A . 45
B. ( 50^{circ} )
c. ( 53.74^{circ} )
D. ( 63^{circ} )
12
641In Fresnel’s biprism expt., a mica sheet of refractive index 1.5 and thickness ( 6 x )
( 10^{-6} mathrm{m} ) is placed in the path of one of interfering beams as a result of which the central fringe gets shifted through 5 fringe widths. The wavelength of light used is
A ( cdot 6000 stackrel{circ}{A} )
в. ( 8000 stackrel{circ}{A} )
c. 4000 ,
D. ( 2000 stackrel{circ}{A} )
12
642State Brewster’s law of polarization of
light.
12
643In Fraunhoffer diffraction experiment, is the distance between screen and the obstacle, b is the size of obstacle and ( lambda )
is wavelength of incident light. The general condition for the applicability of Fraunhoffer diffraction is:
( ^{mathbf{A} cdot} cdot frac{b^{2}}{l lambda}>>1 )
B. ( frac{b^{2}}{l lambda}=1 )
c. ( frac{b^{2}}{l lambda}<<1 )
D. ( frac{b^{2}}{l lambda} neq 1 )
12
644The maximum number of possible interference maxima, for slit separation equal to twice the wavelength,in Young’s double slit experiment is :
A . infinite
B. five
c. three
D. zero
12
645JUU
o
CP represents a wavefront
and AO and BP, the
corresponding two
rays. Find the condition
on for constructive
interference at P between
the ray BP and reflected
ray OP
(a) cos O = 32d
(c) seco – cos 0 = Nd
A/
(b) cos O = N4d
(d) seco – cos 0 = 4Nd
12
64647. In a Fresnel’s diffraction arrangement, the screen is at a
distance of 2 meter from a circular aperture. It is found
that for light of wavelengths 2, and 12, the radius of 4th
zone for 2, coincides with the radius of 5th zone for
Then the ratio 1:1, is
(a) 74/5
(b) 1574
(c) 5/4
(d) 4/5
12
647If two sources have a randomly varying phase difference ( varphi(t) ) the resultant
intensity will be given by
A. ( I_{0} )
в. ( frac{I_{0}}{2} )
c. ( 2 I_{0} )
D. ( frac{I_{0}}{sqrt{2}} )
12
648In the diffraction pattern due to a single slit of width ‘ ( d ) with incident light of
wavelength ‘ ( lambda^{prime}, ) at an angle of
diffraction ‘ ( boldsymbol{theta}^{prime} ), the condition for first
minimum is
( mathbf{A} cdot lambda sin theta=d )
B. ( d cos theta=lambda )
( mathbf{c} cdot d sin theta=lambda )
( mathbf{D} cdot lambda cos theta=d )
12
649One of the two slits in YDSE is painted over, so that it transmits only light
waves having intensity half of the intensity of the light waves having half of the intensity of the light waves through the other slit. As a result of this
A. fringe pattern disappears
B. bright fringes become brighten and dark ones become darker
c. dark and bright fringes get fainter
D. dark fringes get brighter and bright fringes get darker
12
650In Young’s double slit experiment the two slits are illuminated by light of
wavelength ( 5890^{circ} mathrm{A} ) and the distance between the fringes obtained on
the screen is ( 0.2^{circ} . ) If the whole
apparatus is immersed in water then
the angular fringe width will be (refractive index of water is ( 4 / 3 ) ):
A .0 .30
then 0.0 .030
в. ( 0.15^{circ} )
( c cdot 15 )
D. ( 30^{circ} )
12
651Among the Fresnel zones the operative zones contributing intensity are :
A. last zones
B. first few zones
c. middle zones
D. all the zones
12
652Light transmitted by nicol prism is
A. unpolarised
B. plane polarised
c. circular polarised
D. elliptically polarised
12
653Two polaroids ( A ) and ( B ) are kept with
their transmission axis at an angle ( theta )
with respect to one another. If the
transmitted intensity of light is ( boldsymbol{I}_{t}= )
( 0.75 I_{0}, ) where ( I_{0} ) is the intensity of light
incident on the system, then ( theta ) is:
A ( cdot 30^{circ} )
B . ( 45^{circ} )
( c cdot 60^{circ} )
D. ( 90^{circ} )
12
654A parallel beam of monochromatic unpolarised light is incident on a transparent dielectric plate of refractive index ( frac{1}{sqrt{3}} . ) The reflected beam is completely polarised. Then the angle of incidence is
( A cdot 30^{circ} )
B. ( 60^{circ} )
( c cdot 45^{circ} )
D. ( 75^{circ} )
12
65551. Two Nicols are oriented with their principal planes making
an angle of 60°. The percentage of incident unpolarized
light which passes through the system is
(a) 50%
(b) 100%
(c) 12.5%
(d) 37.5%
12
656Which vector, electric or magnetic, is
used to represent the polarisation of
e.m. waves? How will you show that light
waves are transverse in nature??
12
657In the phenomena of diffraction of light, when blue light is used in the experiment in spite of red light, then
A. fringes will become narrower
c. no change in fringe width
D. None of these
12
658A ray of light is incident on a thin film.
As shown in the figure, ( M ) and ( N ) are
two reflected rays while ( P ) and ( Q ) are two
transmitted rays. Rays ( N ) and ( Q )
undergo a phase change of ( pi ). correct
ordering of the refracting indices is
A ( cdot n_{2}>n_{3}>n_{1} )
в. ( n_{3}>n_{2}>n_{1} )
( mathbf{c} cdot n_{3}>n_{1}>n_{2} )
D. none of these, the specified changes cannot occu
12
659Two coherent waves are described by
the expressions ( E_{1}=E_{0} sin left(frac{2 pi x_{1}}{lambda}-2 pi f t+frac{pi}{6}right) )
( E_{2}=E_{0} sin left(frac{2 pi x_{2}}{lambda}-2 pi f t+frac{pi}{8}right) )
Determine the relationship between ( boldsymbol{x}_{1} )
and ( x_{2} ) that produces constructive
interference when the two waves are
superposed
12
660Light travels in a straight line because:
A. it is not absorbed by atmosphere
B. its velocity is very high
c. diffraction effect is negligible
D. due to interference
12
66166. In Young’s double-slit experiment, the first maxima is
observed at a fixed point P on the screen. Now, the screen
is continuously moved
away from the plane of
slits. The ratio of
intensity at point P to the 1
intensity at point O
(center of the screen)
(a) remains cosntant
(b) keeps on decreasing
(c) first decreases and then increases
(d) first decreases and then becomes constant
12
662Which letter represents the wavelength
of the light in the Young’s double slit
experiment?
( A cdot A )
B. B
( c . c )
D.
( E )
12
663Sun light filtering through the tree leaves often makes circular patches on
the ground because:
A. the sun is round
B. the space through which light penetrates is round
c. light is transverse in nature
D. of diffraction effects
12
664Give analytical treatment of YDSE
interference bands and hence obtain
the expression for fringe width.
12
665Interference fringes are obtained due to the interference of waves from two
coherent sources of light with
amplitudes ( a_{1} ) and ( a_{2}left(a_{1}=2 a_{2}right) . ) What
is the ratio of the maximum and
minimum intensities of light in the
interference pattern?
A .2
B. 4
( c .9 )
D. ( infty )
12
666Find fringe width and number of
possible maxima on the screen ( boldsymbol{E} )
A. ( 1.1 m m, 8 )
B. ( 1.1 m m, 9 )
c. ( 0.8 m m, 8 )
D. ( 0.9 m m, 9 )
12
667When an unpolarized light of intensity
( I_{0} ) is incident on a polarizing sheet, the intensity of the light which does not get transmitted, is :
A . zero
В. ( I_{0} )
c. ( frac{I_{0}}{2} )
D. ( frac{I_{0}}{4} )
12
668Write the definition of wavefront.12
669The angle between the axes of two polaroids so as to reduce the intensity of the incident unpolarised light to ( 1 / 3 )
and ( 1 / 10 ) are ( left(operatorname{given}, cos 35^{circ}=0.8192right. )
and ( left.cos 63^{circ}=0.4540right) )
A ( .35^{circ}, 63^{circ} )
в. ( 55^{circ}, 27^{circ} )
( c cdot 63^{circ}, 35 )
D. ( 27^{circ}, 55^{circ} )
12
670A wave pulse traveling on a two piece string, gets partially reflected and partially transmitted at the junction. The reflected wave is inverted in shape as compared to incident one. If the
incident wave has wavelength ( lambda ) and
transmitted wave has ( lambda^{prime}, ) then
( A cdot lambda^{prime}>lambda )
B . ( lambda^{prime}=lambda )
c. ( lambda^{prime}<lambda )
D. none
12
671When light waves suffers reflection at the interface from air to glass, the change in phase of reflected waves is
equal to
A . 0
в. ( frac{pi}{2} )
c. ( pi )
D. ( 2 pi )
12
672Consider a young’s doluble slit experiment as shown in figure. What
should be the slit seperation din term
of wavelength ( lambda ) such that the first
minima occurs directly in front of the
slit ( left(boldsymbol{S}_{1}right) ? )
( A )
B.
c. ( frac{lambda}{(sqrt{5}-2)} )
D. ( frac{lambda}{2(sqrt{5}-2)} )
12
67318. If one of the two slits of Young’s double-slit experime
is painted so that it transmits half the light intensity as
second slit, then
(a) the fringe system will altogether disappear
(b) the bright fringes will become brighter and the dark
fringes will become darker
(c) both dark and bright fringes will become darker
(d) dark fringes will become brighter and bright fringes
darker
12
674The amplitude of two interfering waves are ( a ) and ( 2 a ) respectively. The resultant amplitude in constructive interference
will be
( mathbf{A} cdot 5 a )
B. ( a )
( c cdot 3 a )
D. ( 2 a )
12
675The path difference between two wavefronts emitted by coherent sources ( o )
of wavelength ( 5460 A ) is 2.1 micron. The phase difference between the wavefronts at that point is
A. 7.962
в. 7.962 ( pi )
c. ( frac{7.962}{pi} )
D. ( frac{7.962}{3 pi} )
12
676In Young’s double slit experiment, the two equally bright slits are coherent, but of phase difference ( frac{pi}{3} . ) If maximum
intensity on the screen is ( I_{o} ), the
intensity at the point on the screen equidistant from the slits is:
A ( cdot I_{o} )
в. ( frac{I_{o}}{2} )
c. ( frac{I_{o}}{4} )
D. ( frac{3 I_{o}}{4} )
12
677In young’s double slit experiment ( beta ) is
the fringe width and ( I_{o} ) is the intensity of the central bright fringe. What will be the intensity at a distance ( x ) from the central bright fringe?
( mathbf{A} cdot_{mathrm{l}_{o}} cos left(frac{x}{beta}right) )
B ( cdot cos ^{2}left(frac{x}{beta}right) )
( ^{mathrm{c}} cdot_{1_{0} cos ^{2}}left(frac{pi x}{beta}right) )
D. ( left(frac{I_{o}}{4}right) cos ^{2} frac{pi x}{beta} )
12
678Write down four differences between
interference and diffraction.
12
679Draw the intensity pattern for single slit diffraction and double slit interference.
Hence, state two differences between
interference and diffraction patterns.
12
680Consider an YDSE that has different
slits width, as a result, amplitudes of
waves from two slits are ( A ) and ( 2 A )
respectively. If ( I_{0} ) be the maximum
intensity of the interference pattern,
then intensity of the pattern at a point
where phase difference between waves
is ( phi ) is :
( mathbf{A} cdot I_{0} cos ^{2} phi )
B. ( frac{I_{0}}{3} sin ^{2} frac{phi}{2} )
c. ( frac{I_{0}}{9}[5+4 cos phi] )
D ( cdot frac{I_{0}}{9}[5+8 cos phi] )
12
681The following cannot be explained by wave nature of light
A . Interference
B. Photo electric effect
c. Diffraction
D. Refraction
12
682At ( t=2 s, ) the position of central
maxima is
A. ( 2 m m ) above ( C )
B. ( 2 m m ) below ( C )
( mathrm{c} .4 mathrm{mm} ) above ( C )
D. ( 4 m m ) below ( C )
12
683In single slit diffraction pattern
A. Centre fringe has negligible width than others.
B. All fringes are of same width
C . Central fringe does not exist
D. None of the above
12
684Sketch the emergent wavefront12
685In Young’s double-slit experiment, the ( y- ) coordinates of central maxima and 10 th
maxima are ( 2 c m ) and ( 5 c m ), respectively
When the YDSE apparatus is immersed
in a liquid of refractive index ( 1.5, ) the corresponding y-coordinates will be
( mathbf{A} cdot 2 c m, 7.5 c m )
B. ( 3 mathrm{cm}, 6 mathrm{cm} )
( mathbf{c} .2 mathrm{cm}, 4 mathrm{cm} )
D. ( 4 / 3 c m, 10 / 3 c m )
12
686Young’s expt. the ratio of intensity at maxima and minima in the interference
pattern is The ( 25: 9 . ) The ratio of slit
width will be
( A cdot 4: 1 )
B. 2:1
( c cdot 16: 1 )
D. 8: 1
12
687The fringe width for red colours as compared to that for violet colour is approximately
A. 3 times
B. 2 times
c. 4 times
D. 8 times
12
688Unpolarised and Polarised Light.12
68924. A plate of thickness t made of a material of refractive
index u is placed in front of one of the slits in a double-
slit experiment. What should be the minimum thickness
t which will make the intensity at the center of the fringe
pattern zero?
(a) (u – 1)
(b) (u – 1) 2
(C) 2(4-1)
(d) – 4
(M-1)
12
690A parallel beam of light of wavelength ( 560 mathrm{nm} ) falls on a thin of oil (refractive
index ( =1.4 ) ) What should be the
minimum thickness of the film so that
it weakly transmits the light
12
691In YDSE using monochromatic visible light, the distance between the plane of slits and the screen is ( 1.7 m . ) At point ( P )
on the screen which is directly in front of the upper slit, maximum path is observed. Now, the screen is moved
( 50 c m ) closer to the plane of slits. Point
( P ) now lies between third and fourth
minima above the central maxima and
the intensity at ( P ) is one-fourth of the maximum intensity on the screen. Find the wavelength of light if the separation of slits is ( 2 m m )
A. ( 2.9 times 10^{-7} mathrm{m} )
В. ( 3.9 times 10^{-7} mathrm{m} )
c. ( 5.9 times 10^{-7} m )
D. ( 6.9 times 10^{-7} ) т
12
6929. When an unpolarised light of intensity 1, is incident on a
polarising sheet, the intensity of the light which does not
get transmitted is
(a) lo
(b) zero
(AIEEE 2005)
12
693Two identical coherent sources are
placed on a diameter of a circle of
radius ( R ) at separation ( x(<<R) )
symmetrically about the centre of the circle. The sources emit identical
wavelength ( lambda ) each. The number of points on the circle with maximum intensity is ( (x=5 lambda) )
12
694What will be the distance between two
slits which, when illuminated by light of
wavelength ( 5000 A^{circ}, ) produce fringes of
width ( 0.5 m m ) on a screen distant 1
meter from the slits?
( mathbf{A} cdot 10^{-2} ) meter
B . ( 10^{-3} ) meter
( mathbf{c} cdot 10^{-4} ) meter
D. ( 10^{-6} ) meter
12
6957. Two point white dots are 1 mm apart on a black
paper. They are viewed by eye of pupil diameter 3 m.
Approximately, what is the maximum distance at which
these dots can be resolved by the eye? (Take wavelength
of light as 500 nm.)
(a) 3 m
(b) 6 m
(c) 1 m
(d) 5 m (AIEEE 2005)
12
696A beam of width ( t ) is incident at 45 o on
air-water boundary. The width of the
beam in water is
12
697Sets of travellling waves are given as shown in above figure. Identify which of
the following set of wave will soon show
constructive interference?
( A cdot A )
B. B
( c cdot c )
D.
E.
12
698Sound waves from a tuning fork ( boldsymbol{F} ) reach
a point ( boldsymbol{P} ) by two separate routes ( boldsymbol{F} boldsymbol{A} boldsymbol{P} )
and ( F B P . F B P ) is ( 12 mathrm{cm} ) larger than
FAP.There is silence at ( P ). If the
separation becomes ( 2 mathrm{cm} ), the sound
becomes maximum at ( P ) and at ( 36 c m )
there is again silence and so on. The least frequency of tuning fork is
A . 1357 Hz
в. 1735 нz
c. ( 1375 mathrm{Hz} )
D. 1400 нz
12
69917. A beam of unpolarised light of intensity 10 is passed
through a polaroid A and then through another polaroid
B which is oriented so that its principal plane makes an
angle of 45° relative to that of A. The intensity of the
emergent light is:
(a) 10/2
(b) 1/4
(c) 10/8
(d) I (JEE Main 2013)
12
700For a parallel beam of monochromatic light of wavelength ( ^{prime} lambda^{prime}, ) diffraction is produced by a single slit whose width ‘a is of the order of the wavelength of the light. If ‘D’ is the distance of the screen
from the slit, the width of the central
maxima will be
( ^{text {A }} cdot frac{D a}{lambda} )
B. ( frac{2 D a}{lambda} )
c. ( frac{2 D lambda}{a} )
D. ( frac{D lambda}{a} )
12
701Fill in the blank with appropriate
In Young’s double slit experiment, the path difference between two interfering waves at a point on the screen is ( frac{5 lambda}{2}, lambda ) being wavelength of the light used. The dark fringe will lie at this point.
12
702The bending of light near the edges of an obstacle and spreading into the region of geometrical shadow is called
A . Interference
B. Diffraction
c. Polarization
D. Doppler effect
12
703In optical instruments, the lenses are
used to form images by :
A. Reflection
B. Refraction
c. Dispersion
D. Scattering
12
704In a YDSE with identical slits, the
intensity of the central bright fringe is
( I_{0} . ) If one of the slits is covered, the intensity at the same point is
A ( cdot 2 I_{0} )
в. ( I_{0} )
( c cdot I_{0} / 2 )
D. ( I_{0} / 4 )
12
705In an interference experiment, monochromatic light is replaced by white light we will see:12
706Unpolarized light passes through two
polaroids, the axis of one is vertical and
that of the other is ( 30^{circ} ) to the vertical.
What is the orientation and intensity of
the transmitted light?
A. Plane polarized at ( 60^{circ} ) to the vertical and having intensity ( frac{l_{0}}{4} )
B. Plane polarized at ( 30^{circ} ) to the vertical and having intensity of ( frac{3 l_{0}}{8} )
C. Plane polarized at ( 30^{circ} ) to the vertical and having intensity ( frac{l_{0}}{2} )
D. No light passes
12
707Light of wavelength ( 6328 A ) is incident normally on a slit having a width of
( 0.2 m m . ) The angular width of the central maximum measured from
minimum to minimum of diffraction
pattern on a screen 9.0 meters away will
A. 0.36 degree
B. 0.18 degree
c. 0.72 degree
D. 0.09 degree
12
708Monochromatic light is incident on a pair of narrow slits a distance of ( 0.1 mathrm{mm} )
apart. A series of
bright and dark fringes are observed on a screen a distance of ( 2.0 mathrm{m} ) away. The
distance between
adjacent bright fringes is ( 8.0 mathrm{mm} ) What is the path difference between the
light waves from the two slits that meet
at the second
order dark fringe?
A ( cdot 2.0 times 10^{-7} mathrm{m} )
В. ( 4.0 times 10^{-7} mathrm{m} )
( mathbf{c} cdot 6.0 times 10^{-7} m )
7
12
709A parallel beam of monochromatic light is incident normally on a narrow slit. A diffraction pattern is formed on a screen placed perpendicular to the direction of the incident beam. At
the first minimum of the diffraction
pattern, the phase difference between the rays coming from the two edges of the slit is :
A. zero
в. ( frac{pi}{2} )
( c )
D. ( 2 pi )
12
710Which theory of light proposed the presence of ether medium for propogation of light?12
711115410
monochromatic point source emitting
light of wavelength ( lambda=500 ) nm. A thin
lens of circular shape of focal length ( 0.10 m ) is cut into two identical halves
( L_{1} ) and ( L_{2} ) by a plane passing through a
diameter. The two halves are placed
SO with a gap of 0.5 mm. The distance
along the axis from ( S ) to ( L_{1} ) and ( L_{2} ) is
( 0.15 m, ) while that from ( L_{1} ) and ( L_{2} ) to ( O )
is 1.30 m. The screen at ( O ) is normal to
( boldsymbol{S O} )
If the third intensity maximum occurs
at point ( A ) on the screen, find distance
OA in mm.
12
712Two identical sound waves each of
loudness ( beta ) interfere constructively at a
point to produce a sound level of
( mathbf{A} cdot 6 beta )
B. ( 3 beta )
( mathbf{c} cdot beta+3 )
( mathbf{D} cdot beta+6 )
12
713The de Broglie wave present in fifth Bohr orbit is
( A )
в.
( c )
D.
12
714If one of the two slits of Young’s doubleslit experiment is painted so that it transmits half the light intensity as the second slit, then
A. fringe system will altogether disappear
B. bright fringes will become brighter and the dark fringes will become darker
c. both dark and bright fringes will become darker
D. dark fringes will become less dark and bright fringes will become less bright
12
71512. Following transverse waves,
y = 2sin (100 – 5.3x),
y = 212 sin(100 – 5.3x+5)
and y3 = sin (100t – 5.3x)
superpose in a homogenous medium. Find the resultant
amplitude at x = 0.
(a) 1 unit
(b) 4 unit
(c) 5 unit
(d) 2 unit
12
716Light waves travel in a vacuum, along the ( X ) -axis. Which of the following may
represent the wave fronts?
( mathbf{A} cdot x=c )
В. ( y=c )
( mathbf{c} cdot z=c )
D. ( x+y+z=c )
12
717In Young’s double slit experiment, the
two slits act as coherent sources of
equal amplitude ( A ) and wavelength ( lambda ). In
another experiment with the same set up the two slits are same of equal amplitude of wavelength ( lambda ) but are
incoherent. The ratio of intensity of light at the mid point of the screen in the first to the second case is?
A . 4: 1
B . 2: 1
( c cdot 1: 1 )
D. 1: 2
12
7188. If 1, is the intensity of the principal maximum in the
single-slit diffraction pattern, then what will be its
intensity when the slit width is doubled?
10
0
(b) 10
(c) 41
(d) 21
(AIEEE 2005)
(a) 2
12
719The frequencies of two sound sources are ( 256 mathrm{Hz} ) and ( 260 mathrm{Hz}, ) At ( mathrm{t}=0, ) the intensity of sound is maximum. Then
the phase differance at the time ( t=1 / 16 )
sec will be
A. zero
в. ( pi )
c. ( pi / 2 )
D. ( pi / 4 )
12
720( M_{1} ) and ( M_{2} ) are plane mirrors and kept
parallel to each other. At point 0 , there
will be a maxima for wavelength ( lambda ). Light
from a monochromatic source ( boldsymbol{S} ) of
wavelength ( lambda ) is not reaching directly on
the screen. Then, ( lambda ) is:
( ^{A} cdot frac{3 d^{2}}{D} )
B. ( frac{3 d^{2}}{text { on }} ) ( 2 D )
( c cdot underline{d^{2}} )
( bar{D} )
D. ( 2 d^{d} )
12
721Name any two characteristics of light explained by Huygens wave theory?12
722The intensity of the light coming from
one of the slits in a Young’s double slit
experiment is double the intensity from
the other slit. Find the ratio of the
maximum intensity to the minimum intensity in the interference fringe
pattern observed.
12
72329. In a two-slit experiment with white light, a white fringe
is observed on a screen kept behind the slits. When the
screen in moved away by 0.05 m, this white fringe
(a) does not move at all
(b) gets displaced from its earlier position
(c) becomes colored
(d) disappears
12
724A Young’s double slit experiment is conducted with slit separation ( 10 mathrm{mm} ) where the screen is ( 2 mathrm{m} ) away from the
slits. If wavelength of light used is ( 6000 AA, ) then fringe width in ‘mm’ is
A . 0.12
B. 0.24
c. 0.36
D. 0.48
12
725Two identical coherent sources of
wavelength ( lambda ) are placed at ( (100 lambda, 0) ) and ( (-50 lambda, 0) ) respectively. A detector moves slowly from the origin to ( (50 lambda, 0) ) along x-axis. The number of maxima and minima detected are, respectively [include origin and ( (50 lambda, 0)] )
A. 51 and 50
B. 101 and 100
c. 49 and 50
D. 50 and 49
12
72665. In a standard Young’s double-slit experiment with coherent
light of wavelength 600 nm, the fringe width of the fringes
in the central region (near
the central fringe, Po) is
observed to be 3 mm. An
extremely thin glass plate
is introduced in front of the 2= 600 nm
first slit, and the fringes are
observed to be displaced
by 11 mm. Another thin
plate is placed before the second slit and it is observed that
the fringes are now displaced by an additional 12 mm. If the
additional optical path lengths introduced are A, and A2, then
(a) 1141 = 1242 (b) 124, = 1142
(c) 114, >1242 (d) none of the above
12
727Two waves having the intensities in the ratio 9: 1 produce interference. The ratio of maximum to minimum intensity is equal to
( A cdot 4: 1 )
B. 9: 1
( c cdot 2: )
D. 10: 8
12
728Green light is incident at the polarising angle on a certain transparent medium.
The angle of refraction is ( 30^{circ} . ) Find
(i) polarising angle, and
(ii) refractive index of the medium.
12
729An un-publicized beam of intensity ( 2 a^{2} )
passes through a thin Polaroid. Assuming zero absorption in the Polaroid the intensity of emergent planes polarized light is
( mathbf{A} cdot 2 a^{2} )
в. ( a^{2} )
c. ( sqrt{2} a^{2} )
D. ( frac{a^{2}}{2} )
12
730In YDSE ratio of width of slit is 4: 1
then ratio of maximum to minimum
intensity
( mathbf{A} cdot mathbf{9} )
B . 27
( c .3 )
D. 81
12
73152. Unpolarized light falls on two polarizing sheets placed
one on top of the other. What must be the angle between
the characteristic directions of the sheets if the intensity
of the final transmitted light is one-third the maximum
intensity of the first transmitted beam
(a) 75°
(b) 55°
(c) 35°
d) 15°
12
732If the angle between the pass axis of the polarizer and the analyzer is 45 the ratio of the intensities of original
light and the transmitted light after passing through the analyzer is
A ( cdot frac{I}{2} )
B. ( frac{1}{3} )
( c )
D. ( frac{I}{4} )
12
733Two Nicols is oriented with their
principal planes making an angle of ( 60^{circ} )
The percentage of incidents unpolarized light which passes through the system are
( A cdot 50 % )
B. ( 100 % )
c. ( 12.5 % )
D. 37.5%
12
734To observe diffraction, the size of an
obstacle:
A. should be of the same order as wave length
B. should be much larger than the wave length
c. has no relation to wave length
D. may be greater or smaller than the wave length
12
735In Young’s double slit experiment the separation between the slits is halved and the distance between the slits and
screen is doubled. The fringe width is:
A. unchanged
B. halvedd
c. doubled
12
736Identify which of the following should be used for polarised light waves?
I. Sunglasses
Il. Remove ultraviolet light
III. Reveal stress patterns
A. I only
B. II only
c. I and III only
D. II and III only
E. I, II, and III
12
737In Young’s double slit experiment if the
slit widths are in the ratio ( 1: 9 . ) The
ratio of the intensity at minima to that at maxima will be :
A .
в. ( frac{1}{9} )
( c cdot frac{1}{4} )
D. ( frac{1}{3} )
12
738The wave front due to a source situated
at infinity is :
A. spherical
B. cylindrical
c. planar
D. none of these
12
program at the same amplitude ( A ) but
at slightly different frequencies ( n_{1} ) and ( n_{2} ) such that ( left(n_{1}-n_{2}right)=10^{3} H z . )
detector receives signals from both the stations simultaneously but only when
intensity of signal is greater than ( 2 A^{2} ) The time interval between two
successive maxima will be :
в. ( 10^{-2} ) s
( mathrm{c} cdot 10^{-3} s )
D. ( 10^{circ} )
12
74068. In YDSE, light of wavelength
2 = 5000 Å is used, which
emerges in phase from two
slits a distance d = 3 x 10-
m apart. A transparent sheets, 19 d sin
of thickness t = 1.5 x 10-‘m,
refractive index n = 1.17, is
placed over one of the slits.
Where does the central maxima of the interference now
appear from the center of the screen? (Find the value of y?)
D(u – 1)
2D (u – 1)
(a) –
2d
d
D(u + 1)
D(u – 1)
d
d
12
741The radius of a wavefront as the waves
propagate
A. decreases
B. increases
c. becomes zero
D. sometimes decreases and sometimes increases
12
742Slit 1 of Young’s double-slit experiment is wider than slit ( 2, ) so that the light
from slits are given as ( A_{1}=A_{0} sin omega t ) and ( A_{2}=A_{0} sin left(omega t+frac{pi}{3}right) . ) The
resultant amplitude and intensity, at a point where the path difference between them is zero, are ( A ) and ( I ) respectively.
Then
This question has multiple correct options
A ( cdot A=sqrt{3} A_{0} )
B ( cdot A=4 A_{0} )
( mathbf{c} cdot I propto 16 A_{0}^{2} )
D. ( I propto 3 A_{0}^{2} )
12
7431. The wavelengths of light used in an optical instrument
are 2, = 4000 Å and is = 5000 Å, then the ratio of their
respective resolving powers (corresponding to 2, and 2)
(a) 16:25
(b) 9:1
(d) 5:4
(c) 4:5
(AIEEE 2002)
12
744In Young’s experiment, the fringe width
was found to be ( 0.4 m m ). If the whole
apparatus is immersed in water of refractive index ( frac{4}{3}, ) the new fringe width in mm is :
A. 0.25
B. 0.30
( c cdot 0.40 )
D. 2.00
12
745State the conditions to get constructive and destructive interference of light.12
746Four light waves are represented by
(i) ( y=a_{1} sin omega t )
(ii) ( y=a_{2} sin (omega t+varepsilon) )
(iii) ( y=a_{1} sin 2 omega t(text { iv }) y=a_{2} sin 2(omega t+ )
( varepsilon )
We obtain sustained interference due to
super-position of This question has multiple correct options
( A cdot ) (i) and (ii)
B. (i) and (iii)
c. (ii) and (iv)
D. (iii) and (iv)
12
747A satisfactory photographic print is obtained at a distance of ( 2 mathrm{m} ) from a 60
Cd lamp when the exposure time is 10 s. The time of exposure required for the same quality print at a distance ( 4 mathrm{m} ) from a 120 Cd lamp is:
A. 5 s
B. 10 s
( c cdot 20 s )
D. 25 s
12
74844. What will be the angular width of central maxima
in Fraunhofer diffraction when light of wavelength
6000 Å is used and slit width is 12 x 10 cm.
12
749In case of theory of light nature of light
match the following:
List – I List – II
a) Light is a collection of
e) Newton’s theory photons
b) Light is a form of
f) Huygen’s theory electromagnetic wave
g) Maxwell’s
c) Light is a wave
d) Light is a stream of
h) Max planck’s corpuscles theory
( mathbf{A} cdot mathrm{a}-mathrm{h} ; mathrm{b}-mathrm{g} ; mathrm{c}-mathrm{f} ; mathrm{d}-mathrm{e} )
B. ( a-e ; b-f ; c-g ; d-h )
C. ( a-g ; b-h ; c-g ; d-f )
D. ( a-h ; b-g ; c-e ; d-f )
12
750Two coherent light sources each of
wavelength ( lambda ) are separated by a
distance ( 3 lambda ). The maximum number of
minima formed on line AB which runs
from ( -infty ) to ( +infty ) is
12
751In double-slit experiment using light wavelength ( 600 n m ), the angular width of a fringe formed on a distant screen is
( 0.1^{circ} . ) What is the spacing between the two slits?
12
752Two coherent sources of intensity ratio
9: 4 produce interference. The intensity
ratio of maxima and minima of the
interference pattern is:
( mathbf{A} cdot 13: 5 )
B. 5: 1
c. 25: 1
D. 3: 2
12
753Blue light of wavelength 480 nm is most strongly reflected off a thin film of oil on a glass slab when viewed near normal incidence. Assuming that the
index of refraction of the oil is 1.2 and
that of the glass is ( 1.6, ) what is the minimum thickness of the oil film
(other than zero)?
This question has multiple correct options
A . ( 100 n m )
B. 200nm
c. 300 nm
D. None
12
754In Young’s double-slit experiment, the angular width of a fringe formed on
a distant screen is ( 1^{circ} . ) The slit
separation is ( 0.01 mathrm{mm} . ) The wavelength of the light is
A. ( 0.174 mathrm{nm} )
в. 0.174 А
c. ( 0.174 mu m )
D. ( 0.174 times 10^{-4} mathrm{m} )
12
755The light of wavelength ( 6328 A^{circ} ) is incident on a slit of width 0.2 mm
perpendicularly, the angular fringe width will be:
A ( cdot 0.36^{circ} )
B. ( 0.18^{circ} )
( c cdot 0.72^{circ} )
D. ( 0.09^{circ} )
12
756Instead of using two slits, if we use two separate identical sodium lamps in Young’s experiment, which of the following will occur?
A. General illumination
B. Widely separate interference
c. very bright maxima
D. Very dark minima
12
757The helical structures of nucleic acids
can be studied by using:
A. Interference phenomenon
B. Diffraction pattern
C. Polarised light
D. Photoelectric effect
12
758White light is used to illuminate the two slits b distance apart and the
screen is placed at a distance directly
in front of one of the slits on the screen.
It is found that certain wavelength are missing then find the wavelength if ( (b<<d) )
12
759Two small loud speakers ( A ) and ( B ) are
driven by the same amplifier as shown in Fig and emit pure sinusoidal waves
in phase. Speaker ( A ) is ( 1 mathrm{m} ) away as
shown and speaker ( B ) is 2 m away from the amplifier. The microphone is ( 4 mathrm{m} )
away from the amplifier in transverse direction as indicated in the Figure. For what frequencies destructive
interference will occur at ( P: )
A. 500 HZ, 1500 нZ, 2500 Hz,…
B. 500 Нz, 1000 Нz, 1500 Нz,…
c. 1250 Нz, 1750 Нz, 2250 Нz,..
D. 1000 Hz, 2000 Hz
12
760wavelength ( 6000 A ) is placed at a very
small height h above a flat reflecting
surface ( M N ) as shown in the figure. The
intensity of the reflected light is ( 36 % ) of the incident intensity. Inference fringes
are observed on a screen placed paralle to the reflecting surface at a very large
distance ( D ) from it. If the intensity at ( p )
be maximum, then the minimum
distance through which the reflecting
surface ( M N ) should be displaced so
that at ( P ) again becomes maximum?
( A cdot 3 times 10^{-7} mathrm{m} )
B . ( 6 times 10^{-7} mathrm{m} )
C. ( 1.5 times 10^{-7} mathrm{m} )
D. ( 12 times 10^{-7} mathrm{m} )
12
761In a YDSE apparatus, if we use while light then :
A. the fringe next to the central will be red
B. the central fringe will be white
c. the fringe next to the central will be violet
D. there will not be a completely dark fringe
12
762At the first minimum adjacent to the central maximum of a single – slit diffraction pattern, the phase difference
between the Huygen’s wavelet form the edge of the slit and the wavelet from the midpoint of the slit is:
A ( cdot frac{pi}{8} ) radian
B . ( frac{pi}{4} ) radian
12
763A Young’s interference experiment is performed with monochromatic light. The separation between the slits is
( 0.5 m m, ) and the interference pattern on a screen is ( 3.5 m ) away, shows the first
order maximum at ( 3.6 m m ) from the
centre of the pattern. The wavelength is
A ( .515 n m )
B. ( 315 mathrm{mm} )
c. 215 cm
D. ( 15 m )
12
764A light of wavelength ( lambda ) is incident on an object of size b. If a screen is at a
distance D from the object. Identify the correct condition for the observation of
different phenomenon:
a) if ( b^{2}=D lambda ), Fresnel diffraction is
observed
b) if ( b^{2}>>D lambda ), Fraunhoffer diffraction
is observed
c) if ( b^{2}<<D lambda ), Fraunhoffer diffraction
is observed
d) if ( b^{2}=D lambda, ) Fraunhoffer diffraction is
observed
A. a, b and d are true
B. a,c and d are true
( c cdot ) a and c are true
D. a and d are true
12
765What change, if any, is observed in
frequency and wavelength when light travels fro air to glass?
12
766Which of the following undergo
maximum diffraction?
A. ( alpha- )rays
B . ( gamma- ) rays
D. light waves
12
767Two sound sources of sound are placed
along the diameter of a circle of radius
( boldsymbol{R}(boldsymbol{R}>>mathbf{4} boldsymbol{lambda}) ) How many minima will be
heard as one moves along the perimeter
of circle?
( A cdot 16 )
В. 12
( c cdot 4 )
( D )
12
768( A ) is singing a note and at the same
time ( B ) is also singing a note with
1 / 8 the frequency of ( A ). The energies of the two sounds are equal. The disparagement amplitude of the note if
( boldsymbol{B} ) is:
A. same as that of ( A )
B. Twice that of ( A )
c. four times that of ( A )
D. eigth times that of ( A )
12
769How does the angular separation between fringes in single slit diffraction experiment change when the distance of separation between the slit and screen is doubled?12
770Give the essential conditions (any two)
for the source to be Coherent.
(b) In
Young’s double slit experiment, using
monochromatic light of wavelength ( lambda )
the intensity of light at a point on the screen where path difference is I, is ( 2 K ) units. Find out the intensity of light at a point where path difference is ( lambda / 6 )
12
771State Huygen’s principle, Using this principle draw a diagram to show how a plane wave front incident at the interface of the two media gets
refracted when it propagates from a rarer to a denser medium.Hence verify
Snell’s law of refraction
12
772In Young’s double-slit experiment ( boldsymbol{d} / boldsymbol{D}=mathbf{1 0}^{-4}(boldsymbol{d}= ) distance between
slits, ( D= ) distance of screen from the
slits). At point ( P ) on the screen resulting intensity is equal to the intensity due to the individual slit ( boldsymbol{I}_{0} ) Then, the distance of point ( P ) from the central maximum is ( (boldsymbol{lambda}=mathbf{6 0 0 0} boldsymbol{boldsymbol { A }}) )
( mathbf{A} cdot 2 m m )
B. ( 1 mathrm{mm} )
( mathrm{c} .0 .5 mathrm{mm} )
D. ( 4 mathrm{mm} )
12
773A sound source emits two sinusoidal
sound waves. both of wavelength ( lambda )
along paths ( A ) and ( B ) as shown in figure
The sound travelling along path ( B ) is
reflected from five surfaces as shown
and then merges at point ( Q ), producing
minimum intensity at that point. Find
the minimum value of ( d ) in terms of ( lambda )
12
774Which of the following phenomena can be demonstrated by light. But not with sound waves in an air column?
A . Reflection
B. Diffraction
c. Refraction
D. Polarization
12
775The transverse nature of light is shown by
A. interference of light
B. refraction of light
c. polarization of light
D. dispersion of light
12
776A beam of light of wavelength 600 nm from a distance source falls on a single
slit 1 mm wide and a resulting
diffraction pattern is observed on a
screen 2 m away. The distance between
the first dark fringes on either side of central bright fringe is
( mathbf{A} cdot 1.2 mathrm{cm} )
B. ( 1.2 m m )
c. ( 2.4 c m )
D. ( 2.4 m m )
12
777Explain the construction of plane wavefront using Huygen’s principle.12
778A thin sheet of glass ( (mu=1.5) ) of thickness 6 micron introduced in the
path of one of the interfering beams in a double slit experiment shifts the central fringe to a position previously occupied by fifth bright fringe. The the wavelength of light used is
A ( cdot 6000 stackrel{circ}{A} )
в. 3000 ,
( c cdot 4500 stackrel{circ}{A} )
D・7500 ( stackrel{circ}{A} )
12
779If in a Young’s double slit experiment, the slit width is ( 3 mathrm{cm}, ) the separation between slits and screen is ( 70 mathrm{cm} ) and
wavelength of light is ( 1000 mathrm{A} ), then fringe width will be ( (mu=1.5) )
A ( .2 .3 times 10^{-3} mathrm{cm} )
В. ( 2.3 times 10^{-4} m )
( mathbf{c} cdot 2.3 times 10^{-5} mathrm{cm} )
D . ( 2.3 times 10^{-6} mathrm{m} )
12
780Two slits separated by a distance of
1 ( m m ) are illuminated by light of wavelength ( 6.5 times 10^{-7} ) m. Interference
fringes are oberved on a screen placed
at a distance of 1 from the slits.
Calculate the distance between the
third dark fringe and fifth bright fringe.
12
781State whether true or false:
During destructive interference, the crest of one wave meets the trough of the other wave.
A. True
B. False
12
782Two waves are propagating along a taut string that coincides with the ( x ) -axis. The first wave has the wave function
( boldsymbol{y}_{1}=boldsymbol{A} cos [boldsymbol{k}(boldsymbol{x}-boldsymbol{v} boldsymbol{t})] ) and the second
has the wave function ( y_{2}=A cos [k(x+ )
( boldsymbol{v} boldsymbol{t})+boldsymbol{phi}] )
A. For constructive interference at ( x=0, phi=pi )
B. For constructive interference at ( x=0, phi=3 pi )
c. For destructive interference at ( x=0, phi=pi )
D. For destructive interference at ( x=0, phi=2 pi )
12
783State brewsters law.
The value of brewster’s angle for a transparent medium is different for
light of different colours. give reason?
12
784At the centre ( (t=0) ) of Newton’s ring
arrangement, we observe a
A. dark spot
B. bright spot
c. coloured spot
D. None of these
12
785You are provided with a narrow and parallel beam of light. State how you will determine experimentally, whether it is a beam of ordinary(unpolarised) light, partially polarised light or completely polarised light.12
786A ray of light travelling in impure water is incident on a glass plate immersed in
it. When the angle of incidence is ( 51^{circ} ) the reflected ray is totally plane polarized. Given that refractive index of impure water if ( 1.4 . ) The refractive index
of glass should be
( left(tan 51^{circ}=1.235right) )
A . 1.64
в. 1.34
c. 1.53
D. 1.73
12
787Electron microscope, the biggest innovation in microscopy was built on
principle of
A. wave nature of electrons
B. total internal reflection of light
c. thin film optical interference
D. light amplification by stimulated emission of radiation
12
78853. Two polaroids are placed in the path of unpolarized beam
of intensity Isuch that no light is emitted from the second
polaroid. If a third polaroid whose polarization axis makes
an angle with the polarization axis of first polaroid, is
placed between these polaroids then the intensity of light
emerging from the last polaroid will be
(c) (1 cosa 20
(d) 1, cosa e
12
78912. The angle of incidence at which reflected light is totally
polarised for reflection from air to glass (refractive index
n) is
(a) sin (n)
(b) sin-‘ (1/n)
(c) tan-(1/n) (d) tan-‘(n) (AIEEE 2004)
12
790Fill in the blanks with suitable words:
Light has and
nature.
12
791In Young’s double slit experiment with monochromatic source of light of
wavelength ( 6000 A^{circ} ), if the path
difference is ( 1.5 times 10^{-6} m, ) the point
becomes:
A. bright band
B. dark band
c. sometimes bright and sometimes dark
D. data insufficient
12
792A parallel beam of diameter ( d ) is
incident on air-glass interface as shown in figure. The diameter of refracted light
beam is:
( left(boldsymbol{d}=mathbf{3} boldsymbol{m} boldsymbol{m}, boldsymbol{theta}=mathbf{4} mathbf{5}^{mathbf{0}} text { and } frac{boldsymbol{n}_{boldsymbol{g} operatorname{lass}}}{boldsymbol{n}_{boldsymbol{a} i boldsymbol{r}}}=frac{boldsymbol{3}}{boldsymbol{2}}right) )
( A cdot sqrt{12} m m )
В. ( sqrt{14} ) тт
( c cdot sqrt{6} m m )
D. ( 4.5 mathrm{mm} )
12
793Newton postulated his corpuscular theory of light on the basis of
A. Newton’s rings
B. Rectilinear propagation of light
c. colour through thin flims
D. Dispersion of white light into columns
12
794A glass of refractive index 1.5 is coated
with a thin layer of thickness of ( t ) of
refractive index 1.8 light of wavelength
( lambda ) tavelling at the upper and the lower
surfaes of the layer and the two reflected rays interfere. If ( boldsymbol{lambda}=mathbf{6 4 8 n m} )
obtain the least value of ( tleft(operatorname{in} 10^{-8} mright) ) for
which the rays interfere constructively.
12
795In a biprism experiment the distance between the two virtual images of the
slit is ( 0.1 mathrm{cm} ) and the distance between
the slit and screen is ( 1 mathrm{m} ). If the band
width is ( 0.058 mathrm{cm} . ) Calculate the
wavelength of light.
12
796Consider a light beam incident from air to a glass slab at Brewster’s angle as
shown in figure. A polaroid is placed in the path of the emergent ray at point ( mathrm{P} )
and rotated about an axis passing
through the centre and perpendicular to
the plane of the polaroid.
A. For a particular orientation there shall be darkness as observed through the polaroid
B. The intensity of light as seen through the polaroid shall be independent of the rotation
c. The intensity of light as seen through the polaroid shall go through a minimum but not zero for two orientations of the polaroid
D. The intensity of light as seen through the polaroid shall go through a minimum for four orientations of the polaroid.
12
797thickness as shown in figure. One is made pf material ( boldsymbol{A} ) of refractive index
1.5. The other is made of two materials
( B ) and ( C ) with thickness in the ratio 1: 2
The refractive index of ( C ) is ( 1.6 . ) If a
monochromatic parallel beam passing
through the slabs has the same number of wavelengths inside both, the
refractive index of ( boldsymbol{B} ) is
( mathbf{A} cdot 1.1 )
B. 1.2
c. 1.3
D . 1.4.
12
798Fill in the blanks:
According to Newton, different colors of light are due to the difference in of the corpuscles.
A. mass
B. nature
c. shape
D. size
12
799Photoelectric effect supports quantum
nature of light because
This question has multiple correct options
A. there is a maximum frequency of light below which no photoelectrons are emitted
B. the maximum kinetic energy of photoelectrons depends only on the frequency of light and not on its intensity
C. even when the metal surface is faintly illuminated, the photoelectrons leave the surface immediately
D. electric charge of the photoelectrons is quantized
12
800A plane wave front falls on a convex lens
The emergent wave front is :
A. plane
B. cylindrical
c. spherical diverging
D. spherical converging
12
801The polarising angle for glass is:
A. same for different kinds of glass
B. different for different kinds of glass
C. same for lights of all colours
D. varies with time
12
802Find the ( x ) -coordinates on the ( x ) -axis.
(excluding ( boldsymbol{x}=mathbf{0} ) and ( boldsymbol{x}=infty )
This question has multiple correct options
A. ( x=4 lambda )
B . ( x=7 lambda / 4 )
c. ( x=5 lambda / 4 )
D. ( x=3 lambda )
12
803For what distance ray optics a good approximation when the aperture is 4
( mathrm{mm} ) wide and the wavelength is ( 500 n m ? )
A . ( 32 m )
B. ( 69 m )
( c .16 m )
D. ( 8 m )
12
804If in Young’s double slit experiment, the
distance between the two slits is halved
and the distance between the slit and
screen id doubled, then the fringe width will become
A . half
B. double
c. four times
D. unchanged
12
8059. Laser beams are used to measure long distances because
(a) They are monochromatic
(b) They are highly polarised
(c) They are coherent
(d) They have high degree of parallelism
12
806Light travels faster in air than that in glass. This is accordance with
A. wave theory of light
B. corpuscular theory of light
c. neither (a) nor (b)
D. Both (a) and (b)
12
807Light, like sound, cannot pass through vacuum. State whether true or false
A. True
B. False
12
808Which of the following statements
about the behaviour of light is not
correct?
A. Interference patterns are evident for light behaving as rays.
B. Ray properties of light are useful for understanding how images are formed by optical devices such as eyes.
C. Wave properties are important for observing the behaviour of light at a fine scale.
D. Both wave and particle theories of light can be related to the colour sensations produced by light.
12
809The box of a pinhole camera of length ( L ) has a hole of radius a. It is assumed that when the hole is illuminated by a
parallel beam of light of wavelength ( lambda ) the spread of the spot (obtained on the opposite wall of the camera) is the sum of its geometrical spread and the spread due to diffraction. The spot would then have its minimum size say
( boldsymbol{b}_{m i n} ) when:
( ^{mathrm{A}} cdot_{a}=frac{lambda^{2}}{L} ) and ( b_{min }=frac{2 lambda^{2}}{L} )
B. ( a=sqrt{lambda L} ) and ( b_{min }=frac{2 lambda^{2}}{L} )
C ( . a=sqrt{lambda L} ) and ( b_{min }=sqrt{4 lambda L} )
D. ( a=frac{lambda^{2}}{L} ) and ( b_{m i n}=sqrt{4 lambda L} )
12
810If the width of slit is gradually increased, it will be observed experimentally that :
A. bright fringes become reduced in intensity
B. bright fringes become increased in intensity
c. the intensity of minima is strictly zero
D. the fringes become more distinct
12
811Angular width of principal maximum in Fraunhoffer single slit diffraction is 0.1
radian. Angular width of secondary maxima is then
12
812What is not an essential condition for
an observable interference pattern to
occur between the waves two sources?
A. The frequencies of the two sources must be equal
B. The sources must be coherent
c. The sources must emit waves of equal amplitide
D. The waves from the two sources must overlap
12
813In young’s experiment, the fringe width at a distance of ( 50 mathrm{cm} ) from the slits, of
light of wavelength ( 6000 AA ) is ( 0.048 mathrm{cm} ) The fringe width at the same distance for ( lambda=5000 AA ) will be :
A . ( 0.04 mathrm{cm} )
B. ( 0.4 mathrm{cm} )
( c .0 .14 c m )
D. ( 0.45 mathrm{cm} )
12
glass(refractive index 1.5 ) with a thick bottom. It is filled with a liquid of
refractive index ( mu . ) A student finds that,
irrespective of what the incident angle (see figure) is for a beam of light entering the liquid, the light reflected from the liquid glass interface is never completely polarized. For this to happen the minimum value of ( mu ) is :
A ( cdot frac{3}{sqrt{5}} )
в. ( frac{5}{sqrt{3}} )
c. ( sqrt{frac{5}{3}} )
( D )
12
815In Young’s double slit experiment with
sodium vapour lamp of wavelength 589 tun and the slits 0.689 min apart, the
half angular width of the central maximum is
A ( cdot sin ^{-1}(0.01) )
B. ( sin ^{-1}(0.0001) )
c. ( sin ^{-1}(0.001) )
D. ( sin ^{-1}(0.1) )
12
816Visible light of wavelength ( 6000 times )
( 10^{-8} mathrm{cm} ) falls normally on a single slit
and produces a diffraction pattern. It is found that the second diffraction
minimum is at ( 60^{0} ) from the central
maximum. if the first minimum is
produced at ( theta_{1} ) then ( theta_{1} ) is close to :
A ( cdot 25^{circ} )
B. ( 30^{circ} )
( c cdot 20^{0} )
D. ( 45^{circ} )
12
817To demonstrate the phenomenon of interference we require two soruces which emit radiation of
A. nearly the same frequency
B. the same frequency
c. different wavelength
D. the same frequency and having a definite phase relationship.
12
818A plane polarized light is incident normally on the tourmaline plate. Its ( overrightarrow{boldsymbol{E}} )
vectors, make an angle of ( 60^{circ} ) with the
optic axis of the plate. Find the ( % ) difference between initial and final maximum values of ( overrightarrow{boldsymbol{E}} ) vectors.
12
819Ray optics is valid when characteristic dimensions are
A. of the same order as the wavelength of light
B. much smaller than the wavelength of light
c. much larger than the wavelength of light
D. of the order of ( 1 mathrm{mm} )
12
820A parallel beam of light of 500 nm falls on a narrow slit and the resulting diffraction pattern is observed on a screen ( 1 mathrm{m} ) away. It is observed that the first minimum is at a distance of 2.5
( mathrm{mm} ) from the centre of the screen.
Calculate the width of the slit.
12
82121. In Young’s double-slit experiment dID= 104 (d = distan
between slits, D = distance of screen from the slits
At point P on the screen, resulting intensity is equal to the
intensity due to the individual slit Io. Then, the distance of
point P from the central maximum is (a = 6000 Å)
(a) 2 mm
(b) 1 mm
(c) 0.5 mm
(d) 4 mm
12
822si St
2 m
10. Two point sources separated by
2.0 m are radiating in phase with
a = 0.50 m. A detector moves in a
circular path around the two sources
in a plane containing them. How
many maxima are detected?
(a) 16
(b) 20
(c) 24
(d) 32
12
823Light of wave length ( lambda ) air enters into
two medium of refractive indices ( mu ) and
( mu / 2 . ) Two points ( P_{1} ) and ( P_{2} ) lying along the path of this light as shown in the figure. The phase difference between these two point is ( k frac{left(pi mu X_{0}right)}{lambda} . ) Then find
the value of ( mathrm{k} )
( A )
B.
( c .5 )
D.
E. None of thes
12
82450. When an unpolarized light of intensity 1 is incident on a
polarizing sheet, the intensity of the light which does not
get transmitted is
(a) Zero
(b) 10
(C)
40
(c)
-10
12
825A screen is placed ( 2 mathrm{m} ) away from a single narrow slit. The slit width if the first minimum lies ( 5 mathrm{mm} ) on either side
of the central maximum is:
(wave length ( =5000 A^{circ} ) )
A . ( 0.01 mathrm{cm} )
B. ( 0.02 mathrm{cm} )
( c .0 .03 c m )
D. ( 0.04 mathrm{cm} )
12
8268. Microwaves from a transmitter are directed toward a
plane reflector. A detector moves along the normal to the
reflector. Between positions of 14 successive maxima, the
detector travels a distance of 0.14 m. What is the frequency
of transmitter?
(a) 1.5 x100 Hz
(b) 3.0 x100 Hz
(c) 1.5 x100 Hz
(d) 3.0 x10° Hz
TIL.
11
12
827P
u) 2 unit
13. Two coherent narrow slits emitting light of wavelength
2 in the same phase are placed parallel to each other at a
small separation of 32. The light
is collected on a screen S which
is placed at a distance D (>>2)
from the slits. The smallest
distance x such that the P is a
maxima.
(a) √30 gan (b) √80
(c) √50
(d) 75
N
12
828Which theory explains all the characteristics of light?12
829Monochromatic green light of wavelength 550 nm illuminates two parallel narrow slits ( 7.7 mu mathrm{m} ) apart. The
angular deviation ( theta ) of third order (for ( m )
( =3 ) ) bright fringe in radian and in degrees respectively are:
A ( .21 .6,12.4^{circ} )
в. ( 0.216,1.24^{circ} )
c. ( 0.216,12.4^{circ} )
D. ( 216,1.24^{circ} )
12
830A polarizer and an analyzer are oriented so that the maximum amount of lights
is transmitted. Fraction of its
maximum value is the intensity of the
transmitted light reduced when the
analyzer is rotated through (intensity of
incident light ( =boldsymbol{I}_{boldsymbol{o}} boldsymbol{)} )
a) ( 30^{circ} ) b) ( 45^{circ} )
c) ( 60^{circ} )
A ( .0 .375 I_{0}, 0.25 I_{0}, 0.125 I_{0} )
B. ( 0.25 I_{0}, 0.375 I_{0}, 0.125 I_{0} )
C ( cdot 0.125 I_{0}, 0.25 I_{0}, 0.0375 I_{0} )
D. ( 0.125 I_{0}, 0.375 I_{0}, 0.25 I_{0} )
12
831Why don’t we have interference when
two candles are placed close to each other and the intensity is seen at a distant screen? What happens if the
candles are replaced by laser sources?
12
83219. Two beams, A and B. of plane polarized light with
mutually perpendicular planes of polarization are seen
through a polaroid. From the position when the beam A
has maximum intensity (and beam B has zero intensity)
a rotation of polaroid through 300 makes the two beams
appear equally bright. If the initial intensities of the two
beams are 1A and Ig respectively, then I ll, equals
(b) 1/3
(C) 3
(d) 3/2 (JEE Main 2014)
(a)
1
12
833A beam of light containing two wavelengths ( 5200 A ) and ( 6500 A ) is used in Young’s experiment to obtain interference fringes. What is the least distance from the central maximum on
the screen where the bright fringes due to both wavelengths concide? (Given distance between slits is 2 ( mathrm{mm} ) and
distance of screen from slits is 120
( mathrm{mm} )
A. ( 0.156 mathrm{mm} )
B. ( 0.312 mathrm{mm} )
( c .0 .78 mathrm{mm} )
D. ( 1.1 mathrm{mm} )
12
834If ( theta ) is the polarizing angle for a medium
in which the speed of light is ( v ), then according to Brewster’s Law:
( mathbf{A} cdot theta=sin ^{-1}(c / v) )
B ( cdot theta=tan ^{-1}(c / v) )
( mathbf{c} cdot theta=cos ^{-1}(c / v) )
D. ( theta=sin ^{-1}(v / c) )
12
835Resolving power of a telescope
increases with:
A. increase in focal length of eyepiece
B. increase in focal length of objective
C. increase in aperture of eyepiece
D. increase in aperture of objective
12
836The phenomenon of rotation of plane polarized light is called
A. Kerr effect
B. Double refraction
c. optical activity
D. Dichroism
12
837Thin film interference happens with
This question has multiple correct options
A. point or spherical source
B. board source
C. film thickness of the order of 10,000 A
D. very thick transparent slabs
12
838a) Using the phenomenon of polarization, show how transverse nature of light can be demonstrated.
b) Two polaroids ( P_{1} ) and ( P_{2} ) are placed
with their pass axes perpendicular to
each other. Unpolarised light of
intensity ( I_{0} ) is incident on ( P_{1} . ) A third
Polaroid ( P_{3} ) is kept in between ( P_{1} ) and ( P_{2} )
such that its pass axis makes an angle
of ( 30^{circ} ) with that of ( P_{1} ). Determine the intensity of light transmitted through
( P_{1}, P_{2} ) and ( P_{3} )
12
839A beam of light of wavelength 600 nm
from a distant source falls on a single slit ( 1 mathrm{mm} ) wide and the resulting diffraction pattern is observed on a screen ( 2 mathrm{m} ) away. The distance between the first dark fringes on either side of the central bright fringe is?
A . ( 1.2 mathrm{cm} )
B. ( 1.2 mathrm{mm} )
( c .2 .4 mathrm{cm} )
D. ( 2.4 mathrm{mm} )
12
840The maximum intensity in Young’s
double slit experiment is ( I_{0} . ) Distance
between the slits is ( d=5 lambda ), where ( lambda ) is
the wavelength of monochromatic light used in the experiment. What will be the intensity of light in front of one of the
slits on a screen at a distance ( D=10 d )
( ? )
A ( . I_{0} )
в. ( I_{0} / 4 )
c. ( _{overline{4}_{l_{0}}^{I_{0}}} )
D. ( I_{0} / 2 )
12
841In double refraction:
A. the velocity of the E-ray varies with direction
B. e-ray does not obey Snell’s law
C ( . mu ) of E-ray is constant
D. both ( A ) and ( B )
12
8422. Figure shows wavefront P passing through two systems
A and B, and emerging as Q and then as R. The systems
A and B could, respectively, be
(a) a prism and a convergent lens /
(b) a convergent lens and a prism
(c) a divergent lens and a prism
(d) a convergent lens and a
P A
divergent lens
Oі В
12
843Assertion
( (A): ) Microwaves are better carries of signals than optical waves Reason ( (boldsymbol{R}): ) Microwaves move faster than optical waves
A. Both ( A ) and ( R ) are true and ( R ) is correct explanation of ( A )
B. Both ( A ) and ( R ) are true and ( R ) is not the correct explanation of
c. ( A ) is true but ( R ) is false
D. ( A ) is false but ( R ) is true
12
8441: Primary waves can travel in all
directions in an ether
2: Secondary waves can travel only in backward in an ether
A ( . ) 1 is true, 2 is false
B. Both 1 and 2 are true
c. 1 is false, 2 is true
D. Both 1 and 2 are false
12
845Distinguish between interference and diffraction.12
846Wavefront is the locus of all points, where the particles of the medium
vibrate with the same.
A . phase
B. amplitude
c. frequency
D. period
12
847are drawn on light rays to show the direction in which light travels.12
848Explain how an unpolarised light gets polarised when incident on the interface separating the two transparent media.12
849Bichromatic light is used in YDSE
having wavelengths ( lambda_{1}=400 n m ) and
( lambda_{2}=700 n m . ) Find the minimum order
of ( lambda_{1} ) which overlaps with ( lambda_{2} )
12
850a parallel glass slab at a point ( A, ) as
shown in the given figure. It undergoes partial reflection and
refraction. At each reflection ( 25 % ) of
incident energy is reflected. The rays
( A B ) and ( A^{prime} B^{prime} ) undergo interference. The
1 max ratio ( frac{text { nunce is }}{text { : }} ) is ( boldsymbol{I}_{m i} )
( A cdot 4: 1 )
B. 8: 1
c. 7:
29
12
851In Young’s double slit experiment with monochromatic source of light of
wavelength ( 6000 A^{circ}, ) if the path difference at a point on the screen is 6
( times 10^{-6} m ) the number of the bright band
formed at that point is:
( A cdot 2 )
B. 4
( c cdot 6 )
D. 10
12
852In a fresnel’s bi-prism experiment, the
refracting angles of the prism were ( 2.5^{circ} ) and the refracting index of the glass was ( 1.5 . ) With the single slit ( 10 mathrm{cm} ) from the bi-prism ,fringes were formed on a screen ( 1 mathrm{m} ) from the single slit. The fringe width is ( 0.1375 mathrm{mm} ). The wavelength of light is
A. 600 nm
B. 1200 nm
c. ( 60 A^{circ} )
D. 120 A
12
853Calculate the wave number and
frequency of radiation having wavelength ( 5800 lambda )
( left(172400 c m^{-1}, 5.172 times 10^{14} c y operatorname{cles} s^{-1}right) )
12
854If yellow light emitted by sodium lamp in Young’s double slit experiment is replaced by monochromatic blue light of same intensity keeping other parameters constant the new fringe width will :
A. Remain unchanged
B. Increase
c. Decrease
D. Can’t be predicted
12
855In Fraunhofer diffraction pattern, slit
width is ( 0.2 m m ) and screen is at ( 2 m )
away from the lens. If wavelength of light used in ( 5000 A ) then the distance
between the first minimum on either
side of the central maximum is ( (boldsymbol{theta} ) is
A ( cdot 10^{-1} m )
B. ( 10^{-2} ) m
c. ( 2 times 10^{-2} m )
D. ( 2 times 10^{-1} m )
12
856Newton postulated his corpuscular theory of light on the basis of:
A. Newton’s rings.
B. rectilinear propagation of light
c. colour through thin films.
D. Dispersion of white light into colours.
12
857State Brewster’s law of polarisation of light. The polarising angle for a
transparent medium is ( 60^{circ} . ) What will be the refractive index and angle of refraction of the medium?
( tan 60^{circ}=sqrt{3} )
12
858In an experiment, the amplitude of intensity variation of two sources is
focused to be ( 3 % ) of the avg. intensity. Find the ratio of intensity of two interfering sources.
12
859Two coherent point sources ( S_{1} ) and ( S_{2} ) vibrating in phase emit light of wavelength ( lambda ). The separation between the sources is ( 2 lambda ). Consider a line
passing through ( S_{2} ) and perpendicular
to the line ( S_{1} S_{2} ). What is the smallest
distance from ( S_{2} ) where a minimum of
intensity occurs?
12
860Two wave-fronts are emitted from
coherent sources of path difference between them is 2.1 micron. Phase
difference between the wave-fronts at
that point is ( 7.692 pi . ) Wavelength of light emitted by sources will be :
в. 5400 月
c. ( 5460 hat{h} )
D. 5892 月
12
861Distinguish between linearly polarised and unpolarised light.12
86246. Angular width of central maxima in the Fraunhofer
diffraction pattern of a slit is measured. The slit is
illuminated by light of wavelength 6000 A. When the slit
is illuminated by light of another wavelength, the angular
width decreases by 30%. The wavelength of this light will be
(a) 6000 Å
(b) 4200 Å
(c) 3000 Å
(d) 1800 Å
12
863Name the phenomenon which is responsible for bending of light around sharp corners of an obstacle. Under what conditions does this phenomenon take place?12
864Unpolarized red light is incident on the
surface of a lake at incident angle ( boldsymbol{theta}_{boldsymbol{R}} )
An observer seeing the light reflected from the water surface through a polarizer notices that on rotating the polarizer, the intensity of light drops to
zero at a certain orientation. The red
light is replaced by unpolarized blue light. The observer sees the same effect
with reflected blue light at incident
angle ( theta_{s} . ) Then :
A ( cdot theta_{B}<theta_{R}theta_{R}>45^{circ} )
( mathbf{D} cdot theta_{R}>theta_{B}>45^{circ} )
12
865Thin films like soap bubbles and oil
floating on water can create colorful
patterns. Which of the following explanations most accurately describes why this happens?
A. Thin films contain many different colored chemicals
B. Thin films diffract and refract light so that it sets up interference patterns
c. Thin films provide reflection from the front and back surfaces, and this creates interference patterns
D. Thin films polarize light which interferes with the unpolarized light to create colors
E. Thin films absorb some colors and allow others to reflect
12
866varv VC vuuduleury using suurcos Jud
7. Two light waves having the same wavelength 2 in vacuum
are in phase initially. Then the first ray travels a path of
length L, through a medium of refractive index u,. The
second ray travels a path of length L, through a medium of
refractive index Uly. The two waves are then combined to
observe interference effects. The phase difference between
the two, when they interfere, is
27
(a) (L,-1)
14 – My L2)
27
(c) 24 (UsL – 44L)
(a) 2
12
867For which colour is the fringe width minimum?
A . violet
B. red
c. green
D. yellow
12
868If the wavelength of light used is 6000 A. The angular resolution of telescope of objective lens having diameter ( 10 mathrm{cm} ) is rad
A ( cdot 7.52 times 10^{-6} )
в. ( 6.10 times 10^{-6} )
c. ( 6.55 times 10^{-6} )
D. ( 7.32 times 10^{-6} )
12
869Light waves can be polarised because they
A. have high frequencies
B. have short wavelength
c. are transverse
D. can be reflected
12
870Two waves of amplitudes ( A ) and ( 3 A ) are superposed and they have a phase difference of ( 2 pi . ) What kind of
interference is possible
A. constructive interference
B. Destructive interference
c. Interference depends on wavelength difference
D. Interference depends on frequency difference
12
871A slit of width ( a ) is illuminated by white
light. The first minimum for red light ( (lambda )
( =6500 A) ) will fall at ( theta=30^{circ} ) when ( a ) will
be
A ( cdot ) з250 ( stackrel{circ}{A} )
B. ( 6.5 times 10^{-4} )
c. 1.3 micron
D. ( 2.6 times 10^{-4} )
12
872In a Young’s double slit experiment, the
fringes are displaced by a distance ( x ) when a glass plate of refractive index 1.5 is introduced in the path of one of the beams. Then this plate is replaced by another plate of the same thickness, the shift of fringes is ( frac{3}{2} x . ) The refractive index of the second plate is :
A . 2.25
в. 2.0
c. 1.75
D. 1.25
12
873The young’s duble slit experiment is performed with blue and green light of wavelength ( 4360 AA ) and ( 5460 dot{A} )
respectively. if ( x ) is the distance of ( 4 t h ) maxima from central one, then
A. ( x(b l u e)=x(g text { reen }) )
в. ( x(b l u e)>x(text { green }) )
c. ( x(b l u e)<x(text { gree } n) )
D. ( frac{x(b l u e)}{x(g r e e n)}=frac{5460}{4360} )
12
874Microwaves from a transmitter are
directed normally toward a plane reflector. A detector moves along the normal to the reflector. Between
positions of 14 successive maxima the
detector travels a distance 0.14 m. The
frequency of the transmitter is ( (c= ) ( 3 times 10^{8} m s^{-1} )
A. ( 1.5 times 10^{10} mathrm{Hz} )
в. ( 10^{10} mathrm{Hz} )
c. ( 3 times 10^{10} H z )
D. ( 6 times 10^{10} mathrm{Hz} )
12
875Sound waves are passing through two
routes-one in straight path and the other along a semicircular path of
radius ( r ) and are again combined into
one pipe and superposed as shown in
the figure. If the velocity of sound waves
in the pipe is ( v, ) then frequencies of
resultant waves of maximum
amplitude will be integral multiples of:
( A )
в. ( frac{v}{r(pi-1)} )
c. ( frac{2 v}{r(pi-1)} )
D. ( frac{v}{r(pi+1)} )
12
876A wave travelling in air falls on a glass plate, It is partly reflected and partly refracted. The phase difference between
the reflected and refracted waves is
A. zero
в. ( frac{pi}{2} )
( c )
D. ( 2 pi )
12
877The size of corpuscles are for different colours.
A. same
B. different
c. either (a) or (b)
D. None of these
12
878Two stereo speakers are separated by a
distance of ( 2.4 mathrm{m} . ) A person stands at a
distance of ( 3.2 mathrm{m} ) as shown directly in
front of one of the speakers. Find the
frequencies in audible range for which
the listener will hear a minimum sound
intensity:

Speed of the sound in air is ( 320 m s^{-1} )
( mathbf{A} cdot 160(2 n+1) )
B. ( 320(2 n+1) )
( mathbf{c} cdot 200(2 n+1) )
D. ( 100(2 n+1) )

12
879The oil layer on the surface of water appears coloured, due to interference. For this effect to be visible the
thickness of oil layers will be
A . ( 1 m m )
B. ( 1 c m )
c. ( 100 A^{circ} )
D. ( 1000 A^{circ} )
12
880A source ( S ) is kept directly behind the
slit ( S, ) in a double-slit apparatus. Find
the phase difference at a point ( O w h i c h )
is equidistant from ( s 18 ) s2 What will be
the phase difference at ( P ) if a liquid of refraction index ( mu ) is filled. (wavelength
of light in air is / due to the source) ( (lambda<<d, d<>d) )
A. between the screen and the slits
B. between the slits ( & ) the source S. In this case find the minimum distance between the points on the screer where the intensity is half the maximum intensity on the screen
c. Beyond the slits
D. None of these
12
881In a double-slit experiment, the distance between the two slits is 1 m ( m )
and the screen is placed ( 1 m ) away. What
should be the width of each slit to
obtain 20 maxima of double slit pattern
within the central maximum of the
single slit pattern?
A . ( 0.05 mathrm{cm} )
B. ( 0.02 mathrm{cm} )
c. ( 0.01 mathrm{cm} )
D. ( 0.08 mathrm{cm} )
12
882With what type of source of light are cylindrical wave fronts associated?12
883The distance of ( n^{t h} ) bright band on the
screen from the central bright band on either sides of central bright band is
A ( cdot x_{n}=frac{n lambda D}{d} )
B・ ( _{x_{n}}=(2 n-1) frac{lambda D}{d} )
c. ( _{x_{n}}=frac{n lambda d}{D} )
D. ( x_{n}=(2 n-1) frac{lambda D}{2 d} )
12
884Light of wavelength ( 5880 A^{circ} ) is incidents
on a thin glass plate ( (mu=1.5) ) such
that the angle of refraction in the plate is ( 60^{0} ). The minimum thickness of the
plate, so that it appears dark in the reflected light will be
A ( .3920 A^{circ} )
( ^{circ} )
B. ( 4372 A^{circ} )
( c .5840 A^{circ} )
D. ( 6312 A^{circ} )
12
885The maximum number of possible interference maxima for slit separation equal to twice the wavelength in Young’s double slit experiment is :
A . infinite
B. five
c. three
D. zero
12
886An unpolarised beam of intensity ( boldsymbol{I}_{mathbf{0}} )
falls on a polaroid at an angle of ( 45^{0} . ) The intensity of the emergent light is
A ( cdot frac{I_{0}}{2} )
в. ( I_{0} )
c. ( frac{I_{0}}{4} )
D. zero
12
887In a modified ( Y D S ) the two slits ( S_{3} ) and
( S_{4} ) are placed in front of the slits ( S_{1} ) and
( S_{2}, ) calculate the ratio of ( m a x^{m} )
intensity to minimum intensity produced in the screen if
12
888Consider the arrangement shown in figure (17-E4). The distance ( D ) is large compared to the separation ( d ) between
the slits
(a) Find the minimum value of
( d ) so that there is a dark fringe at ( O .(b) )
Suppose ( d ) has this value. Find the
distance ( x ) at which the bright fringe is formed.
(c) Find the fringe-width.
12
88914. Due to interference
L P
Screen
between direct and
reflected light from
mirror, maxima is
Mirror
formed at point P.
By what minimum
distance mirror is shifted downward to find minima at
point P. (Assume that, wavelength of light is 600 mm)
(a) 100 nm
(b) 200 nm
(c) 300 nm
(d) 400 nm
12
890A thin slice is cut out of a glass cylinder along a plane parallel to its axis. The slice is placed on a flat glass plae as shown in figure. The observed interference fringes from this combination shall be
A. straight
B. circular
c. equally spaced
D. having fringe spacing which increases as we go outward
12
891Figure shows two coherent sources ( S_{1} )
and ( S_{2} ) emitting wavelength ( lambda ). The
separation ( S_{1} S_{2}=1.5 lambda ) and ( S_{1} ) is
ahead in phase by ( pi / 2 ) relative ( S_{2} ). Then the maxima occur in direction ( theta ) given
by ( sin ^{-1} ) of
( (i) 0 ;(i i) 1 / 2 ;(i i i)-1 / 6 ;(i v)-5 / 6 )
Correct options are:
A. ( (i i),(i i i),(i v) )
B. (i),( ( (i i),(i i i) )
c. ( (i),(i i i),(i v) )
D. all of the above
12
892When the angle of incidence on a
material is ( 60^{circ} ), the reflected light is
completely polarised. The velocity of the refracted ray inside the material is
A . ( 3 times 10^{8} )
B. ( frac{3}{sqrt{2}} times 10^{8} )
c. ( sqrt{3} times 10^{8} )
D. ( 0.5 times 10^{8} )
12
89361. A plane wave of monochromatic light falls normally
on a uniform thin film of oil which covers a glass plate.
The wavelength of source can be varied continuously.
Complete destructive interference is observed for
a = 5000 Å and 1 = 1000 Å and for no other wavelength
in between. If u of oil is 1.3 and that of glass is 1.5, the
thickness of the film will be
(a) 6.738 x10 cm (b) 5.7 x 10 cm
(c) 4 x 10 cm
(d) 2.8 x 10 cm
12
894Amplitudes of two light waves of the
same frequency are in the ratio 4: 3
What will be the ratio of maximum and
minimum intensities if the two wave
interfere?
12
895Match the following:
Column I
A. ( mu=tan i_{p} )
P. Snell’s law
B. ( mu=frac{1}{sin i_{c}} )
Q. Brewster’s law
C. ( mu=frac{sin i}{sin r} )
R. Prism
D. ( mu= )
( frac{sin left(frac{A+D_{m}}{2}right)}{sin frac{A}{2}} begin{array}{l}text { S. Total internal } \ text { reflection }end{array} )
12
896What is the shape of the wavefront in each of the following cases:
(a) Light diverging from a point source.
(b) Light emerging out of a convex lens when a point source is placed at its focus.(c) The portion of the wavefront of light from a distant star intercepted by
the Earth.
12
897A light wave can travel
This question has multiple correct options
A. In vacuum
B. In vacuum only
C . In a material medium
D. In a material medium only
12
898The condition for constructive
interference is path difference should
be equal to :
A. odd integral multiple of wavelength
B. Integral multiple of wavelength
c. odd integral multiple of half wavelength
D. Integral multiple of half wavelength
12
899Light is incident at an angle ( phi ) with the
normal to a plane containing two slits of
separation ( d . ) Select the expression that
correctly describes the positions of the
interference maxima in terms of the
incoming angle ( phi ) and outgoing angle ( theta )
( ^{mathbf{A}} cdot sin phi+sin theta=left(m+frac{1}{2}right) frac{lambda}{d} )
( mathbf{B} cdot d sin theta=m lambda )
( mathrm{c} cdot sin phi-sin theta=(m+1) frac{lambda}{d} )
” ( sin phi+sin theta=m frac{lambda}{d} )
12
900In a biprism experiment, the distance of 20 th bright bandfrom the center of the
interference pattern is ( 8 mathrm{mm} . ) The distance of 30 th bright band from the center is
A . ( 11.8 mathrm{mm} )
B. 12mm
c. ( 14 mathrm{mm} )
D. ( 16 mathrm{mm} )
12
901The intensity of the central maximum in Youngs double-slit experiment is ( 4 I ) The intensity at the first minimum is zero and the distance between two
consecutive maxima is ( boldsymbol{w} ). The distance
from the central maximum to the
position where the intensity falls to ( I ) is
A ( frac{2}{3} omega )
в. ( frac{1}{4} omega )
c. ( frac{1}{2} omega )
D. ( frac{1}{3} )
12
902In Young’s double slit experiment, the
two slits act as coherent sources of
equal amplitude ‘a’ and of wavelength ( lambda )
In another experiment with the same
set up, the two slits are sources of equal
amplitude ‘a’ and wavelength ( lambda ), but
have ( 90^{circ} ) phase difference. The ratio of intensity of light at the midpoint of the screen in the first case to that in the
second case is
( mathbf{A} cdot 2: 1 )
B. 1: 2
c. 3: 4
D. 4: 3
12
903A ray of light from denser medium strikes a rarer medium at an angle of
incidence i. The reflected and refracted
rays make an angle of ( 90^{circ} ) with each other. Angle of reflection and refraction
are r ( & r^{1} . ) The critical angle is
a) ( sin ^{-1}(tan r) )
b) ( sin ^{-1}(cot r) )
c) ( sin ^{-1}left(tan r^{1}right) )
d) ( sin ^{-1}left(cot r^{1}right) )
A. only a is correct
B. only b is correct
c. a and b are correct
D. a and d are correct
12
904Determine the width of the region where the fringes will be visible
( A cdot 4 c m )
B. ( 6 mathrm{cm} )
( c .2 c m )
D. 3 cm
12
905The thinnest bubble film in air that can
possibly strongly reflect red light
because of constructive interference
makes up a certain bubble. How could we create the thinnest
bubble film that will strongly reflect
purple light?
A. Use a thicker film than the film used for the “red” bubble
B. Use a film with a higher index of refraction than the film used for the “red” bubble
C. Make a bubble larger than the “red” bubble
D. Make a bubble smaller than the “red” bubble
E. Use a thinner film than the film used for the “red” bubble
12
906Huygen’s originally thought that for the propagation of light waves wavefront is required.
A. True
B. False
12
907The wave nature of the electron was
verified using
A. Photo electric effect
B. Compton effect
c. The phenomenon of X-ray emission
D. Diffraction of electron by a crystal
12
908Use the mirror equation to show that an object placed between ( f ) and ( 2 f ) of ( a )
concave mirror produces a real image beyond ( 2 f )
OR
Find an expression for intensity of transmitted light when a polaroid sheet is rotated between two crossed
polaroids. In which position of the polaroid sheet will the transmitted intensity be maximum?
12
909At the angle of polarisation, the angle of inclination between the reflected and
refracted rays is
( A cdot frac{pi}{8} )
в. ( frac{pi}{6} )
( c cdot frac{pi}{4} )
0.5
12
910How will you identify with the help of an experiment whether a given beam of light is of polarized light or of unplolarised light?12
911slit separation dis ( 0.3 mathrm{mm} ) and the
screen distance D is 1 m. A paralle
beam of light of wavelength 600 nm is
incident on the slits at angle ( alpha ) as
shown in figure. On the screen, the point O is equidistant from the slits and
distance PO is ( 11.0 mathrm{mm} ). Which of the
following statement (s) is/are correct?
A. For ( alpha=0 ), there will be constructive interference at
point P.
B. For ( alpha=frac{0.36}{pi} ) degree, there will be destructive
interference at point P.
C ( cdot_{text {Fro } alpha}=frac{0.36}{pi} ) degree, there will be destructive
interference at point 0
D. Fringe spacing depends
12
912If the incidence is at polarising angle,
the angle between Reflected ray and the
Refracted ray from a surface is
12
913A travelling acoustic wave frequency
( 500 H z ) is moving along the positive ( x )
direction with a velocity of ( 300 m s^{-1} )
The phase difference between two
points ( x_{1} ) and ( x_{2} ) is ( 60^{circ} . ) Then the minimum separation between the two
points is:
( mathbf{A} cdot 1 m m )
в. ( 1 mathrm{cm} )
( c cdot 10 mathrm{cm} )
D. ( 10 mathrm{mm} )
12
914incident on a coated glass plate. If ( 25 % ) of the incident light is reflected from
the upper surface and ( 50 % ) of light is
reflected from the lower surface of the
glass plate, the ratio of maximum to
minimum intensity in the interference
region of the reflected light is
( A )
B.
( c cdot frac{5}{8} )
( D cdot 8 )
( overline{5} )
12
915Unpolarized light of intensity ( I ) is incident on a system of two polarizes, ( A )
followed by ( B ). The intensity of emergent light is ( I / 2 . ) If a third polarizer ( C ) is placed between ( A ) and ( B ), the intensity
of emergent light is reduced to ( I / 3 . ) The
angle between the polarizers ( A ) and ( C ) is
( theta . ) Then
( ^{mathrm{A}} cdot cos theta=left(frac{2}{3}right)^{1 / 4} )
в. ( cos theta=left(frac{1}{3}right)^{1 / 4} )
( ^{mathrm{c}} cos theta=left(frac{1}{3}right)^{1 / 2} )
Des ( theta=left(frac{2}{3}right)^{1 / 2} )
12
916The y-coordinate of second order bright
(maxima) formed on the screen is
A ( .250 mu m )
B. ( 500 mu m )
( mathbf{c} .-250 mu m )
( mathbf{D} cdot-500 mu m )
12
917Light travels as a
A. parallel beam in each medium
B. convergent beam in each medium
C. divergent beam in each medium
D. divergent beam in one medium and convergent beam in the other medium
12
918In Young’s double-slit experiment the
spacing between the slits is ‘d and wavelength of light used is 6000 A. If the angular width of a fringe formed on a
distant screen is ( 1^{0}, ) then value ( ^{prime} d^{prime} ) is :
A . ( 1 m m )
B. ( 0.05 mathrm{mm} )
c. ( 0.03 m m )
D. ( 0.01 m m )
12
919The parallel rays of white light are made an incident normally on an air film of uniform thickness. 250 fringes are seen in the transmitted light between
( 4000 A^{circ} ) and ( 6500 A^{circ} . ) Thickness of air
film is
A . ( 1.3 m m )
в. ( 1.5 mathrm{mm} )
c. ( 0.13 m m )
D. ( 0.11 m m )
12
920The refractive index of a certain flint
glass is ( 1.65 . ) Incident angle is the light reflected from the surface of the glass
completely polarized if the glass is immersed in (a) air and (b) water is
( left(tan 58.8^{circ}=1.65right)left(tan 51.1^{circ}=1.24right) )
A. ( 60^{circ}, 50^{circ} )
B. 58.8′, 51.1 ( ^{circ} )
( c cdot 65^{circ}, 52^{circ} )
D. ( 61^{circ}, 54^{circ} )
12
921The intensity of sound reduces by ( 20 % ) on passing through a glass slab. If sound of intensity 1 is made to cross through two such slabs, then the
intensity of emergent sound will be
A. 36 %
B. 64%
c. ( 40 % )
D. 80%
12
922The phase difference between two waves from successive half period
zones or strips is :
A ( cdot frac{pi}{4} )
в. ( frac{pi}{2} )
( c . pi )
D. zero
12
923When two waves of almost equal
frequency ( n_{1} ) and ( n_{2} ) are produced simultaneously, then the times interval between successive maxima is
A ( cdot frac{1}{n_{1}+n_{2}} )
в. ( frac{1}{n_{1}}+frac{1}{n_{2}} )
c. ( frac{1}{n_{1}}-frac{1}{n_{2}} )
D. ( frac{1}{n_{1}-n_{2}} )
12
924Two independent monochromatic
sodium lamps can not produce interference because
A. The frequencies of the two sources are different
B. The phase difference between the two sources changes will respect to time.
c. The two sources become coherent.
D. The amplitude of two sources is different
12
925Two coherent light sources ( S_{1} ) and ( boldsymbol{S}_{2}(boldsymbol{lambda}=mathbf{6 0 0 0} boldsymbol{A}) ) are 1 mm apart from
each other. The screen is placed at a distance of ( 25 mathrm{cm} ) from the sources. The width of the fringes on the screen
should be
A. ( 0.015 mathrm{cm} )
В. ( 0.013 mathrm{cm} )
c. ( 0.01 mathrm{cm} )
D. ( 0.10 mathrm{cm} )
12
926The width of one of the two slits in
Young’s double slit experiment is double of the other slit. Assuming that the amplitude of the light coming from a slit is proportional to the slit width. Find the ratio of the maximum to the
minimum intensity in the interference
pattern
12
927At what maximum width ( delta_{max }, ) of the
slit are the interference fringes on the
screen observed still sharp?
( mathbf{A} cdot 42 mu m )
B. ( 36 mu m )
( mathrm{c} .64 mu mathrm{m} )
D. none of these
12
928Bartholinus discovered:
A. Interference by splitting the wave front
B. Polarisation by reflection
C. Polarisation by refraction
D. Polarisation by double refraction
12
929Who first proposed that the light exhibits wave nature and explained wave phenomenon?
A. Max Planck
B. James Clerk Maxwell
c. Isaac Newton
D. Christian Huygens
12
930The bending of light about corners of an obstacle is called:
A. Dispersion
B. Refraction
c. Deviation
D. Diffraction
12
931Let a beam of wavelength ( lambda ) fall on
parallel reflecting planes with
separation ( d ), then the angle ( theta ) that the
beam should make with the planes so that reflected beams from successive
planes may interfere constructive
should be (where, ( boldsymbol{n}=mathbf{1}, mathbf{2}, dots . .) )
( ^{text {A }} cdot cos ^{-1}left(frac{n lambda}{2 d}right) )
B ( cdot sin ^{-1}left(frac{n lambda}{2 d}right) )
( ^{mathbf{c}} cdot sin ^{-1}left(frac{n lambda}{d}right) )
D. ( tan ^{-1}left(frac{n lambda}{d}right) )
12
932The waveforms of a light wave traveling
in vacuum are given by ( boldsymbol{x}+boldsymbol{y}+boldsymbol{z}=boldsymbol{c} )
The angle made by the direction of propagation of light with the ( X ) -axis is
A ( cdot 0^{circ} )
B ( cdot 45^{circ} )
( c cdot 90^{circ} )
D. ( cos ^{-1} frac{1}{sqrt{3}} )
12
933State clearly how an unpolarised light gets linearly polarised when passed through a polaroid.
(i) Unpolarised light of intensity ( I_{0} ) is
incident on a polaroid ( P_{1} ) which is kept
near another polaroid ( P_{2} ) whose pass
axis is parallel to that of ( boldsymbol{P}_{1} ). How will the
intensities of light, ( boldsymbol{I}_{1} ) and ( boldsymbol{I}_{2} )
transmitted by the polaroids ( P_{1} ) and ( P_{2} )
respectively, change on rotating ( boldsymbol{P}_{1} )
without disturbing ( P_{2} ? )
(ii) Write the relation between the
intensities ( I_{2} ) and ( I_{1} )
12
934Unpolarised light of intensity I passes through an ideal polarizer A. Another identical polarizer B is placed behind A. The intensity of light beyond B is found to be ( frac{1}{2} . ) Now another identical polarizer ( mathrm{C} ) is placed between ( mathrm{A} ) and ( mathrm{B} ). The intensity beyond B is now found to be ( frac{1}{8} ) The angle between polarizer A and C is?
A ( cdot 45^{circ} )
B. ( 60^{circ} )
( c cdot 0^{circ} )
D. ( 30^{circ} )
12
935To reduce the light reflected by the glass surface of a camera lens, the surface is
coated with a thin layer of another material which has an index of
refraction ( (mu=7 / 4) ) smaller than that of glass. The least thickness of the layer to ensure that light falling
perpendicularly on the surface and
having wavelengths, ( lambda_{1}=700 mathrm{nm} ) and ( lambda_{2} )
( =420 mathrm{nm} ) will be weekly reflected for
both wavelengths is ( 10^{-7} mathrm{m} ). Find ( x ) ?
12
936The path difference produced by two
waves is ( 3.75 mu m ) and the wavelength is ( mathbf{5 0 0 0} boldsymbol{A} . ) The point is
A. Uncertain
B. Dark
c. Partially bright
D. Bright
12
937State any one difference between
interference of light and diffraction of
light.
12
938In a single slit diffraction with ( lambda= ) ( 500 n m ) and a lens of diameter ( 0.1 mathrm{mm} )
width of central maxima, obtain on
screen at a distance of ( 1 mathrm{m} ) will be
( mathbf{A} cdot 5 m m )
B. ( 1 mathrm{mm} )
( mathrm{c} .10 mathrm{mm} )
D. ( 2.5 m m )
12
93971. In Young’s double-slit experiment using monochroma
light, the light pattern shifts by a certain distans
the screen when a mica sheet of refractive indexu
thickness t microns is introduced in the path of one of the
interfering waves. The mica sheet is then removed and
the distance between the plane of slits and the screen i
doubled. It is found that the distance between successive
maxima (or minima) now is the same as the observed
fringe shift upon the introduction of the mica sheet
Calculate the wavelength of light?
(a) (1/2)t (u – 1)
(b) t (u – 1)
(c) ut
(d) 3ut
12
940Unpolarized light of intensity ( boldsymbol{I}_{mathbf{0}} ) is incident on a polarizer and the emerging light strikes a second polarizing filter with its axis at
( 45^{circ} ) to that of the first. The intensity of
the emerging beam:
A ( cdot frac{I o}{2} )
в. ( frac{text { Io }}{4} )
( c cdot I_{o} )
D. ( frac{text { Io }}{3} )
12
941The angle of incidence at which reflected light is totally polarised for reflection from air to glass (refractive index ( n ) ) is
A ( cdot sin ^{-1}(n) )
B. ( sin ^{-1}left(frac{1}{n}right) )
( ^{mathbf{c}} cdot tan ^{-1}left(frac{1}{n}right) )
( mathbf{D} cdot tan ^{-1}(n) )
12
942Assertion
Diffraction takes place for all types of
waves mechanical or non-mechanical,
transverse or longitudinal.
Reason
Diffraction’s effect are perceptible only if wavelength of wave is comparable to dimensions of diffracting device.
A. Both Assertion are not correct and Reason is the correct
B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
C. Assertion is correct but Reason is incorrect;Reason is not correct explanation for Assertion
D. Both Assertion is correct and Reason are incorrect
12
943Assertion: The clouds in sky generally appear to be whitish.

Reason: Diffraction due to clouds is
efficient in equal measure at all wavelengths.
A. If both assertion and reason are true but the reason is the correct explanation of assertion
B. If both assertion and reason are true but the reason is not the correct explanation of assertion
c. If assertion is true but reason is false
D. If both the assertion and reason are false
E. If reason is true but assertion is false

12
944A microscope is used with sodium light and its resolving power is not sufficiently large.Higher resolution will
be obtained by using wavelength of
A. 20 micron
B. 2 micron
c. 1 micron
D. ( 400 mathrm{A}^{circ} )
12
945Indentify the correct statement from the
following
This question has multiple correct options
A. Wave nature of light was proposed by Huygen.
B. The direction of light ray and its wave front are opposite.
C. Huygen’s wave theory could not explain phenomenon of reflection.
D. A monochromatic ray of light after passing through the prism should be made of one colour only.
12
946In a diffraction(single slit experiment), the slit is exposed by white light. The fringe surrounding the central fringe is
A. Red
B. Yellow
c. violet
D. Green
12
947To ensure almost 100 per cent
transmittivity, photographic lenses are often coated with a thin layer of dielectric material. The refractive index
of this material is intermediated between that of air and glass (which makes the optical element of the lens)
A typically used dielectric film is ( M g F_{2} ) ( (n=1.38) . ) What should the thickness of the film be so that at the center of the
visible spectrum ( (5500 A) ) there is maximum transmission.
A ( cdot 5000 ) a
в. 2000 А
c. 1000 a
D. 3000 ,
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948When waves of same intensity from two coherent sources reach a point with
zero path different the resulting intensity is ( mathrm{K} ). When the above path difference is ( lambda / 4 ) the intensity becomes
( A cdot K )
B. K/2
( c cdot k / 4 )
D. K/8
12
949When an unpolarised light is polarized, then the intensity of light of the polarized wave :
A. remains the same
B. gets doubled
c. gets halved
D. depends on the colour of the light.
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