# Dual Nature Of Radiation And Matter Questions

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

Question NoQuestionsClass
1In Millikan’s oil drop experiment an oil drop of radius ( r ) and charge ( Q ) is held in equilibrium between the plates of a charged parallel plate ‘capacitor when
the potential difference is ( V . ) To keep a
drop of radius ( 2 r ) and with a charge ( 2 Q )
in equilibrium between the plates, the potential difference required will be :
A . ( 8 V )
в. ( 4 V )
( c .2 V )
D. ( 1 V )
12
2Which of the following shows particle nature of light ?
A. Refraction
B. Interference
c. Polarization
D. Photoelectric effect
12
3Let ( n_{r} ) and ( n_{b} ) be respectively the number of photons emitted by a red bulb and a blue bulb of equal power in a given time, then:
A ( cdot n_{r}=n_{b} )
в. ( n_{r}n_{b} )
D. data insufficient
12
4If the ( K E ) of a free electron doubles then
its de-Broglie wavelength changes by a
factor
A ( cdot frac{1}{2} )
в. ( frac{1}{sqrt{2}} )
( c cdot 2 )
D. ( sqrt{2} )
12
5An electron is confined in the region of
width ( 1 A^{circ} ). Estimate its K.E.
A. 3.4 ev
B. 3.8 ev
c. 13.6 ev
D. 10.2 ev
12
6An electric field can just support a
water droplet ( 1.0 times 10^{-6} mathrm{m} ) in diameter
carrying one electron charge. The magnitude of electric field strength is
A ( cdot 3.21 times 10^{4} V / m )
В. ( 2.31 times 10^{4} V / m )
C ( .1 .32 times 10^{4} V / m )
D. ( 6.42 times 10^{4} V / m )
12
7The stopping potential in an experiment
of photon is ( 2 mathrm{eV} ). What is the maximum
kinetic energy of photoelectrons emitted ?
12
835. In Q. 32, if the cathode and the anode are kept at the same
potential, the emitted electrons have
(a) the same KE equal to 1.36 eV
(b) the average KE equal to (1.36/2) eV
(c) the maximum KE equal to 1.36 eV
(d) the minimum KE equal to 1.36 eV
12
9The work function of a certain metal is
( 3.31 times 10^{-19} J . ) Then, the maximum
kinetic energy of photoelectrons emitted by incident radiation of wavelength 5000 A is ( left(G i v e n h=6.62 times 10^{-34} J-s, c=right. )
( left.mathbf{3} times mathbf{1 0}^{-mathbf{8}} mathbf{m} s^{-1}, boldsymbol{e}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} boldsymbol{C}right) )
A ( .248 e V )
B. ( 0.41 e V )
c. ( 2.07 e V )
D. ( 0.82 e V )
12
10In which of the following transition will the wavelength be minimum?
A ( . n=6 ) to ( n=4 )
в. ( n=4 ) to ( n=2 )
c. ( n=3 ) to ( n=1 )
D. ( n=2 ) to ( n=1 )
12
11If we assume kinetic energy of a proton is equal to energy of the photon, the ratio of de Broglie wave length of proton to photon is proportional to:
A. ( E )
( mathbf{B} cdot E^{-1 / 2} )
( c cdot E^{1 / 2} )
D. ( E^{3 / 2} )
12
12The minimum energy required to dissociate ( A g B r ) bond in ( 0.6 e V . A )
photographic flim is coated with a sliver bromide layer. Find the maximum
wavelength whose signature can be
recorded on the film
A. ( 207 n m )
в. 702 ( n m )
c. 207 ( A^{circ} )
D. 2070 ( n m )
12
13In photoelectric effect, the photocurrent
A. depends both on intensity and frequency of the incident light.
B. does not depend on the frequency of incident light but depends on the intensity of the incident light.
C. decreases with increase in frequency of incident light.
D. increases with increase in frequency of incident light.
12
14A charged drop of radius ( 1.92 mathrm{mm} ) is kept stationary by the application of an electric field of ( 1.65 times 10^{6} mathrm{N} / mathrm{C} ) in
Millikans oil drop experiment. The charge, if the density of oil is 920 ( K g / m^{3}, ) is
A ( cdot 1.72 times 10^{-18} )
В. ( 16.2 times 10^{-19} )
c. ( 1.82 times 10^{-17} )
D. ( 1.92 times 10^{-17} )
12
15The wavelength associated with an electron having kinetic energy is given by the expression:
( mathbf{A} cdot h / sqrt{2 m E} )
в. ( 2 h / m E )
c. ( 2 m h E )
D. ( frac{2 sqrt{2 m E}}{h} )
12
16Write down de Broglie’s relation and explain the terms therein.12
17A body of mass ( x k g ) is moving with
velocity of ( 100 m ) sec ( ^{-1} ). Its de Broglie wavelength is ( 6.62 times 10^{-35} ) m. Hence ( x )
is:
( left[boldsymbol{h}=mathbf{6 . 6 2} times mathbf{1 0}^{-mathbf{3 4}} boldsymbol{J}-boldsymbol{s e c}right] )
A. ( 0.25 k g )
B. ( 0.15 k g )
c. ( 0.2 k g )
D. ( 0.1 k g )
12
18U
db
15. In an experiment, electrons are
made to pass through a narrow
slit of width d comparable to
their de Broglie wavelengths.
They are detected on a screen
at a distance D from the slit
(see the figure). Which of the following graphs can be
expected to represent the number of electrons N detected
as a function of the detector position y(y = 0 corresponds
to the middle of the slit)?
у
(a)N
+
(b) N 47-
(C)N+
f
d
(d) NA
12
19Ultra – violet rays are detected by:
A. Fluoroscence
B. Thermopile
C. Thermo – couple
D. Thermometer
12
20If Bohr radius is ( r_{0}, ) the corresponding de Broglie wavelength of the electron is
( ^{mathbf{A}} cdotleft(frac{2 pi}{r_{o}}right) )
В ( cdotleft(frac{r_{o}}{2 pi}right) )
c. ( left(frac{1}{2 pi r_{o}}right) )
D. ( 2 pi r_{o} )
12
21In an experiment of photoelectric effect,
the graph of maximum kinetic energy
( E_{k} ) of the emitted photoelectrons versus
the frequency v of the incident light is a
straight line ( A B ) as shown in Figure
below:
(i) Threshold frequency of the metal.
(ii) Work function of the metal.
(iii) Stopping potential for the photoelectrons emitted by the light of
frequency ( boldsymbol{v}=mathbf{3 0 x} times mathbf{1 0}^{mathbf{1 4}} mathbf{H z} )
12
22If in Millikan’s oil drop experiment charges on drops are found to be
( 8 mu C, 12 mu C, 20 mu C, ) then quanta of quanta of charge is :-
( A cdot 8 mu C )
в. ( 4 mu C C )
c. ( 20 mu C )
D. ( 12 mu C )
12
23A photoelectric cell is lightened by a light source, situated at a distance ( d ) from the cell. If distance becomes ( boldsymbol{d} / mathbf{2} )
then number of electrons emitted per sec will be:-
A. Remains same
B. Four times
c. Two times
D. One fourth
12
24cathode plate inside a vacuum tube as
shown in the figure. The work function
of the cathode surface is ( phi ) and the
anode is a wire mesh of conducting
material kept at a distance d from the
cathode. A potential difference V is
maintained between the electrodes. If
the minimum de Broglie wavelength of
the electrons passing through the
anode is ( lambda_{e}, ) which of the following
statement(s) is(are) true?
A ( cdot lambda_{e} ) increases at the same rate as ( lambda_{p h} ) for ( lambda_{p h}>phi / e) lambda_{e} ) is
pproximately halved if ( V ) is made four time
12
25If the wavelength of particle of momentum ( P ) is equal to ( lambda ), then what
will be its wavelength for momentum
( mathbf{1 . 5 P ?} )
A ( cdot frac{2}{3} lambda )
в. ( frac{4}{3} lambda )
c. ( frac{3}{2} )
D. ( lambda )
12
26What should be the minimum work
function of a metal so that visible light
is able to cause emission?
(visible light=400-700 ( n m ) )
A .1 .77 eV
B. 1.87 ( e V )
c. 1.97 eV
D. None of these
12
27Light of two different frequencies whose photons have energies leV and ( 2.5 mathrm{eV} ) successively illuminate a metal of work
function 0.5 eV.The ratio of the
maximum speeds of the emitted
electrons will he
A .1: 5
B. 1: 4
( c cdot 1: 2 )
D. 1:
12
2865. A 60 W bulb is placed at a distance of 4 m from you. The
bulb is emitting light of wavelength 600 nm uniformly in
all directions. In 0.1 s, how many photons enter your eye
if the pupil of the eye is having a diameter of 2 mm?
[Take hc = 1240 eV-nm]
(a) 2.84 x 1012
(b) 2.84 x 1011
(c) 9.37 x 10″ (d) 6.48 x 1011
12
29Monochromatic light of wave length ( 667 mathrm{nm} ) is produced by a helium neon laser. The power emitted is ( 9 mathrm{mW} ). The
number of photons arriving per second on the average at a target irradiated by this beam is
A ( cdot 3 times 10^{16} )
В . ( 3 times 10^{19} )
( mathrm{c} cdot 9 times 10^{15} )
D. ( 9 times 10^{17} )
12
30S
16. The surface of a metal is illuminated with a light of
wavelength 400 nm. The kinetic energy of the ejected
photoelectrons was found to be 1.68 eV. The work
function of the metal is (hc = 1240 eV nm)
(a) 3.09 eV
(b) 1.41 eV
(c) 151 eV
(d) 1.68 eV (AIEEE 2009)
12
31The kinetic energy of an electron get tripled then the de-Broglie wavelength associated with electron changes by a
factor of
A ( cdot frac{1}{3} )
B. ( sqrt{3} )
c. ( frac{1}{sqrt{3}} )
D. 3
12
32The energy of a ( K ) -electron in tungsten is ( -20 k e V ) and of an ( L ) -electrons is
( -2 k e V . ) The wavelength of ( X ) -rays emitted when there is electronjump from ( boldsymbol{L} ) to ( boldsymbol{K} ) shell:
A ( .0 .3443 AA )
в. ( 0.6887 AA )
c. ( 1.3982 dot{A} )
D. 2.78 音
12
33If the shortest wavelength of the continuous X-ray spectrum coming out of a Coolidge tube is ( 0.01 n m ), then the de Broglie wavelength of the electron reaching the target metal in the Coolidge tube is approximately ( left(h c=12400 e V A, h=6.63 times 10^{-34} ) in right.
MKS, mass of electron= ( 9.1 times )
( left.10^{-31} k gright) )
A . 0.35
в. 0.035
( c .35 )
D. 1350
12
34The threshold frequency for a
photosensitive metal is ( 3.3 times 10^{14} H z . ) If
light of frequency ( 8.2 times 10^{14} H z ) is
incident on this metal, the
cutoff voltage for the photoelectric emission is nearly:
A . ( 1 v )
B. 2V
c. ( 3 v )
D. ( 5 v )
12
35Define the term work function of a
metal.
12
36Assertion
There is a physical significance of
matter waves.
Reason
Both interference and diffraction occurs
in it.
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. Both Assertion and Reason are incorrect.
12
3717. If the momentum of an electron is changed by Ap, then
the de-Broglie wavelength associated with it changes by
0.50%. The initial momentum of the electron will be
4
(a)
(6)
Ap
200
(c) 1994p
199
(d) 400 Ap
12
38Work function of sodium is ( 2.3 e V ). Does
sodium show photo-electric emission for light wavelength 6800 A?
12
39A proton and an electron initially at rest are accelerated by the same potential difference. Assuming that a proton is 2000 times heavier than an electron, what will be the relation between the de
Broglie wavelength of the proton ( left(boldsymbol{lambda}_{boldsymbol{p}}right) )
and that of electron ( left(boldsymbol{lambda}_{e}right) ) ?
A ( cdot lambda_{p}=2000 lambda_{e} )
B. ( lambda_{p}=frac{lambda_{e}}{2000} )
c. ( lambda_{p}=20 sqrt{5 lambda_{e}} )
D. ( lambda_{p}=frac{lambda_{e}}{20 sqrt{5}} )
12
40The work function of a substance is
4.0eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately
A . ( 5400 A^{circ} )
в. ( 4000 A^{circ} )
c. ( 3100 A^{circ} )
D. 2200A ( ^{text {0 }} )
12
4139. Silver has a work function of 4.7 eV. When ultraviolet lich
of wavelength 100 mm is incident upon it, a potential
7.7 V is required to stop the photoelectrons from reaching
the collector plate. How much potential will be required
to stop the photoelectrons when light of wavelength 2001
mm is incident upon silver?
(a) 1.5 V
(b) 3.85 V
(c) 2.35 V
(d) 15.4 V
12
42Relation between wavelength of photon and electron of same energy is
( mathbf{A} cdot lambda_{p h}>lambda_{e} )
( mathbf{B} cdot lambda_{p h}<lambda_{e} )
( mathbf{c} cdot lambda_{p h}=lambda_{e} )
D. ( frac{lambda_{c}}{lambda_{p h}}= ) constant
12
4347. In Q. 46, the work function is
(a) 0.212 eV
(b) 0.313 eV
(c) 0.414 eV
(d) 0.515 eV
40
TL
12
44Light of wavelength ( lambda ), strikes a photoelectric surface and electrons are ejected with an energy E. If E is to be increased to exactly twice its original
value, the wavelength changes to ( lambda^{prime} )
where
A ( cdot x^{prime} ) is less than ( frac{lambda}{2} )
B. ( lambda^{prime} ) is greater than ( frac{lambda}{2} )
c. ( lambda^{prime} ) is greater than ( frac{lambda}{2} ) but less than ( lambda )
( lambda^{prime} lambda^{prime} ) is exactly equal to ( frac{lambda}{2} )
12
45A graph is plotted between uncertainty
in position and inverse of uncertainty in
wavelength for an electron. We get a
straight line passing through the origin.
Calculate voltage through which
electron is accelerated with
A. ( 150 mathrm{v} )
B. 75 V
c. 37.5
D. 300
12
468. If the kinetic energy of a free electron doubles, its
de Broglie wavelength changes by the factor
(a)
(b) 5
(c) 2
(AIEEE 2005)
12
47Calculate the velocity of an electron
having wavelength of ( 0.15 n m . ) Mass of an electron is: ( 9.109 times 10^{-28} g )
( left(h=6.626 times 10^{-27} e r g-sright) )
A ( cdot 2.062 times 10^{-8} mathrm{cms}^{-1} )
B. ( 2.062 times 10^{15} mathrm{cms}^{-1} )
c. ( 2.062 times 10^{10} mathrm{cms}^{-1} )
D. ( 4.84 times 10^{8} mathrm{cms}^{-1} )
12
48A water drop of radius ( 10^{-6} mathrm{m} ) is charged with one electron. The electric
field required to keep it stationary is (given density of water ( boldsymbol{rho}= )
( mathbf{1 0 0 0 k g} / boldsymbol{m}^{3} ; boldsymbol{g}=mathbf{9 . 8 m} / boldsymbol{s}^{2} )
A ( .2 .566 times 10^{5} V / m )
B . ( 1.283 times 10^{5} mathrm{V} / mathrm{m} )
c. ( 3.849 times 10^{5} mathrm{V} / mathrm{m} )
D. ( 5.132 times 10^{5} mathrm{V} / mathrm{m} )
12
49With the decrease in the wave length of the incident radiation the velocity of the photoelectrons emitted from a given metal
A. Remains same
B. Increases
c. Decreases
D. Increases first and then decreases
12
50Define the following:
Threshold frequency and work function.
12
51Light rays of wavelengths ( 6000 A ) and of
photon intensity 39.6 watts ( / m^{2} ) incidents on a metal surface. If only ( 1 % ) of photons incident on the surface emit photoelectrons, then the number of electrons emitted per second per
unit area from the surface will be
approximately:
[Planck constant ( boldsymbol{h}=mathbf{6 . 6 4} times mathbf{1 0}^{-mathbf{3 4} mathbf{J}} boldsymbol{s} )
Velocity of light ( left.=mathbf{3} times mathbf{1 0}^{mathbf{8}} boldsymbol{m} boldsymbol{s}^{-mathbf{1}}right] )
A ( cdot 12 times 10^{18} )
В. ( 10 times 10^{18} )
C ( .12 times 10^{17} )
D. ( 12 times 10^{15} )
12
52A homogeneous ball (mass ( =boldsymbol{m} ) ) of
ideal black material at rest is
illuminated with a radiation having a set of photons (wavelength ( =lambda ) ), each
with the same momentum and the
same energy. The rate at which photons fall on the ball is n. The linear
acceleration of the ball is:
( A cdot m lambda / n h )
B. ( n h / m lambda )
c. ( n h /(2 pi)(m lambda) )
D. ( 2 p m lambda / n h )
12
5353. Light of wavelength 0.6 um from a sodium lamp falls on
a photocell and causes the emission of photoelectrons
for which the stopping potential is 0.5 V. With light of
wavelength 0.4 um from a mercury vapor lamp, the
stopping potential is 1.5 V. Then, the work function (in
electron volts] of the photocell surface is
(a) 0.75 eV
(b) 1.5 eV
(c) 3 eV
(d) 2.5 eV
12
54The de-Broglie wavelength of a proton ( left(text {mass}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{2 7}} mathbf{k g}right) ) accelerated
through a potential difference of ( 1 mathrm{kV} ) is :
B . ( 0.9 times 10^{-12} mathrm{m} )
( c .7 dot{h} )
D. ( 0.9 times 10^{-19} n m )
12
55If the de-Broglie wavelength of a particle of mass ( m ) is 100 times its velocity then
its value in terms of its mass ( (m) ) and Planck’s constant ( (boldsymbol{h}) ) is:
A ( cdot frac{1}{10} sqrt{frac{m}{h}} )
в. ( 10 sqrt{frac{h}{m}} )
( c cdot frac{1}{10} sqrt{frac{h}{m}} )
D. ( 10 sqrt{frac{m}{h}} )
12
56Work function is
A. energy necessary to eject the electron from its orbit
B. energy necessary to eject an electron from within a metal body
C. minimum necessary energy to eject an electron from a metal surface
D. wavelength necessary for releasing an electron from a body
12
5773. As energy associated with changes with its wavelength,
often the reciprocal of the wavelength 1/2. is used to
describe energy associated with that wavelength. Then,
mark the correct equivalence.
(a) 1 eV = 5092.6 cm- and 1 cm-‘ = 1.2398 x 10-4 eV
(b) 1 eV = 1239.8 cm- and 1 cm-‘ = 8068 x 10-7eV
(c) 1 eV = 8068.8 cm-‘ and 1 cm-‘ = 6.65 x 10-19 eV
(d) 1eV=8065 x 10 cm and 1 cm’=1.2398 x 10 *eV
12
5861. A monochromatic source of light is placed at a large
distance d from a metal surface. Photoelectrons are ejected
at rate n, the kinetic energy being E. If the source is
brought nearer to distance d/2, the rate and kinetic energy
per photoelectron become nearly
(a) 2n and 2E
(b) 4n and 4E
(c) 4n and E
(d) n and 4E
12
59When a photon of energy ( 7 e V ) is made incident on a metal then the emitted
electron is stopped by a stopping potential of ( -5.5 V . ) The work function
of metal will be :
A. ( -1.5 e V )
B. ( 1.5 e V )
c. ( 12.5 e V )
D. ( 37.5 e V )
12
60If ( 10,000 V ) are applied across an ( X ) -ray tube, find the ratio of wavelength of the incident electrons and the shortest
wavelength of ( X ) -ray coming out of the X-ray tube, given ( e / m ) of electron ( = ) ( 1.8 times 10^{11} C k g^{-1} )
( mathbf{A} cdot 1: 10 )
B. 10: 1
c. 5: 1
D. 1: 5
12
6110
18. If a source of power 4 kW produces 1020 photons per
second, the radiation belongs to a part of the spectrum
called
(a) X-rays
(b) ultraviolet rays
(c) microwaves
(8) Witays aves
) yltraviolet raya IEEE 2010
12
6263. All electrons ejected from a surface by incident light of
wavelength 200 nm can be stopped before traveling 1 m
in the direction of a uniform electric field of 4 NC-. The
work function of the surface is
(a) 4 eV
(b) 6.2 eV
(c) 2 eV
(d) 2.2 eV
12
63A free particle with initial kinetic energy ( mathrm{E} ) and de-broglie wavelength ( lambda ) enters a region in which it has potential energy U. What is the particle’s new de-
Broglie wavelength?
A ( cdot lambda(1-U / E)^{-1 / 2} )
в. ( lambda(1-U / E) )
c. ( lambda(1-U / E)^{-1} )
D. ( lambda(1-U / E)^{1 / 2} )
12
64A surface has work function ( 3.3 e V )
Which of the following will cause
emission?
A. ( 100 W ) incandascent lamp
B. 40 ( W ) flouroscent lamp
c. ( 20 W ) sodium lamp
D. 20 ( W ) Hg lamp
12
6516. Radiation pressure on any surface
(a) is dependent on wavelength of the light used
(b) is dependent on nature of surface and intensity of light
used
(c) is dependent on frequency and nature of surface
(d) depends on the nature of source from which light is
coming and on nature of surface on which it is falling
12
66An ( alpha ) -particle and a proton are
accelerated from rest by a potential difference of ( 100 V . ) After this, their de
Broglie wavelengths are ( lambda_{alpha} ) and ( lambda_{p} )
respectively. The ratio ( lambda_{p} / lambda_{alpha}, ) to the nearest integer, is:
12
67The photons from Blamer series in
hydrogen spectrum having wavelength between ( 450 mathrm{nm} ) to ( 700 mathrm{nm} ) are incident
on a metal surface of work function 2
eV. Find the maximum kinetic energy of
one photo electron.
12
68An ( alpha- ) particle and a proton have their
masses in the ratio 4: 1 and charges
in the ratio ( 2: 1 . ) Find ratio of their de-
Broglie wavelengths when both move with equal velocities.
( mathbf{A} cdot 1: 4 )
B. 4: 1
c. 1: 2
( D cdot 2: 1 )
12
6911. The time by a photoelectron to come out after the photon
strikes is approximately
(a) 10-‘s
(b) 1045
(c) 10-10 s
(d) 10-16S (AIEEE 2006)
12
70In Millikan’s oil drop experiment, an oil drop of density 8 times of air is held
stationary by applying a field E. The field required to hold another drop of same radius and carrying same charge but density is 22 times the density of air is
( A cdot E )
B . 2E
c. зЕ
D. 4E
12
71In hydrogen spectrum, the wavelength of the line is ( 656 mathrm{nm} ), where as in the
spectrum of a distant galaxy, the line wavelength is ( 706 mathrm{nm} ). Estimated speed of galaxy with respect to the earth is :
A ( cdot 2 times 10^{8} m / s )
В. ( 2 times 10^{7} m / s )
c. ( 2 times 10^{6} mathrm{m} / mathrm{s} )
D. ( 2 times 10^{5} mathrm{m} / mathrm{s} )
12
72If ( 5 % ) of the energy supplied to a bulb is radiated as visible light, the number of visible quanta emitted per second by a
100W bullb, assuming the wavelength
of visible light to be ( 5.6 times 10^{-5} mathrm{cm}, ) is
A. ( 1.4 times 10^{19} )
B . ( 1.4 times 10^{20} )
( mathrm{c} cdot 2 times 10^{19} )
D. ( 2 times 10^{20} )
12
73The energy that should be added to an electron to reduce its de-Broglie wavelength from 1 nm to 0.5 nm is.
A. Four times the initial energy
B. Equal to the initial energy
c. Twice the initial energy
D. Thrice the initial energy
12
74An electronic transition from ( M ) shell
( =3 ) to ( K ) shell ( (n=1) ) takes place in a hydrogenatom. Find the wavelength of radiation emited. ( left(R=109,677 mathrm{cm}^{-1}right) )
A ( cdot 1026 A^{circ} )
( ^{circ} )
B . ( 1.026 times 10^{-5} mathrm{m} )
c. ( 1.026 times 10^{-3} mathrm{cm} )
D. none of these
12
75Two electrons are moving with nonrelativistic speeds perpendicular to each other. If corresponding de Broglie
wavelengths are ( lambda_{1} ) and ( lambda_{2}, ) their de
Broglie wavelength in the frame of
reference attached to their centre of
mass is:
( mathbf{A} cdot lambda_{C M}=lambda_{1}=lambda_{2} )
( ^{mathrm{B}} cdot frac{1}{lambda_{C M}}=frac{1}{lambda_{1}}+frac{1}{lambda_{2}} )
( ^{mathbf{C}} lambda_{C M}=frac{2 lambda_{1} lambda_{2}}{sqrt{lambda_{1}^{2}+lambda_{2}^{2}}} )
( lambda_{C M}=left(frac{lambda_{1}+lambda_{2}}{2}right) )
12
76Radiations of two photon’s energy, twice and ten times the work function of
metal are incident on the metal surface
successively. The ratio of maximum velocities of photoelectrons emitted in two cases is:
A . 1: 2
B. 1:3
( c cdot 1: 4 )
D. 1:
12
77Assume that a molecule is moving with the root mean square speed at temperature ( 300 mathrm{K} ). The de Broglie wavelength of nitrogen molecule is (Atomic mass of nitrogen ( =14.0076 mathrm{u}, mathrm{h} ) ( =mathbf{6 . 6 3} times mathbf{1 0}^{-mathbf{2 7}} boldsymbol{J} boldsymbol{s}, boldsymbol{k}_{boldsymbol{B}}=mathbf{1 . 3 8} times )
( mathbf{1 0}^{-mathbf{2 3}} boldsymbol{J} boldsymbol{K}^{-mathbf{1}}, mathbf{1} boldsymbol{u}=mathbf{1 . 6 6} cdot times mathbf{1 0}^{-mathbf{2 7}} boldsymbol{k} boldsymbol{g} )
( mathbf{A} cdot 2.75 times 10^{-11} m )
В. ( 2.75 times 10^{-12} m )
c. ( 3.24 times 10^{-11} mathrm{m} )
D. ( 3.24 times 10^{-12} mathrm{m} )
12
78Which metal(s) can be used to produce electrons by the photoelectric effect from given source of light?
A. Barium only
B. Barium or lithium
c. Lithium, tantalum or tungsten
D. Tungsten or tantalum
12
79The electric field of certain radiation is
given by the equation ( boldsymbol{E}= )
( 200left[sin left(4 pi times 10^{10}right) t+sin (4 pi xright. )
( left.left.mathbf{1 0}^{mathbf{1 5}}right) boldsymbol{t}right] ) falls in a metal surface having
work function ( 2.0 e V . ) The maximum
kinetic energy ( in eV) of the photoelectrons is [use Planck’s
constant ( (h)=6.63 times 10^{-34} J-s ) and
electron charge ( left(boldsymbol{E}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} boldsymbol{C}right) )
A. 3.3
B. 4.3
c. 5.3
D. 6.3
E. 7.3
12
80A charged oil drop is suspended in
uniform field of ( 3 times 10^{4} V / m ) so that it
neither falls nor rises. The charge on the drop will be: (take the mass of the
charge ( =mathbf{9 . 9} times mathbf{1 0}^{-15} mathbf{k g} ) and ( mathbf{g}= )
( left.10 m / s^{2}right) )
A . ( 3.3 times 10^{-18} mathrm{C} )
в. ( 3.2 times 10^{-18} mathrm{C} )
c. ( 1.6 times 10^{-18} mathrm{C} )
D. ( 4.8 times 10^{-18} mathrm{C} )
12
81The de Broglie wavelength of electron accelerated through ( V ) volt is nearly given by:
( underset{(i n A)}{lambda}=left[frac{x}{V}right]^{1 / 2} . ) Find the value of ( frac{x}{75} )
12
827. A material particle with a rest mass m, is moving with a
velocity of light c. Then, the wavelength of the de Broglie
wave associated with it is
(a) (hlm.c)
(b) zero
(c)
(d) (m.clh)
12
83To increase de-Broglie wavelength of an electron from ( 0.5 times 10^{-10} mathrm{m} ) to ( 10^{-10} mathrm{m} )
its energy should be
A. Increased to 4 times
B. Halvedd
c. Doubled
D. Decreases to fourth parttt
12
84Radiation, with wavelength ( 6561 A ) falls on a metal surface to produce photoelectrons. The electrons are made to enter a uniform magnetic field of ( 3 times )
( 10^{-4} mathrm{T} . ) If the radius of the largest
circular path followed by the electrons
is ( 10 mathrm{mm} ), the work function of the metal is close to?
A ( .0 .8 mathrm{eV} )
B. ( 1.1 mathrm{eV} )
c. 1.6 ev
D. 1.8 ev
12
85Identify the reason why an observer cannot detect the wave nature of a fast moving truck.
A. The momentum of the truck is too large
B. The velocity of the wave is too large
c. There are no waves to be detected
D. The frequency is too low
E. The wavelengths are too small
12
86de Broglie relation is true for
A. All particles
B. Charged particles only
c. Negatively charged particles only
D. Massless particles like photons only
12
87A body of mass ( 100 g ) moves at the speed of ( 36 k m / h ). The de-Broglie wavelength related to it is of the order
( boldsymbol{m} )
( left(h=6.626 times 10^{-34} J sright) )
A ( cdot 10^{-24} )
B . ( 10^{-14} )
c. ( 10^{-34} )
the ( 4^{-34} 4 )
D. ( 10^{-44} )
12
88( frac{L}{L} )12
89The electron microscope is based on the principle of
A. photoelectric effect
B. particle nature of electrons
c. particle nature of electron
D. dual nature of matter
12
90What determines the intensity of light in the photon picture of light?12
9129. The frequency of incident light falling on a photose
metal plate is doubled, the KE of the emitted photoelectrons
is
(a) double the earlier value
(b) unchanged
(c) more than doubled
(d) less than doubled
12
92Illuminating the surface of a certain metal alternately with light of
wavelength ( lambda_{2}=0.54 mu m ) and ( lambda_{2}= )
( 0.54 mu m, ) it was found that the
corresponding maximum velocities of photo electrons have a ratio ( eta=2, ) Find the work function of that metal.
A ( .6 .99 e V )
B. ( 1.9 e V )
c. ( 7.53 e V )
D. ( 1.88 e V )
12
93A monochromatic source of light
operating at ( 200 mathrm{W} ) emits ( 4 times 10^{20} )
photons per second. Find the wavelength of light.
A . 400 nm
B. 200nm
C ( .4 times 10^{-10} dot{A} )
D. None of these
12
94An oil drop of 10 excess electrons is
held stationary under a constant electric field of ( 3.65 times 10^{4} N C^{-1} ) in
Millikan’s oil drop experiment. The density of oil is ( 1.26 g c m^{-3} . ) Radius of
the oil drop is
(Take ( left.g=9.8 m s^{-2}, e=1.6 times 10^{-19} Cright) )
A ( cdot 1.04 times 10^{-6} mathrm{m} )
в. ( 4.8 times 10^{-5} mathrm{m} )
( mathbf{c} cdot 4.8 times 10^{-18} m )
D. ( 1.13 times 10^{-18} mathrm{m} )
12
9555. Monochromatic light incident on a metal surface emits
electrons with kinetic energies from zero to 2.6 eV. What
is the least energy of the incident photon if the tightly
bound electron needs 4.2 eV to remove?
(a) 1.6 eV
(b) From 1.6 eV to 6.8 eV
(c) 6.8 eV
(d) More than 6.8 eV
12
9634. In Q. 32, if the intensity of light is made 410, then the
saturation current will become
(a) 0.40 x 1 ua
(b) 0.40 x 2 ua
(c) 0.40 x 4 uA
(d) 0.40 x 8 UA
12
97The surface of a metal is illuminated
with the light of 400 nm. The kinetic energy of the ejected photoelectrons
was found to be ( 1.68 mathrm{eV} ). The work
function of the metal is :
( (h c=1240 mathrm{eV} . n m) )
A . ( 3.09 mathrm{eV} )
в. ( 1.41 mathrm{eV} )
c. ( 1.51 mathrm{eV} )
D. ( 1.68 mathrm{eV} )
12
98An oil drop of radius r carrying a charge q’ remains stationary in the presence of electric field of intensity E. If the density of oil is ( rho, ) then
( ^{mathbf{A}} cdot E=frac{4}{3} pi r^{3} rho g q )
B. ( quad E=frac{4}{3} pi r^{3} rho g )
c. ( _{E}=frac{4}{3} pi r^{3} rho g / q )
D. ( E=frac{4}{3} pi r^{3} rho / g^{3} )
12
99Davisson and Germer experiment
represents nature of the
electron.
A. Wave
B. Particle
c. wave and particle
D. Doesn’t represent any nature
12
100The work function of cesium metal is
2eV. It means that
A. The energy necessary to emit electrons from metal surface is ( 2 mathrm{eV} )
B. The energy of electrons emitted from metallic surface is ( 2 e v )
C. The value of photoelectric current is ( 2 mathrm{eV} )
D. The value of threshold frequency is ( 2 e v )
12
101The minimum amount of energy
required to emit an electron from a
metal surface is called
A. Force function
B. Power function
c. work function
D. None of the above
12
102An isolated metal body is illuminated with monochromatic light and is
observed to becomes charged to a steady positive potential ( 1.0 mathrm{V} ) with respects to the surrounding. the work function of the metal is ( 3.0 mathrm{eV} ). The
frequency of the incident light is
12
103The surface of some material is
radiated in turn by waves of ( lambda=3.5 times ) ( 10^{-7} ) and ( lambda=5.4 times 10^{-7} m ) respectively
The ratio of the stopping potential in the two cases in ( 2: 1 . ) The work function of
the metal is:
A . ( 1.05 e V )
B. ( 1.5 e V )
c. ( 2.05 e V )
D. ( 2.5 e V )
12
104Find the frequency of light which ejects electrons from a metal surface, fully
stopped by a retarding potential of ( 3.3 V ) If photo electric emission begins in
this metal at a frequency of ( 8 times 10^{14} mathrm{Hz} )
calculate the work function (in eV) for this metal.
12
105Work function is the energy required
A. To excite an atom
B. To produce X-rays
C. To eject an electron just out of the surface
D. To explode the atom
12
106A proton is accelerated to ( 225 V ). Its deBroglie wavelength is:
( mathbf{A} cdot 0.0019 n m )
B. ( 0.02 n m )
c. ( 0.003 n m )
D. ( 0.4 n m )
12
10712. Find the ratio of de Broglie wavelength of a proton and
an d-particle which have been accelerated through sam
potential difference.
(a) 2V2:1
(b) 3:2
(c) 3√2:1
(d) 2:1
12
108In Millikan’s experiment, the slope of ( v )
versus ( V_{o} ) graph was found to be
( 4.125 times 10^{-15} V s . ) Given ( e=1.6 times )
( 10^{-19} C, ) the value of Planck’s constant
is
B. ( 6.4 times 10^{-34} J s )
C ( .4 .125 times 10^{-34} mathrm{Js} )
D. ( 6.6 times 10^{-34} J s )
12
109The direction of the electric field in
Millikan’s oil drop experiments acts.
A. Downwards
B. Upwards
c. First upwards then downwards
D. First downwards, then upwards
12
11013. Electrons accelerated by potential V are diffracted from
a crystal. If d = 1 Å and i = 30°, V should be about
(h=6.6 x 10-34 Js, me = 9.1 x 10-kg, e = 1.6 x 10-19 C)
(a) 500 V
(b) 1000 V
(c) 2000 V
(d) 50 V
1.cc
12
11170. A silver ball of radius 4.8 cm is suspended by a thread in
the vacuum chamber. UV light of wavelength 200 nm is
incident on the ball for some times during which a total
energy of 1 x 10-‘J falls on the surface. Assuming on an
average one out of 10 photons incident is able to eject
electron. The potential on sphere will be
(a) 1V
(c) 3V
(d) Zero
(b) 2 V
12
112Find the frequency of 1 MeV photon. Given wavelength of a ( 1 mathrm{keV} ) photon is ( 1.24 times 10^{-9} m )
Hint: ( boldsymbol{E}=boldsymbol{h} boldsymbol{nu} )
12
113The photo electric work function for a metal surface is 4.125 eV. The cut-off
wavelength for this surface
A ( cdot 4125 ~ A^{circ} )
B. 2062.5 ( A^{circ} )
c. ( 3000 A^{circ} )
D. 6000A ( ^{text {о }} )
12
114A ( 200 g ) cricket ball is thrown with a
speed of ( 3.0 times 10^{3} mathrm{cm} ) sec ( ^{-1} ). What will
be its de Broglie’s wavelength? ( left(h=6.6 times 10^{-27} g c m^{2} s e c^{-1}right) )
( mathbf{A} cdot 1.1 times 10^{-32} c m )
B . ( 2.2 times 10^{-32} mathrm{cm} )
C ( .0 .55 times 10^{-32} mathrm{cm} )
D. ( 11.0 times 10^{-32} mathrm{cm} )
12
115The de-Broglie wavelength associated with a proton changes by ( 0.25 % ) if its
momentum is changed by ( P_{o} ). The initial momentum of proton is
A ( cdot 100 P_{o} )
в. ( 400 P_{o} )
( c cdot P_{o} / 400 )
D. ( P_{o} )
12
116Find energy of photon of wavelength ( mathbf{4 0 0 0} stackrel{boldsymbol{o}}{boldsymbol{A}} )12
117In the following diagram if ( V_{2}>V_{1} ) then
( mathbf{A} cdot lambda_{1}=sqrt{lambda_{2}} )
B ( cdot lambda_{1}lambda_{2} )
12
118Momentum of a photon of wavelength ( lambda )
is:
( A cdot h / lambda )
B. Zero
c. ( h lambda / c^{2} )
D. ( h lambda / c )
12
119The photoelectric threshold of a certain metal is 3000 A. If the radiation of ( 2000 A ) is incident on the metal
A. electrons will be emitted
B. positrons will be emitted
c. protons will be emitted
D. electrons will not be emitted
12
120The wavelength of a certain electron
transition in the hydrogen spectrum is 4864 A. Identify the transition.
A. Third line Balmer
B. First line Lyman
c. First line Paschen
D. second line Balmer
12
121A particle of mass ( mathrm{M} ) at rest decays into
particles of masses ( m_{1} ) and ( m_{2} ) having non -zero velocities. The ratio of the de
broglie wavelengths of the particles
( lambda_{1} / lambda_{2} ) is :
( mathbf{A} cdot m_{1} / m_{2} )
в. ( m_{2} / m_{1} )
( c )
D. m1.m2
12
122A microscope using suitable photons is employed to locate an electron in an atom within a distance of 0.1 A. The uncertainty of its velocity is
A. ( 5.79 times 10^{5} mathrm{ms}^{-1} )
B. ( 8.79 times 10^{5} mathrm{ms}^{-1} )
C. ( 5.79 times 10^{4} mathrm{ms}^{-1} )
D. ( 3.79 times 10^{5} mathrm{ms}^{-1} )
12
123The de Broglie wavelength ( (lambda) ) associated with a photoelectron varies
with the frequency ( ( v ) ) of the incident
radiation as, ( left[v_{0} text { is thrshold frequency }right] )
A ( cdot lambda propto frac{1}{left(v-v_{0}right)^{frac{3}{2}}} )
B. ( lambda propto frac{1}{left(v-v_{0}right)^{frac{1}{2}}} )
c. ( a lambda propto frac{1}{left(v-v_{0}right)^{frac{1}{4}}} )
D. ( lambda propto frac{1}{left(v-v_{0}right)} )
12
Davisson and Germer demonstrated
this by diffracting electrons
from crystals. The law governing the
diffraction from a crystal is obtained by requiring that electron waves reflected
from the planes of atoms in a crystal
interfere constructively (see figure). Electrons accelerated by potential Vare
diffracted from a crystal. If ( boldsymbol{d}=mathbf{1} boldsymbol{A}^{boldsymbol{o}} ) and
( i=30^{circ}, V ) should be about :
( left(h=6.6 times 10^{-34} j s, m=9.1 timesright. )
( mathbf{1 0}^{-mathbf{3 1}} mathbf{k g}, e=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} mathbf{c} )
A . 2000 v
B. ( 50 v )
c. 500 v
D. ( 1000 mathrm{v} )
12
125Light of two different frequencies whose photos have energies leV and 2.5eV respectively illuminate a metallic surface whose work function is ( 0.5 e v )
successively. Ratio of maximum speeds of emissions will be
( A cdot 1: 4 )
B. 1:
( c cdot 1: )
D. 1:
12
126In Hertz’s experiment the
of the
electromagnetic waves is equal to the kinetic energy of the charges oscillating between two spheres.
A. Frequency
B. Energy
c. wavelength
D. Velocity
12
12710. The potential difference applied to an X-ray tube is v
The ratio of the de Broglie wavelength of electron to the
minimum wavelength of X-ray is directly proportional to
(a) V
(b) VV
(d) y7/2
(c) 1312
12
128The de Broglie wavelength of an electron
in a metal at ( 27^{circ} mathrm{C} ) is ( left(text {Given } boldsymbol{m}_{e}=right. )
( mathbf{9 . 1} times mathbf{1 0}^{-mathbf{3 1}} mathbf{k g}, boldsymbol{k}_{boldsymbol{B}}=mathbf{1 . 3 8} times )
( left.10^{-23} J K^{-1}right) )
A ( cdot 6.2 times 10^{-9} mathrm{m} )
В. ( 6.2 times 10^{-10} mathrm{m} )
( mathbf{c} cdot 6.2 times 10^{-8} m )
D. ( 6.2 times 10^{-7} m )
12
129A proton, a neutron, an electron and an
( alpha ) -particle have same energy. Then their de Broglie wavelengths compare as:
( mathbf{A} cdot lambda_{p}=lambda_{n}>lambda_{e}>lambda_{alpha} )
B . ( lambda_{alpha}<lambda_{p}=lambda_{n}<lambda_{e} )
( mathbf{c} cdot lambda_{e}lambda_{alpha} )
( mathbf{D} cdot lambda_{e}=lambda_{p}=lambda_{n}=lambda_{alpha} )
12
130The de Broglie wavelength of an electron
moving with a velocity of ( 1.5 times ) ( 10^{8} m s^{-1} ) is equal to that of a photon.
Find the ratio of the kinetic energy of
the photon to that of the electron.
12
131The energy of a neutron in eV whose de-
Broglie wavelength is ( 1 mathrm{A} )
A ( cdot 1.67 times 10^{-22} z V )
В. ( 8.13 times 10^{-2} mathrm{eV} )
c. ( 6.62 times 10^{-22} e V )
D. ( 3.23 times 10^{-2} mathrm{eV} )
12
132( frac{sqrt{2}}{frac{1}{n}} )12
133The de Broglie wavelength of an electron having 80 eV of energy is nearly ( left(1 e V=1.6 times 10^{-19} J, ) Mass of electron right.
( =9 times 10^{-31} k g )
Planck’s constant ( =mathbf{6 . 6} times mathbf{1 0}^{-mathbf{3 4}} mathbf{J s} )
(nearly)
A . ( 140 A^{circ} )
B. 0.14 ( A^{0} )
( mathbf{c} cdot 14 A^{0} )
D. 1.4 ( A^{0} )
12
134The electron with The electron with de
Broglie wavelength ( lambda ) is bombarded on a metal target. Found that photons are emitted through de Broglie wavelength.
12
135A radiation is incident on a metal
surface of work function ( 2.3 e V ). The
600 nm. If the total energy of incident
radiation is ( 23 J ), then the number of
photoelectrons is
A. zero
B ( cdot>10^{4} )
( mathbf{c} cdot=10^{4} )
D. None of these
12
136The de-Broglie wavelength of a proton accelerated by ( 400 mathrm{V} ) is
A ( .0 .005 AA )
B . 1.0528 ,
c. ( 0.0568 dot{A} )
D. ( 0.0143 dot{A} )
12
137The work function of a metal in ( 4 e V . ) For
the emission of photoelectrons of zero velocity from the metal surface, the wavelength of the incident radiation should be
( mathbf{A} cdot 1700 hat{A} )
в. 2700 А
( c cdot 3100 hat{A} )
D ( cdot 5900 ),
12
138A monochromatic source of light
operating at ( 200 mathrm{W} ) emits ( 4 times 10^{20} )
photons per second. Find the
wavelength of the light ( left(i n times 10^{-7} mright) )
12
139What is the de Broglie wavelength of the electron accelerated through a potential difference of 100 Volt?
A ( . ) १२.२७ ( AA )
в. 1.227 ,
c. 0.1227 ,
D. 0.001227 ( dot{A} )
12
140Identify the statement which best
define the uncertainty principle?
A. We cannot know for certain when any given radioactive particle will undergo decay
B. We cannot know both the momentum and the position of a particle at the same time
c. The laws of physics are the same in all intertial reference frames
D. Light exhibits both wave and particle properties
E. An unobserved particle can be in two places at the same time
12
141The ratio of energy of photon of ( lambda=2000 )
( A^{o} ) to that of ( lambda=4000 A^{o} ) is :
( A cdot 2 )
B. 1/4
( c cdot 4 )
D. ( 1 / 2 )
12
142A proton and ( alpha ) -particle are accelerated through the same potential difference. The ratio of their de-Broglie wavelength
will be
A .1:
B. 1: 2
( c cdot 2: )
D. ( 2 sqrt{2}: 1 )
12
143A charged oil drop falls with terminal
velocity ( v_{0} ) in the absence of electric
field. An electric field E keeps it stationary. The drop acquires additonal charge ( q ) and starts moving upwards with velocity ( v_{0} . ) The initial charge on
the drop was
( A cdot 4 q )
B. 2a
( c cdot q )
D. ( frac{q}{2} )
12
144Electrons with de Broglie wavelength ( lambda ) are bombarded on a metal target. It is found that photons are emitted from the metal target. The minimum wavelength of emitted photons is ( [mathrm{m}= ) mass of eletron]12
145State de Broglie hypothesis.12
146The wavelength associated with a
photon of energy 3.31 eV is nearly
A. ( 4000 A^{circ} )
B. 3750 ( A^{circ} )
C ( .5000 A^{circ} )
D. 400 A ( ^{text {о }} )
12
147The surface of the metal is illuminated
with the light of 400 nm. The kinetic energy of the ejected photoelectrons was found to be ( 1.68 mathrm{eV} ), the work function of metal is :
A . ( 1.51 mathrm{eV} )
B. 1.42 ev
c. 3.0 ev
D. 1.68 ev
12
148Photons of energy 7 e ( V ) are incident on two metals ( A ) and ( B ) with work functions
( 6 mathrm{eV} ) and ( 3 mathrm{eV} ) respectively. The minimum de Broglie wavelengths of the emitted photoelectrons with maximum
energies are ( lambda_{A} ) and ( lambda_{B}, ) respectively
where ( boldsymbol{lambda}_{boldsymbol{A}} / boldsymbol{lambda}_{boldsymbol{B}} ) is nearly:
A. 0.5
B. 1.4
( c cdot 4.0 )
D. 2.0
12
149The de-Broglie wavelength of electron in second Bohr’s orbit is equal to
A. circumference of the orbit
B. half the circumference of the orbitt
c. twice the circumference of the orbit
D. four times circumference of the orbit
12
150Assertion
Mass of moving photon varies inversely as the wavelength.
Reason
Energy of the particle ( = ) Mass ( times ) (speed
of light) ( ^{2} )
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. If Assertion is incorrect but Reason is correct
12
15130. Lights of two different frequencies whose photons have
energies 1 and 2.5 eV, respectively, successively illuminate
a metal whose work function is 0.5 eV. The ratio of the
maximum speeds of the emitted electrons will be
(a) 1:5
(b) 1:4
(c) 1:2
(d) 1:1
launted through potential difference
At
12
152ILLUSTRATION 28.9 Will photoelectrons be emitted from
copper surface, of work function 4.4 eV, when illuminated by
a visible light?
12
153The force on a hemisphere of radius 1
( mathrm{cm} ) if a parallel beam of monochromatic light of wavelength 500 nm. falls on it with an intensity of ( 0.5 mathrm{W} / mathrm{cm}^{2}, ) striking the curved surface in a direction which
is perpendicular to the flat face of the hemisphere is:
(Assume the collisions to be perfectly inelastic)
A. ( 5.2 times 10^{-13} N )
В. ( 5.2 times 10^{-12} N )
( mathrm{c} cdot 5.22 times 10^{-9} mathrm{N} )
D. 0 n
12
154A ( alpha ) – particle is accelerated through a potential difference of ( V ) volts from rest. The de-Broglie wavelength associated with it is (in angstrom):
A ( cdot sqrt{frac{150}{V}} )
в. ( frac{0.286}{sqrt{V}} )
c. ( frac{0.101}{sqrt{V}} )
D. ( frac{0.983}{sqrt{V}} )
12
155If the mass of a microscopic particle a well as its speed are halved, the debroglie wavelength associated with the particle will
A. increased by a factor more than 2
B. increases by a factor of 2
c. decreases by a factor of 2
D. decrease by a factor more than 2
12
156A body of mass ( m ) is dropped freely from
a height ( h ). The de-Broglie wavelength of the body as it reaches the ground is:
A ( cdot frac{h}{sqrt{g H}} )
в. ( frac{h}{m sqrt{g H}} )
c. ( frac{h}{2 sqrt{g H}} )
D. ( frac{h}{m sqrt{2 g H}} )
12
157For intensity ( I ) of a light of wavelength ( mathbf{5 0 0 0} boldsymbol{A} ) the photoelectron saturation current is ( 0.40 mu A ) and stopping
potential is ( 1.36 V, ) the work function of metal is:
A . 2.47 ev
B. 1.36 ev
c. 1.10 ev
D. 0.43 ev
12
158The kinetic energy of most energetic electrons emitted from a metallic
surface is doubled when the wavelength of the incident radiation is changed
from 400 nm to 310 nm. The work
function of the metal is :
A ( .0 .9 e V )
B. 1.7 eV
c. 2.2 eV
D. 3.1 eV
12
15945. The kinetic energy of most energetic electrons emitted
from a metallic surface is doubled when the wavelength
a of the incident radiation is changed from 400 nm to
310 nm. The work function of the metal is
(a) 0.9 eV
(b) 1.7 eV
(c) 2.2 eV
(d) 3.1 eV
12
16060. A photon of wavelength 0.1 Å is emitted by a helium
atom as a consequence of the emission of photon. The
KE gained by helium atom is
(a) 0.05 eV
(b) 1.05 eV
(c) 2.05 eV
(d) 3.05 eV
12
161SICULUJ
50. In the experiment on photoelectric effect, the graph
between Ex(max) and v
is found to be a
straight line as shown
in figure.
The threshold freq-
uency and Planck’s 0
+
constant according to 27 2 3 4 6 8 10
this graph are
ux (10)1851
(a) 3.33 x 1018 -, 6x 10-34 J-s
(b) 6 x 10185-4, 6x 10-34 J-s
(c) 2.66 x 1018s!, 4 x 10-34 J-s
(d) 4 x 10185-1,3 x 10-34 J-s
EK (Max)* 10-15 joule
12
162The de-Broglie wavelength of an electron in the ground state of the hydrogen atom is :
A ( cdot pi r^{2} )
в. ( 2 pi r )
( c . pi r )
D. ( sqrt{pi r} )
12
163Threshold wavelength depends on
B. Work function of the substance
C. Velocity of electrons
D. Energy of electrons
12
164The wavelength of de broglie waves associated with a beam of protons of
kinetic energy ( 5 times 10^{2} mathrm{eV} )
(Mass of each photon ( =mathbf{1 . 6 7} times mathbf{1 0}^{-mathbf{2 7}} mathbf{K g} )
( boldsymbol{h}=mathbf{6 . 6 2} times mathbf{1 0}^{-mathbf{3 4}} mathbf{J s} )
A. ( 2.42 times 10^{-12} mathrm{m} )
B . ( 4.24 times 10^{-12} mathrm{m} )
c. ( 1.82 times 10^{-12} mathrm{m} )
D. ( 1.28 times 10^{-12} mathrm{m} )
12
165The de-Broglie wavelength of an electron travelling with ( 10 % ) of velocity of light is equal to:
A. ( 242.4 mathrm{pm} )
B. 24.2pm
c. ( 2.42 mathrm{pm} )
D. 0.2424 pm
12
166In Millinkan’s oil drop experiment, a charged oil drop of mass ( 3.2 times 10^{-14} k g )
is held stationary between parallel plates ( 6 m m ) apart, by applying a
potential difference of ( 1200 V ) between them. How many electrons does the oil
drop carry? ( left(text { Given } g=10 m s^{-2}right) )
A. 7
B. 8
( c cdot 9 )
D. 10
12
167What is the ratio of wavelength of radiations emitted, when an electron in
hydrogen atom jumps from fourth orbit to second orbit and from third orbit to
second orbit?
A . 27 : 25
B. 20:27
c. 20: 25
D. 25 : 27
12
168A quartz lamp with iodine vapour releases ultraviolet light which falls on
a photoelectric cell. If a thick glass plate is now introduced between the
lamp and photoelectric cell then:
A. the photoelectric current increases
B. the maximum kinetic energy of photoelectrons decreases
c. the photoelectric current decreases
D. the maximum kinetic energy of photoelectrons increases
12
169For the Bohr’s first orbit of
circumference ( 2 pi r, ) the de-Broglie wavelength of revolcing electron will be.
A ( .2 pi r )
B . ( pi r )
c. ( frac{1}{2 pi r} )
D. ( frac{1}{4 pi r} )
12
17033. In Q. 32, if the intensity of light is made 410, then the
stopping potential will become
(a) 1.36 x 1 V
(b) 1.36×2 V
(c) 1.36X3 V
(d) 1.36 X 4 V
@ 1.36X1V
(136×2 V
12
171ILLUSTRATION 28.4 A plate of mass 10 g is in equilibrium in
air due to the force exerted by a light beam on the plate.
Calculate power of the beam. Assume that the plate is perfectly
absorbing.
12
172Which metal will be suitable for a
photoelectric cell using light of wavelength ( 4000 A ) The work functions of sodium and copper are respectively 2eV and ( 4 e v )
A. Sodium
B. Copper
c. Both
D. None of these
12
173If the cathode is cesium ( (phi=1.9 e V) )
what will be the cut off voltage?
A. zero
B . 0.36 V
c. ( 0.46 mathrm{v} )
D. ( 0.56 mathrm{v} )
12
17420. This question has Statement 1 and Statement 2. Of the
four choices given after the statements, choose the one
that best describes the two statements
Statement 1: A metallic surface is irradiated by a
monochromatic light of frequency f> fo (the threshold
frequency). The maximum kinetic energy and the
stopping potential are Kmax and V, respectively. If the
frequency incident on the surface is doubled, both the
Kmax and Voare also doubled.
Statement 2: The maximum kinetic energy and the
stopping potential of photoelectrons emitted from a
surface are linearly dependent on the frequency of
incident light.
(a) Statement 1 is true but statement 2 is false.
(b) Statement 1 is true, statement 2 is true, statement 2 is
the correct explanation of statement 1.
(c) Statement 1 is true, statement 2 is true, statement 2 is
not the correct explanation of statement 1.
(d) Statement 1 is false but statement 2 is true.
(AIEEE 2011)
12
175(d) 41
58. A homogeneous ball (mass = m) of ideal black material at
rest is illuminated with a radiation having a set of photons
(wavelength = 2), each with the same momentum and the
same energy. The rate at which photons fall on the ball is n.
The linear acceleration of the ball is
(a) mNnh
(b) nh/m2
(c) nh/(27)(m2) (d) 2pmNinh sd be
104
21
12
176Show that it is not possible for a photon to be completely absorbed by a free
electron.
12
light of frequencies ( f_{1} ) and ( f_{2} ). If the
velocities of the photoelectrons (of
mass ( m ) ) coming out are ( v_{1} ) and ( v_{2} )
respectively, then
A.
[
v_{1}-v_{2}=left[frac{2 h}{m}left(f_{1}-f_{2}right)right]^{frac{1}{2}}
]
B. ( v_{1}^{2}-v_{2}^{2}=frac{2 h}{m}left(f_{1}-f_{2}right) )
c. ( quad v_{1}+v_{2}=left[frac{2 h}{m}left(f_{1}-f_{2}right)right]^{frac{1}{2}} )
D. ( v_{1}^{2}+v_{2}^{2}=frac{2 h}{m}left(f_{1}-f_{2}right) )
12
178A metal surface is illuminated by light
of two different wavelengths ( 248 n m )
and ( 310 n m . ) The maximum speeds of
the photoelectrons corresponding to
these wavelengths are ( u_{1} ) and ( u_{2} )
respectively. If the ratio ( u_{1}: u_{2}=2: 1 )
and ( h c=1240 e V n m, ) the work
function of the metal is nearly:
( mathbf{A} cdot 3.7 mathrm{eV} )
B. ( 3.2 e V )
c. ( 2.8 e V )
D. ( 2.5 e V )
12
179ILLUSTRATION 28.2 A bulb lamp emits light of mean
wavelength of 4500 Å. The lamp is rated at 150 W and 8% of
the energy appears as emitted light. How many photons are
emitted by the lamp per second?
12
180If there are two de-Broglie waves formed in an orbit of H-atom then the energy of
electron in that orbit is.
A. ( -3.4 e V )
B. ( -13.6 e V )
c. ( -9.06 e V )
D. ( 1.51 mathrm{eV} )
12
181What is the De-Broglie wavelength associated with the hydrogen electron in its third orbit :
A ( .9 .96 times 10^{-10} mathrm{cm} )
В. ( 9.96 times 10^{-8} mathrm{cm} )
( mathrm{c} cdot 9.96 times 10^{4} mathrm{cm} )
D. ( 9.96 times 10^{8} mathrm{cm} )
12
182If the kinetic energy of the moving
particle is ( boldsymbol{E} ), then the de Broglie wavelength is
A ( cdot lambda=frac{h}{sqrt{2 m E}} )
B. ( lambda=frac{sqrt{2 m E}}{h} )
c. ( lambda=h sqrt{2 m E} )
D. ( lambda=frac{h}{E sqrt{2 m}} )
12
18367. A sodium metal piece is illuminated with light of wavelength
0.3 um. The work function of sodium is 2.46 eV. For this
situation, mark out the correct statement(s).
(a) The maximum kinetic energy of the ejected
photoelectrons is 1.68 eV
(b) The cut-off wavelength for sodium is 505 nm
(c) The minimum photon energy of incident light for
photoelectric effect to take place is 2.46 eV
(d) All of the above
12
184The de-Broglie wavelength of a neutron
( operatorname{at} 927^{0} mathrm{C} ) is ( lambda . ) Its wavelength at ( 27^{0} mathrm{C} ) is:
( A cdot frac{lambda}{2} )
B. ( lambda )
( c cdot 2 lambda )
D. ( 4 lambda )
12
185Why we do not observe de Broglie wave in daily life?12
18611. The eye can detect 5 x 104 photons per square metre per
sec of green light (a = 5000 Å) while the ear can detect
10-\$(W/m?). The factor by which the eye is more sensitive
as a power detector than the ear is close to be
(a) 5
(b) 10
(d) 15 olib b on
(c) 106
12
187If an electron and a proton have the same de-Broglie wavelength, then the kinetic energy of the electron is :
A. zero
B. Less than that of a proton
c. More than that of a proton
D. Equal to that of a proton
12
188On increasing the applied potential difference in X-ray tube This question has multiple correct options
A. The intensity of emitted radiation increases.
B. The minimum wavelength of emitted radiation increases
c. The intensity of emitted radiation remains unchanged.
D. The minimum wavelength of emitted radiation decreases
12
189The work function of aluminium is 4.2
eV. If two photons, each of energy 3.5 eV strike an electrons of aluminium, then
emission of electrons
A. Will be possible
B. Will not be possible
c. Data is incomplete
D. Depends upon the density of the surface
12
190Photon having the energy equivalent to the binding energy of 4th state of ( boldsymbol{H} boldsymbol{e}^{+} ) atom is used to eject an electron from the metal surface of work function 1.4
eV. If electrons are further accelerated
through the potential difference of ( 4 mathrm{V} ) then determine the minimum value of
de-Broglie wavelength associated with the electron.
в. 2.5 А ( ^{text {о }} )
( c cdot 7.6 A^{circ} )
D. ( 10 A^{circ} )
12
191The frequency and the intensity of a
beam of light falling on the surface of a
photoelectric material are increased by
a factor of two. This will:
A. Increase the maximum kinetic energy of the photoelectrons by 2 and photoelectric current by a factor of ( 1 / 2 )
B. Increase the maximum kinetic energy of the photoelectrons, and increase the photoelectric current by a factor of 2
C. Increase the maximum kinetic energy of the photoelectrons by a factor of 2 and will have no effect on the magnitude of the photoelectric current produced
D. Not produced any effect on the kinetic energy of the emitted electrons but will increase the photoelectric current by a factor of 2
12
192Calculate the de Broglie wavelength of an electron having kinetic energy of
( 1.6 times 10^{-6} ) erg ( left(m_{e}=9.11 timesright. )
( mathbf{1 0}^{-mathbf{2 8}} boldsymbol{g}, boldsymbol{h}=mathbf{6 . 6 2} times mathbf{1 0}^{-mathbf{2 7}} mathbf{e r g}-boldsymbol{s e c} )
B . ( 0.00029 A^{circ} )
c. ( 0.0122 A^{circ} )
D. ( 1.29 A^{circ} )
12
193In H-atom, if ‘x’ is the radius of the first
Bohr orbit, de Broglie wavelength of an electron in 3rd orbit is :
( mathbf{A} cdot 3 pi x )
в. ( 6 pi x )
c. ( frac{9 x}{2} )
D. ( frac{x}{2} )
12
194A ruby laser produces radiations of wavelengths, ( 662.6 mathrm{nm} ) in pulse
duration are ( 10^{-6} ) s. If the laser produces
( 0.39 mathrm{J} ) of energy per pulse, how many photons are produced in each pulse?
A ( cdot 1.3 times 10^{9} )
B . ( 1.3 times 10^{18} )
c. ( 1.3 times 10^{27} )
D. ( 3.9 times 10^{18} )
12
195An ( alpha- ) particle and a proton have their
masses in the ratio 4: 1 and charges
in the ratio 2: 1

Find ratio of de-Broglie wavelengths
when both have equal momentum.
( mathbf{A} cdot 2: 1 )
B. 1: 1
( mathbf{c} cdot 4: 1 )
D. 1: 4
E .1: 4

12
196Gases begin to conduct electricity at
low pressure because:
A. at low pressure gases turn to plasma
B. colliding electrons can acquire higher kinetic energy due to increased mean free path leading to ionisation of atoms
C . atoms break up into electrons and protons
D. the electrons in atoms can move freely at low pressure
12
197Draw a neat, labelled energy level diagram for H atom showing the transitions. Explain the series of spectral lines for H atom, whose fixed
inner orbit numbers are 3 and 4
respectively. The work functions for potassium and caesium are ( 2.25 mathrm{eV} ) and
2.14eV respectively. Is the photoelectric effect possible for either of them if the
incident wavelength is ( 5180 A ? ) [Given: Planck’s constant= 6.63 ( x )
( 10^{-34} mathrm{J}_{. mathrm{S}} )
Velocity of light ( =3 times 10^{8} m / s ; 1 e V= )
( left.mathbf{1} . mathbf{6} times mathbf{1 0}^{-mathbf{1 9}} mathbf{J}right] )
12
198Find the frequency of 1 MeV photon. Given wavelength of a ( 1 mathrm{keV} ) photon is ( 1.24 times 10^{-9} m )
Hint: ( boldsymbol{E}=boldsymbol{h} boldsymbol{nu} )
12
199A material particle with a rest mass
( m_{0}^{prime} ) is moving with speed of light ‘c’ The de-Broglie wavelength associated is given by
( ^{A} cdot frac{h}{m_{0} c} )
в. ( frac{m_{0}}{h} )
c. zero
( D cdot infty )
12
20041. Light of wavelength a strikes a photoelectric surface
and electrons are ejected with kinetic energy K. If Kis
to be increased to exactly twice its original value, the
wavelength must be changed to l’ such that
(a) X’ 1/2
(c) 2> X’> N2 (d) X = N2
12
201For wave connected with proton, debroglie wavelength change by ( 0.25 % ) if
its momentum change by ( P_{0} ) initial
momentum =
A. ( 100 P_{0} )
в. ( frac{P_{0}}{400} )
c. ( 401 P_{0} )
D. ( frac{P_{0}}{100} )
12
202A proton and an electron are accelerated by same potential difference starting from rest have de-
Brogile wavelength ( lambda_{p} ) and ( lambda_{e^{*}} )
A ( cdot lambda_{e}=lambda_{p} )
B . ( lambda_{0}lambda_{p} )
D. none of these
12
20337. The work function of a metallic surface is 5.01 eV.
The photoelectrons are emitted when light of wavelength
2000 A falls on it. The potential difference applied to stop
the fastest photoelectrons is ſh = 4.14 x 10- eVs]
(a) 1.2 V
(b) 2.24 V
(c) 3.6 V
(d) 4.8 V
12
204Energy equivalent to ( 10.00 mathrm{cm}^{-1} ) is:
A ( .2 .0 times 10^{-22} ) J per atom
B . 28.6 ( times 10^{-3} ) kcal.mol ( ^{-1} ) photon
c. ( 12.0 times 10^{-2} k J . m o l^{-1} ) photon
D. All of the above
12
205In the Millikan’s oil drop experiment the oil drop is subjected to a horizontal electric field of ( 4 mathrm{N} / mathrm{C} ) and the drop moves with a constant velocity
making an angle ( 45^{0} ) to the horizontal. If
the weight of the drop is W. The charge on the drop is (neglect buoyancy)
A. w
B. W/4
c. w/2
D. 3W/4
12
the wave function?
A. ( psi ) may be zero
B. ( psi ) must be single value, continuous
C . ( psi ) has no physical significance
D. ( psi ) gives the probability density of finding electrons.
12
207Two particles ( A ) and ( B ) have de-Broglie’s wavelengths ( 30 A ) and ( 20 A, ) combined to form a particle C. Momentum is conserved in this process. The possible de-Broglie’s wavelength of C is :
(the motion is one dimensional)
A ( cdot 12 AA )
в. 20 ,
( c .10 hat{A} )
D. 22 a
12
208Find the energy of photon in each of the following:
A. Microwaves of wavelength ( 1.5 mathrm{cm} )
B. Red light of wavelength 660 nm
C. Radiowaves of frequency ( 96 M H z )
D. ( X- ) rays of wavelength 0.17 nm
12
209Choose the correct statement
A. Any charged particle in rest is accompanied by matter waves.
B. Any uncharged particle in rest is accompanied by matter waves.
C. The matter waves are waves of zero amplitude.
D. The matter waves are waves of probability amplitude.
12
210Calculate the maximum kinetic energy
(in eV) of the emitted photoelectrons.
A . 1.5
B. 2.36
c. 3.85
D. 4.27
12
211Assertion
An electron cannot exist in the nucleus.
Reason

The de Broglie wavelength of an electron is much smaller than the diameter of
the nucleus.

Read the above assertion and reason
and choose the correct option regarding
¡t.
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
212Show that de Broglie wavelength of electrons accelerated ( V ) volts is very
nearly given by:
( lambda(i n dot{A})=frac{150^{1 / 2}}{V} )
12
213represents the variation of particle momentum with associated de Broglie
wavelength?
( mathbf{A} )
B.
( c )
( D )
12
214The voltage required to balance an oil drop carrying 10 electrons between the plates of a capacitor which are ( 10 mathrm{mm} ) apart, is (Given mass of the oil drop= ( left.mathbf{3} cdot mathbf{2} times mathbf{1 0}^{-mathbf{1 5}} mathbf{k g}, boldsymbol{e}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{1 9}} mathbf{C}right) )
A . ( 16 v )
B. 160 V
c. ( 196 v )
D. ( 19.6 v )
12
215Radiation of two photon energies twice and five times the work function of
metal are incident successively on the metal surface. The ratio of the
maximum velocity of photoelectrons emitted is the two cases will be :
A .1: 2
B . 2: 1
c. 1: 4
D. 4: 1
12
216Write the formula for de Broglie wavelength. An electron is moving with speed of ( 0.5 times 10^{3} m / s . ) Find the de
Broglie wavelength associated with it.
12
217Light of frequency ( v ) is incident on a
metal of threshold frequency ( v_{0} . ) Then work function of metal will be:
A ( . h v )
в. ( h v_{0} )
( mathbf{c} cdot hleft(v-v_{0}right) )
D. ( hleft(v+v_{0}right) )
12
218The de Broglie wavelength of an electron
accelerated by an electric field of ( V ) volt is given by:
A ( cdot lambda=frac{1.23}{sqrt{m}} )
в. ( lambda=frac{1.23 m}{sqrt{h}} m )
c. ( lambda=frac{1.23}{sqrt{V}} n m )
D. ( lambda=frac{1.23}{V} )
12
219If the momentum of an electron is
changed by ( P, ) then the de-Broglie wavelength associated with it changes by ( 0.5 % ). The initial momentum of
electron will be :
( mathbf{A} cdot 400 P )
в. ( frac{P}{200} )
( c cdot 100 P )
D. 200P
12
220de-Broglie wavelength associated with
an electron revolving in the ( n^{t h} ) state of hydrogen atom is directly proportional
to
A ( . n )
в. ( frac{1}{n} )
c. ( n^{2} )
D. ( frac{1}{n^{2}} )
12
2213. Two identical photocathodes receive light of frequencies
fi and f2. If the velocities of the photoelectrons (of mass
m) coming out are, respectively, V, and V2, then
(a) v, – vz = [phy Cr, -1))”?
(b) vi – vi = m (81-f2)
(c) vi + vz = [ Pahle (5 +5]
(d) vi – v; = Pho (5, + f2)
(AIEEE 2003)
12
222Two particles ( A_{1} ) and ( A_{2} ) of masses
( boldsymbol{m}_{1}, boldsymbol{m}_{2}left(boldsymbol{m}_{1}>boldsymbol{m}_{2}right) ) have the same de
Broglie wavelength. Then
A. their momenta are the same
B. their energies are the same.
c. momentum of ( A_{1} ) is less than momentum of ( A_{2} )
D. energy of ( A_{1} ) is more than the energy of ( A_{2} )
12
223ILLUSTRATION 28.7 An electron microscope uses electrons
accelerated by a voltage of 50 kV. Determine the de Broglie
wavelength associated with the electrons. If other factors (such
as numerical aperture, etc.) are taken to be roughly the same,
how does the resolving power of an electron microscope
compare with that of an optical microscope which uses yellow
light?
12
224In a photo-electric cell, a retarding
potential of ( 0.5 V ) is required to block
the movement of electrons from the
cathode when monochromatic light of wavelength ( 400 n m ) is incident on its surface. Find the work function of the
material of the cathode.
12
225A proton and electron are accelerated by same potential difference starting from
the rest have de-Broglie wavelength ( lambda_{p} )
and ( lambda_{e} )
A ( cdot lambda_{e}=lambda_{p} )
в. ( lambda_{e}lambda_{p} )
D. none of these
12
226The potential energy of a particle of
mass ( m ) is given by ( V(x)= ) ( left{begin{array}{cc}boldsymbol{E}_{0} mathbf{0} & leq boldsymbol{x} leq mathbf{1} \ mathbf{0} & boldsymbol{x}>mathbf{1}end{array}right} )
( lambda_{1} ) and ( lambda_{2} ) are the de-Broglie
wavelengths of the particle, when ( 0 leq )
( x leq 1 ) and ( x>1 ) respectively.

If the total energy of particle is ( 2 E_{0} )
find ( left(lambda_{1} / lambda_{2}right) )

12
227A radiation is incident on a metal of
work function ( 2.3 e V . ) The incident
radiation is ( 600 n ) m.lf the total energy of
incident radiation is ( 23 J ), then the
number of photoelectrons is
A. zero
B ( .<10^{4} )
( mathbf{c} .=10^{4} )
D. ( infty )
12
228The ratio of the wavelengths of a photon and that of an electron of same energy ( boldsymbol{E} ) will be ( [boldsymbol{m} text { is mass of electron }] )
A ( cdot sqrt{frac{2 m}{E}} )
в. ( sqrt{frac{E}{2 m}} )
( c cdot c sqrt{frac{2 m}{E}} )
D. ( sqrt{frac{E c}{2 m}} )
12
229len
6. Ka wavelength emitted by an atom of atomic number
Z= 11 is 2. The atomic number for an atom that emits K,
(a) Z=6
(b) Z=4
(c) Z= 11
(d) Z=44
and
12
230If the ratio of de-Broglle wavelength of a proton and an ( alpha- ) particle is 1: 3
then
12
231A monochromatic source of light
operating at ( 200 mathrm{W} ) emits ( 4 times 10^{20} )
photons/second. Then the wavelength of light used is
A. 3000 ( A^{0} )
B . ( 5000 A^{0} )
c. ( 4000 A^{0} )
D. ( 6000 A^{circ} )
12
232Assertion
If the potential difference applied to an electron is made 4 times, the de Broglie
wavelength associated is halved.
Reason
On making potential difference 4 times, velocity is doubled and hence ( d ) is halved.
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. Both Assertion and Reason are incorrect
12
2338. The minimum intensity of light to be detected by human
eye is 10-W/m?. The number of photons of wavelength
56% 10′ m entering the eye, with pupil area 10 m, per
second for vision will be nearly
(a) 100
(b) 200
(e) 300
(d) 400
12
234One milliwatt of light of wavelength ( lambda=4560 A ) is incident on a cesium
metal surface. Calculate the electron
current liberated. Assume a quantum efficiency of ( boldsymbol{eta}=mathbf{0 . 5 %} ). [Work function
for cesium ( =1.89 e V] ) take ( h c= )
( 12400 e V-A )
12
235A particle of mass ( mathrm{m} ) is projected from
ground with velocity u making angle ( theta ) with the vertical. The de Broglie wavelength of the particle at the highest point is
( A cdot infty )
B. ( h / m u ) sin ( theta )
c. ( h / m u cos theta )
( mathbf{D} cdot h / m u )
12
236A particle moves in a closed orbit
around the origin, due to a force which
is directed towards the origin. The de Broglie wavelength of the particle varies
cyclically between two values ( lambda_{1} ) and ( lambda_{2} )
with ( lambda_{1}>lambda_{2} . ) Which of the following
statement is true?
A. The particle could be moving in an circular orbit with origin as centre
B. The particle could be moving in an parabolic orbit with origin as its focus
C. When the de Broglie wave length is ( lambda_{1} ), the particle is nearer the origin than when its value is ( lambda_{2} )
D. When the de Broglie wavelength is ( lambda_{2} ), the particle is nearer the origin than when its value is ( lambda_{1} )
12
237The de Broglie wavelength of a particle
of mass 1 gram and velocity 100 ms ( ^{-1} )
is:
A. ( 6.63 times 10^{-35} )
В. ( 6.63 times 10^{-34} )
c. ( 6.63 times 10^{-33} )
D. ( 6.63 times 10^{-32} )
12
238An electron in an excited state of ( L i^{2+} )
ion has angular momentum 3 h/2 ( pi ). The
de Broglie wavelength of the electron in
this state in ( p pi alpha_{0} ) (where ( alpha_{0} ) is the Bohr
radius). The value of ( p ) is :
12
239If ( lambda_{0} ) is the de Broglie wavelength for a proton accelerated through a potential difference of ( 100 mathrm{V}, ) the de Broglie
wavelength for ( alpha ) -particle accelerated through the same potential difference is
A ( cdot 2 sqrt{2} lambda_{0} )
B. ( frac{lambda_{0}}{2} )
( c cdot frac{lambda_{0}}{2 sqrt{2}} )
D. ( frac{lambda_{0}}{sqrt{2}} )
12
240The work function of tungsten coated with Barium Oxide is nearly
A. 5 ev
B. 10 ev
( c cdot 1 e v )
D. 0.01 ev
12
241If alpha particle, proton and electron
move with the same momentum, then
their respective de-Broglie wavelengths
( lambda_{alpha}, lambda_{p}, lambda_{e} ) are related as
A ( cdot lambda_{alpha}=lambda_{p}=lambda_{e} )
B . ( lambda_{alpha}<lambda_{p}lambda_{p}>lambda_{e} )
D. ( lambda_{p}>lambda_{e}>lambda_{alpha} )
E ( cdot lambda_{p}<lambda_{e}<lambda_{alpha} )
12
242Write object of Dacisson and Germer’s experiment. Draw a labelled diagram of its parctical arrangement.12
243Threshold wavelength for a metal
having work function ( omega_{0} ) is ( lambda . ) Then the
threshold wavelength for the metal
having work function ( 2 omega_{0} ) is
( A cdot 4 lambda )
B. 2lambda
( c cdot lambda / 2 )
D. ( lambda / 4 )
12
244The process of photoelectric emission depends on
A. Temperature of incident light
B. Nature of surface
c. speed of emitted photo electrons
D. Speed of the incident light
12
245In photoelectric effect, the slope of the straight line graph between stopping potential and frequency of the incident light gives the ratio of Planck’s constant
to
A. Charge of electron
B. Work function
c. Photoelectric current
D. K.E. of electron
12
246The relation between energy E and momentum p of a photon is
A ( . E=p c )
B. ( E=frac{p}{c} )
c. ( p=E c )
12
247The work function for the surface of
aluminium is ( 4.2 mathrm{eV} ). How much
potential difference will be required to stop the emission of maximum energy electrons emitted by light of ( 2000 dot{A} ) wavelength? What will be the wavelength of that incident light for
which stopping potential will be ( 0 ? )
12
248Assertion
When monochromatic light falls on a photosensitive material, the number of
photo electrons emitted per second is ( n )
and their maximum kinetic energy is
( K_{m a x} . ) If the intensity ( I ) of the incident
light is doubled, ( n ) is doubled but ( K_{m a x} )
remains the same.
Reason
The value of ( n ) is directly proportional to
( I ) but ( K_{max } ) is independent of ( I )
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. Both Assertion and Reason are incorrect
12
249What are de-Broglie waves? Establish the de-Broglie wavelength equation.12
250The electricity produced by creating photo electrons is called:
A. Photoelectricity
B. Static electricity
c. Thermal electricity
D. Piezoelectricity
12
251Define the photoelectric effect. Write the laws of the photoelectric effect.12
2521. Sodium and copper have work functions 2.3 eV and
4.5 eV, respectively. Then the ratio of the wavelengths
is nearest to
(a) 1:2
(b) 4:1
(c) 2:1
(d) 1:4 (AIEEE 2002)
|
12
253Find the minimum wavelength of ( X ) -ray produced if ( 10 mathrm{kV} ) potential difference is applied across the anode and cathode of the tube.
A ( cdot 12.4 mathrm{A}^{circ} )
B. 12.4 nm
( c cdot 1.24 mathrm{nm} )
D. ( 1.24 mathrm{A}^{circ} )
12
254The work function of a metal is ( 6 e V ). If
two photons each having energy ( 4 e V )
strike with the metal surface
(i) Will the emission be possible?
(ii) Why?
12
2555. The work function of a substance is 4.0 eV. The longest
wavelength of light that can cause photoelectron emission
from this substance is approximately
(a) 540 nm
(b) 400 nm
(c) 310 nm
(d) 220 nm (AIEEE 2004)
11:
13
11
12
256The work function of metal is in the
range of ( 2 e V ) to ( 5 e V ). Find which of the
following wavelength of light cannot be used for photoelectric effect:
(Consider, Plank constant ( =mathbf{4} times )
( 10^{-15} e V s, ) velocity of light ( =3 x )
( left.mathbf{1 0}^{mathbf{7}} boldsymbol{m} / boldsymbol{s}right) )
A. 510 nm
B. 650 nm
( c .400 mathrm{nm} )
D. 570 nm
12
257Define :
photoelectric work function.
12
258An electron and a proton have the same De Broglie wavelength. Then the kinetic energy of the electron is:
A. zero
B. Infinity
c. Equal kinetic energy of proton
D. Greater than the kinetic energy of proton
12
259The time taken by a photoelectron to come Out after the photon strikes is approximately.
( mathbf{A} cdot 10^{-1} s )
B. ( 10^{-2} s )
( mathbf{c} cdot 10^{-10} s )
D. ( 10^{-16} s )
12
26064. If the short wavelength limit of the continous spectrum
coming out of a Coolidge tube is 10 Å, then the de Broglie
wavelength of the electrons reaching the target metal in
the Coolidge tube is approximately
(a) 0.3 Å
(b) 3 Å
(c) 30 Å
(d) 10 Å
12
261The energy of a photons is equal to the
kinetic energy of a proton. If ( lambda_{1} ) is the de
Broglie wavelength of a proton, ( lambda_{2} ) the wavelength associated with the photon, and if the energy of the photon is ( mathrm{E} ), then
( left(lambda_{1} / lambda_{2}right) ) is proportional to:
( mathbf{A} cdot E^{4} )
B. ( E^{1 / 2} )
c. ( E^{2} )
D. ( E )
12
262Work function of three metals ( A, B, C ) are
( 4.5 mathrm{eV}, 4.3 mathrm{eV} ., 3.5 ) ev respectively. If a light of wavelength 4000 A is incident on the metals, then
A. photoelectron are emitted from ( c )
B. photoelectrons are emitted from A
c. photoelectrons are emitted from B
D. photoelectron will not emitted from all the surfaces
12
263An electron and a photon have same wavelength of ( 10^{-9} mathrm{m} . ) If ( mathrm{E} ) is the energy
of the photon and p is the momentum of the electron, the magnitude of E/p in ( mathrm{S} ) units is?
A. ( 1.00 times 10^{-9} )
B. ( 1.50 times 10^{8} )
c. ( 3.00 times 10^{8} )
D . ( 1.20 times 10^{7} )
12
264Calculate the de Broglie wavelength for a beam of electron whose energy is 100
( mathrm{eV}: )
( A cdot 1 A )
B. 1.23 A
c. ( 2.46 mathrm{A} )
D. None of these
12
265A proton, a neutron, an electron and an
( alpha ) -particle have same energy. Then their de Broglie wavelengths compare as:
( mathbf{A} cdot lambda_{p}=lambda_{n}>lambda_{e}>lambda_{alpha} )
B . ( lambda_{alpha}<lambda_{p}=lambda_{n}<lambda_{e} )
( mathbf{c} cdot lambda_{e}lambda_{alpha} )
( mathbf{D} cdot lambda_{e}=lambda_{p}=lambda_{n}=lambda_{alpha} )
12
266When the light of frequency ( 2 v_{0} ) (where
( v_{0} ) is threshold frequency), is incident
on a metal plate, the maximum velocity
of electrons emitted is ( v_{1} ). When the
frequency of the incident radiation is
increased to ( 5 v_{0}, ) the maximum velocity
of electrons emitted from the same
plate is ( v_{2} ). The ratio of ( v_{1} ) to ( v_{2} ) is?
A . 4: 1
B. 1: 2
c. 2: 1
D. 1: 4
12
267Uncertainty in position of a 0.25 g particle is ( 10^{-5} mathrm{m} . ) The uncertainty in its
velocity will be:-
( left(h=6.6 times 10^{-34} J sright) )
A. ( 1.2 times 10^{34} )
B . ( 2.1 times 10^{-29} )
c. ( 1.6 times 10^{-20} )
D. ( 1.7 times 10^{-9} )
12
268Which one of the following is not dependent on the intensity of incident photon in a photoelectric experiment?
A. work function of the surface
B. kinetic energy of photo-electron
c. stopping potential
D. amount of photo-electric current
12
269A particle A with a mass ( m_{A} ) is moving
with a velocity v and hits a particle B of
mass ( m_{B} ) at rest. If motion is one
dimensional and take the collision is
elastic, then the change in the de Broglie wavelength of the particle A is
( ^{text {A }} frac{h}{2 m_{A} v}left[frac{left(m_{A}+m_{B}right)}{left(m_{A}-m_{B}right)}-1right] )
в. ( frac{h}{m_{A} v}left[frac{left(m_{A}-m_{B}right)}{left(m_{A}+m_{B}right)}-1right] )
c. ( frac{h}{m_{A} v}left[frac{left(m_{A}+m_{B}right)}{left(m_{A}-m_{B}right)}-1right] )
D.
[
frac{2 h}{m_{A} v}left[frac{left(m_{A}+m_{B}right)}{left(m_{A}-m_{B}right)}+1right]
]
12
270(
WC
U11 IIDU
36. In Q. 32, if the wavelength is changed to 4000 A, then
stopping potential will become
(a) 1.3 V
(b) 3.40 V
(c) 1.60 V
(d) 1.97 V
12
271A parallel beam of monochromatic light
of wavelength ( 663 mathrm{nm} ) is incident on a
totally reflecting plane mirror. The angle
of incident is ( 60^{circ} ) and the number of
photons striking the mirror per second
is ( 1.0 times 10^{19} . ) If the force exerted by light
beam on the mirror is ( Y times 10^{-8} N . ) Find
( Y )
12
272An electron microscope uses electrons accelerated by a voltage of ( 50 mathrm{kV} ) Determine the de-Broglie wavelength associated with the electrons. Taking
other factors, such as numerical
aperture etc. to be same, how does the resolving power of an electron microscope compare with what of an
optical microscope which uses yellow light?
12
273The value of ( left(n_{2}+n_{1}right) ) and ( left(n_{2}^{2}-n_{1}^{2}right) ) for
( H e^{+} ) ion in atomic spectrum are 4 and 8 respectively. The wavelength of emitted photon when electron jump
from ( n_{2} ) to ( n_{1} ) is:
( ^{mathbf{A}} cdot frac{32}{9} R_{H} )
в. ( frac{9}{32} R_{H} )
c. ( frac{9}{32 R_{H}} )
D. ( frac{32}{9 R_{H}} )
12
274A particle of mass ( mathrm{M} ) at rest decays into
two masses ( m_{1} ) and ( m_{2} ) with non-zero
velocities. The ratio ( lambda_{1} / lambda_{2} ) of de Broglie
wavelengths of particles is
A ( cdot m_{2} / m_{1} )
в. ( m_{1} / m_{2} )
c. ( sqrt{m_{1}} / sqrt{m_{2}} )
in
D. 1:
12
275The work function of a surface of a
photosensitive material is ( 6.2 e V . ) The wavelength of the incident radiation for
which the stopping potential is ( 5 V ) lies in the:
A. ultraviolet region
B. ( X ) -ray region
c. infrared region
D. none of these
12
276If ( 10,000 V ) are applied across an ( X ) -ray tube, find the ratio of wavelength of the incident electrons and the shortest
wavelength of ( X ) -ray coming out of the X-ray tube, given ( e / m ) of electron ( = ) ( 1.8 times 10^{11} C k g^{-1} )
( mathbf{A} cdot 1: 10 )
B. 10: 1
c. 5: 1
D. 1: 5
12
277An isotropic point source emits light with wavelength 500nm. The radiation
power of the source is ( boldsymbol{P}=mathbf{1 0} boldsymbol{W} ). Find
the number of photons passing through unit area per second at a distance of
( 3 m ) from the source
A ( .5 .92 times 10^{17} / m^{2} s )
B . ( 2.23 times 10^{17} / m^{2} s )
c. ( 2.23 times 10^{18} / m^{2} s )
D. ( 5.92 times 10^{18} / m^{2} s )
12
278A proton is fired from very far away towards a nucleus with charge ( Q=120 mathrm{e} ) where e is the electronic charge. It makes a closest approach of ( 10 mathrm{fm} ) to the nucleus. The de Broglie wavelength (in units of ( mathrm{fm} ) ) of the proton at its start is :
(take the proton mass, ( boldsymbol{m}_{boldsymbol{p}}=(mathbf{5} / mathbf{3}) times )
( 10^{-27} k g ) and
( boldsymbol{h} / boldsymbol{e}=mathbf{4 . 2} times mathbf{1 0}^{-15} boldsymbol{J} . boldsymbol{s} / boldsymbol{C} ; frac{1}{4 pi epsilon_{0}}=mathbf{9} times )
( left.mathbf{1 0}^{9} boldsymbol{m} / boldsymbol{F} ; mathbf{1} boldsymbol{f} boldsymbol{m}=mathbf{1 0}^{-mathbf{1 5}} boldsymbol{m}right) )
( A cdot 7 f m )
B. 8 fm
( c .9 f m )
D. ( 10 mathrm{fm} )
12
279(a) More than 6.8 eV
56. A cesium photocell, with a steady potential difference of
60 V across it, is illuminated by a small bright light placed
1 m away. When the same light is placed 2 m away, the
electrons crossing the photocell
(a) each carry one-quarter of their previous momentum
(b) each carry one-quarter of their pervious energy
(c) are one-quarter as numerous
(d) are half as numerous
12
280A proton when accelerated through a potential difference of ( V ) volt has a wavelength ( lambda ) associated with it. An ( alpha )
particle in order to have the same
wavelength ( lambda ) must be accelerated
through a p.d. of
A. ( vee / 8 ) volt
B. V/4 volt
c. v volt
D. 2v volt
12
281The equation for a wave travelling in ( x ) direction on a string is : ( y=3(sin 3.14 x- )
( 314 t), ) then

Find the maximum velocity of particle
of the string.

12
282A monochromatic beam of
intensity of ( 1 W / m^{2} . ) Then the average
number of photons per ( m^{3} ) for a ( 10 mathrm{MeV} )
( gamma ) ray is ( ? )
A . 4166
B. 3000
c. 5000
D. 2083
12
283Electrons used in an electron
microscope are accelerated by a voltage of ( 25 mathrm{kV} ). If the voltage is increased to ( 100 mathrm{kV} ) then the de-Broglie wavelength associated with the electrons would?
A. Increase by 2 times
B. Decrease by 2 times
c. Decrease by 4 times
D. Increase by 4 times
12
284If the ionization energy for the hydrogen atom is ( 13 e V ), the energy required to excite it from the ground state to the next higher state is nearly
A . ( 3.4 e V )
B. ( 10.2 e V )
c. ( 12.1 e V )
D. ( 1.5 e V )
12
285Find the kinetic energy of this electron
as it comes out of the metal
A. 0.46 ev
B. 0.31 ev
( c cdot 0.23 mathrm{ev} )
D. None of these
12
286On a photosensitive material, when frequency of incident radiation is increased by ( 30 % ) kinetic energy of emitted photo electrons increases from
( 0.4 e V ) to ( 0.9 e V . ) The work function of
the surface is :
A. ( 1 e V )
B. 1.267 eV
c. ( 1.4 e V )
D. 1.8 eV
12
287Assertion
Threshold wavelength of certain metal
is ( lambda_{0} . ) Light of wavelength slightly less
than ( lambda_{0} ) is incident on the plate. It is
found that after some time the
emission of electrons stops
Reason
The ejected electrons experience force
of attraction due to development of
positive.
A. Assertion is incorrect but Reason is correct
B. Both Assertion and Reason are correct and Reason is not the correct explanation for Assertion.
C. Assertion is correct but Reason is incorrect
D. Both Assertion and Reason are incorrect and Reason is correct explanation for Assertion.
12
28875. An electron beam accelerated from rest through a potential
difference of 5000 V in vacuum is allowed to impinge on
a surface normally. The incident current is mA and if the
electrons come to rest on striking the surface the force on
it is
(a) 1.1924 x 10-ⓇN (b) 2.1 x 10-8N
(c) 1.6 × 10-N (d) 1.6 × 10-N O
12
289Which wavelength of light has the LOWEST frequency?
( mathbf{A} cdot 2 m m )
B. ( 1 n m )
c. ( 10 n m )
D. ( 20 n m )
12
290A voltage of ( 1.1 mathrm{V} ) is needed to stop the
photocurrent generated when a monochromatic light of wavelength
( lambda=4000 A ) is incident on it. Find the
work function of metal
( A cdot 2.3 mathrm{ev} )
B. 2 ev
c. 4.2 ev
D. None pf these
12
291An element undergoes reaction as shown:
( X+2 e-, ) energy released ( = )
( 30.87 e V / ) atom. If the energy released,
is used to dissociate 4 g of ( boldsymbol{H}_{2} )
molecules, equally into ( boldsymbol{H}^{+} ) and ( boldsymbol{H}^{*} )
where ( boldsymbol{H}^{*} ) is excited state of ( mathrm{H} ) atoms,
where the electrons travels in in orbit
whose circumference equal to four times it’s de Broglie’s wavelength.
Determine the least moles of ( X ) that
would be required:

Given: I.E. of ( mathrm{H}=13.6 mathrm{eV} / ) atom, bond
energy of ( boldsymbol{H}_{2}=mathbf{4 . 5 2 6 e V} / ) molecule
A . 1
B. 2
( c .3 )
D. 4

12
292ILLUSTRATION 28.1 Calculate the number of photons emitted
in 10 h by a 60 W sodium lamp (a = 5893 Å).
ho
12
293The energy of a photon is ( 3 times 10^{-12} )
ergs. Its wavelength (in nm) will be:
A .662
в. 1324
c. 66.2
D. 6.62
12
294ILLUSTRATION 28.8 What is the energy in eV) of a photon of
wavelength 12400 Å?
12
295What is the de-broglie wavelength for the electron of third class of hydrogen?
( mathbf{A} cdot 9.96 times 10^{-10} mathrm{cm} )
В. ( 9.96 times 10^{-8} mathrm{cm} )
( mathbf{c} .9 .96 times 10^{4} mathrm{cm} )
D. ( 9.96 times 10^{8} mathrm{cm} )
12
296Assertion
In both radio activity and photoelectric effect electrons may be ejected.
Reason
In photoelectric effect and radio activity emission occurs only of unstable elements.
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. Both Assertion and Reason are incorrect
12
297An electron (mass ( boldsymbol{m} ) ) with initial
velocity ( vec{v}=v_{0} hat{i}+v_{0} hat{j} ) is an electric
field ( vec{E}=-E_{0} hat{k} . ) If ( lambda_{0} ) is initial de-
Broglie wave length at time ( t ) is given by
( A )
[
frac{lambda_{0}}{sqrt{1+frac{e^{2} E^{2} t^{2}}{2 m^{2} v_{0}^{2}}}}
]
в.
[
frac{lambda_{0} sqrt{2}}{sqrt{1+frac{e^{2} E^{2} t^{2}}{m^{2} v_{0}^{2}}}}
]
c.
[
frac{lambda_{0}}{sqrt{2+frac{e^{2} E^{2} t^{2}}{m^{2} v_{0}^{2}}}}
]
D.
[
frac{lambda_{0}}{sqrt{1+frac{e^{2} E_{0}^{2} t^{2}}{m^{2} v_{0}^{2}}}}
]
12
298Electron and proton are accelerated through one volt of potential difference, the ratio of their wavelengths is equal
to:
A. ( frac{m_{p}}{m_{e}} )
В ( cdot frac{m_{p} V_{e}}{m_{e} V_{p}} )
c. ( frac{m_{p}^{2}}{m_{e}^{2}} )
D. ( sqrt{frac{m_{p}}{m_{e}}} )
12
299De-Broglie wavelength of an atom at absolute temperature ( boldsymbol{T} boldsymbol{K} ) will be
A ( cdot frac{h}{sqrt{3 m K T}} )
в. ( frac{h}{m K T} )
c. ( frac{sqrt{2 m K T}}{h} )
D. ( sqrt{2 m K T} )
12
300Graph is plotted between maximum
kinetic energy of electron with frequency of incident photon in Photo electric effect. The slope of curve will be
A. Charge of electron
B. Work function of metal
c. Planck’s constant
D. Ratio of planck constant and charge of electron
12
301A light of wavelength ( lambda ) is incident on
a metal sheet of work function ( phi=2 e V )
The wavelength ( lambda ) varies with time as
( lambda=3000+40 t, ) where ( lambda ) is in and ( t ) is in
second. The power incident on metal sheet is constant at 100 W. This signal is switched on and off for time intervals
of 2 minutes and 1 minute respectively.
Each time the signal is switched on, the
( lambda ) start from an initial value of ( 3000 . ) The
metal plate is grounded and electron clouding is negligible. The efficiency of photoemission is ( 1 %(h c=12400 e V) )
The time after which photo-emission will stop is
A. 79 s
B. 80 s
c. ( 81 mathrm{s} )
D. 78 s
12
302Find the value of wave number ( (bar{V}) ) in
term of Rydberg’s constant ( left(R_{H}right), ) when transition of electron takes place
between two levels of ( H e^{+} ) ion, whose
sum is 4 and difference is 2
A ( cdot frac{8}{9} R_{H} )
В . ( frac{32}{9} R_{H} )
c. ( frac{1}{9} R_{H} )
D. none of these
12
30357. An image of the sun is formed by a lens of the focal length
of 30 cm, on the metal surface of a photoelectric cell and
a photoelectric current/is produced. The lens forming the
image is then replaced by another of the same diameter
but of focal length 15 cm. The photoelectric current in
this case is
(c) 27
(d) 41
12
304A surface has work function ( 3.3 e V )
Which of the following will cause
emission?
A. ( 100 W ) incandascent lamp
B. 40 ( W ) flouroscent lamp
c. ( 20 W ) sodium lamp
D. 20 ( W ) Hg lamp
12
305If the kinetic energy of the particle is increased to 16 times previous the percentage change in the deBrogille wavelength of the particle is12
306If the uncertainty in the position of proton is ( 6 times 10^{-8} m, ) then the
minimum uncertainty in its speed will
be:
A ( cdot 1 mathrm{cms}^{-1} )
В. ( 0.52 mathrm{ms}^{-1} )
( mathbf{c} cdot 1 mathrm{mms}^{-1} )
D. ( 100 mathrm{ms}^{-1} )
12
30710. Two metallic plates A and B, each of area 5 x 104 m2
placed parallel to each other at a separation of 1 cm Plo
B carries a positive charge of 33.7 pc. A monochromatic
beam of light, with photons of energy 5 eV each, start
falling on plate A at t=0, so that 10’° photons fall on it per
square meter per second. Assume that one photoelectron
is emitted for every 10° incident photons. Also assume
that all the emitted photoelectrons are collected by plate
B and the work function of plate A remains constant at the
value 2 eV. Electric field between the plates at the end of
10 seconds is
(a) 2 x 10′ N/C (b) 103 N/C
(c) 5 x 10′ N/C (d) Zero
12
308In photoelectric effect, the photoelectric current is independent of
A. intensity of incident light
B. potential difference applied between the two electrodes
c. the nature of emitter material
D. frequency of incident light
12
309Assertion
The de-Broglie wavelength equation has significant for any microscopic and submicroscopic particles.
Reason
de-Broglie wavelength is inversely proportional tot he mass of the object, if its velocity is constant.
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. Both Assertion and Reason are incorrect
12
310The work function of a substance is
4.0eV. The longest wavelength of light that can cause photoelectron emission from this substance is approximately
A . ( 5400 A^{circ} )
в. ( 4000 A^{circ} )
c. ( 3100 A^{circ} )
D. 2200A ( ^{text {0 }} )
12
311The work function for tungsten and
sodium are ( 4.5 e V ) and ( 2.3 e V )
respectively. If threshold wavelength ( lambda ) for sodium is ( 5460 A ), the value of ( lambda ) for
tungsten is
( mathbf{A} .5893 hat{A} )
в. 10683 ,
c. 2791 ,
D. 528 月
12
312Light of wavelength ( lambda ) falls on a metal
having work function ( h c / lambda_{0} )

Photoelectric effect will take place only if
( A cdot lambda geq lambda_{0} )
в. ( lambda geq 2 lambda_{0} )
c. ( lambda leq lambda_{0} )
D. ( lambda<lambda_{0} / 2 )

12
313Calculate the de Broglie wavelength associated with a helium atom in a
helium gas sample at ( 27^{circ} mathrm{C} ) and 1 at ( mathrm{m} )
pressure.
( mathbf{A} cdot 7.3 times 10^{-11} ) metre.
B . ( 3.6 times 10^{-10} ) metre.
c. ( 7.3 times 10^{-10} ) metre.
D. ( 3.6 times 10^{-11} ) metre.
12
31454. Ultraviolet light of wavelength 300 nm and intensity
1.0 Wm falls on the surface of a photosensitive material.
If one per cent of the incident photons produce photo-
electrons, then the number of photoelectrons emitted per
second from an area of 1.0 cm of the surface is nearly
(a) 9.61 x 1014 s-1
(b) 4.12 x 10135-1
(c) 1.51 x 1012 5-1
(d) 2.13 x 1011 3-1
12
315An electron of mass ‘m’ and charge ‘w’ initially at rest gets accelerated by a constant electric field ‘E’. The rate of
change of de-Broglie wavelength of this electron at time ‘t’ ignoring relativistic effects is
( ^{A} cdot-frac{h}{e E t^{2}} )
B. ( -frac{e h t}{E} )
c. ( -frac{m h}{e E t^{2}} )
D. ( frac{h}{e E} )
12
316A particle having a mass of 1.0 mg has
a velocity of ( 3600 k m / h ). Calculate the wavelength of the particle:
( left(h=6.626 times 10^{-27} e r g-s e cright) )
A ( cdot 6.626 times 10^{-28} mathrm{cm} )
B. ( 6.626 times 10^{-29} mathrm{cm} )
C. ( 6.626 times 10^{-30} mathrm{cm} )
D. ( 6.626 times 10^{-31} mathrm{cm} )
12
317In a H-atom, an electron is in ( 2^{n d} ) excited state and its radius ( =4.75 AA )
Calculate de-broglie wavelength of the electron.
A ( cdot frac{8.5 pi}{4} )
B. 0
с. ( frac{19 pi}{3} ),
D. ( frac{9.5 pi}{3} )
12
318A photon and electron have got the same de Broglie wavelength. Explain
which has greater total energy.
12
319Name the unit in which work function of
a metal is generally expressed.
A. Newton
B. Kilojoule
( c cdot e v )
( D )
12
32071. The potential energy of a particle of mass m is given bu
U(x) = {Bo; 05×51
x > 1
2, and I are the de-Broglie wavelengths of the particle
when 0 <x 1 respectively. If the total energy
of particle is 2Eo, the ratio will be
(b) 1
(b) 1
blos
(a) 2
(c) 2.
12
321Photon of frequency ( boldsymbol{v} ) has a momentum
associated with it. If ( c ) is the velocity of
light, the momentum is :
( mathbf{A} cdot v / c )
B. hv ( c )
c. ( h v / c^{2} )
D. ( h v / c )
12
322An electron, ( alpha ) – particle and a proton
have the same kinetic energy. A comparison of their de Broglie wavelengths yields:
A ( cdot lambda_{p}>lambda_{a}lambda_{a}<lambda_{p} )
c. ( lambda_{a}<lambda_{p}<lambda_{e} )
D. ( lambda_{p}<lambda_{e}<lambda_{a} )
12
323If the kinetic energy of a particle is increased by 16 times, the percentage change in the de Broglie wavelength of the particle is:
A . 25%
B. 75%
c. 60%
D. 50%
12
324A photon of light from which of the following electromagnetic radiations carries the greater amount of energy?
A. Blue
B. Green
c. orange
D. Red
E. Yellow
12
325When a metal surface is illuminated by
light of wavelengths ( 400 mathrm{nm} ) and 250 ( mathrm{nm}, ) the maximum velocities of the
photoelectrons ejected are v and 2v respectively. The work function of the metal is
A ( cdot 3.972 times 10^{-19} mathrm{J} )
В. ( 1.59 times 10^{-19} mathrm{J} )
D. ( 0.5 times 10^{-19} mathrm{J} )
12
326Einstein was awarded a Noble Prize for:
A. Photo electric effect
B. Compton effect
c. Theory of relativity
D. None of the above
12
327Louis de -Broglie is credited for his work
on
A. Theory of relativity
B. Electromagnetic theory
c. Matter waves
D. Law of distribution of velocities
12
328Assertion
The photoelectrons produced by a
monochromatic light beam incident on
a metal surface, have a spread in their
kinetic energies.
Reason
The work function of the metal varies as
a function of depth from the surface.
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
329In a photo-emissive cell with exciting wavelength ( lambda ), the fastest electron has
speed ( v ). If the exciting wavelength is
changed to ( 3 lambda / 4 ) the speed of the fastest emitted electron will be :
A ( cdot v(3 / 4)^{1 / 2} )
B ( cdot v(4 / 3)^{1 / 2} )
c. less than ( v(4 / 3)^{1 / 2} )
D. greater than ( v(4 / 3)^{1 / 2} )
12
330The peak emission from a black body at a certain temperature occurs at a wavelength of 9000 A. On increasing its temperature, the total radiation
emitted is increased 81 times. At the
initial temperature when the peak radiation from the black body is
incident on a metal surface, it does not
cause any photoemission from the surface. After the increase of
temperature, the peak radiation from the black body caused photoemission. To bring these photoelectrons to rest, a potential equivalent to the excitation energy between ( n=2 ) and ( n=3 ) Bohr
levels of hydrogen atoms is required. Find the work function of the metal.
12
331If the energy and momentum of a photon are ( mathrm{E} ) and ( mathrm{p} ) respectively, then the velocity of photon will be This question has multiple correct options
A. ( frac{E}{p} )
( ^{text {В }}left(frac{E}{p}right)^{2} )
( c cdot E p )
D. ( 3 times 10^{8} mathrm{m} / mathrm{s} )
12
332A proton and ana – particle
accelerated through same voltage.The ratio of their de-broglie wavelength will
be:
A .1: 2
B . ( 2 sqrt{2}: 1 )
c. ( sqrt{2}: 1 )
D. 2: 1
12
33348. The maximum velocity of electrons emitted from a metal
surface is v. What would be the maximum velocity if the
frequency of incident light is increased by a factor of 4?
(a) 2v
(b) > 2v
(c) <2v
(d) between 2v and 4v.
5
12
334An electron of mass ( m ) and a photon
have same energy ( E . ) The ratio of de-
Broglie wavelength associated with them is:
( stackrel{mathbf{A}}{_{c}}left(frac{E}{2 m}right)^{frac{1}{2}} )
( c cdot(2 m E)^{frac{1}{2}} )
( stackrel{1}{c}left(frac{2 m}{E}right)^{frac{1}{2}} )
( (c ) being velocity of light)
12
335In a photoelectric experiment, the collector plate is at ( 2.0 mathrm{V} ) with respect to the emitter plate made of copper ( (phi= ) 4.5 ( e V ) ). the emitter is illuminated by a
source of monochromatic light of
wavelength ( 200 mathrm{nm} )
A. The minimum kinetic energy of the photo electrons reaching the collector is 0
B. The maximum kinetic energy of the photo electrons reaching collector is 3.7 ev.
c. If the polarity of the battery is reversed then answer to part A will be o
D. If the polarity of the battery is reversed then answer to part B will be 1.7 eV
12
336In a photo electric experiment, when
intensity of incident light increases:
A. photo-current increases
B. photo-current decreases
C. kinetic energy of emitted photoelectrons increases
D. kinetic energy of emitted photoelectrons decreases
12
337max
17. Statement 1: When ultraviolet light is incident on a
photocell, its stopping potential is V. and the maximum
kinetic energy of the photoelectrons is Kmax. When the
ultraviolet light is replaced by X-rays, both Vo and K.
increase.
Statement 2: Photoelectrons are emitted with speeds
ranging from zero to a maximum value because of the
range of frequencies present in the incident light.
(a) Statement 1 is true, statement 2 is true; statement 2 is
the correct explanation for statement 1.
(b) Statement 1 is true, statement 2 is true; statement 2 is
not the correct explanation for statement 1.
(c) Statement 1 is false but statement 2 is true.
(d) Statement 1 is true but statement 2 is false.
(AIEEE 2010)
20
12
33844. Work function of nickel is 5.01 eV. When ultravi.
radiation of wavelength 200 Å is incident on it, elect
are emitted. What will be the maximum velocity of emitted
electrons ?
(a) 3 x 108 m s d (b) 6.46 x 10 ms!
(c) 10.36 x 10 m 5-1 (d) 8.54 x 10ºm s-1
12
339In photoelectric effect, the momentum
of incident photon of energy ( 3 times 10^{-19} J )
is :
( mathbf{A} cdot 9 times 10^{11} mathrm{kgms}^{-1} )
B. zero
c. ( 10^{-27} mathrm{kgms}^{-1} )
D. ( 3 times 10^{-11} mathrm{kgms}^{-1} )
12
340ILLUSTRATION 29.8 An X-ray tube operates at 20 kV. Find the
maximum speed of the electrons striking the anode, given the
charge of electron is 1.6 x 10-9 coulomb and mass of electron
is 9 x 10-31 kg.
12
341Davisson Germer experiment explained the wave nature of electrons through
A. Electron diffraction
B. Electron interference
c. Electron scattering
D. Failed to explain wave nature of electrons
12
342An electron in an atom absorbs
radiation of wavelength ( 392 . n . m ) and later on it emits energy in the from of photons of two different wavelengths. If one of the wavelength is 712 n.m.
Calculate the other
12
343Fill in the blanks:
The ( ldots ) tungsten is reduced by coating with barium oxide.
A. Normal function
B. Force function
c. Power function
D. Work function
12
344The de-Broglie wavelength of electron in
( 3^{r d} ) orbit of ( H e^{+1} ) ion is approximately
( mathbf{A} cdot 2 A^{0} )
B. ( 3 A^{circ} )
c. ( 4 A^{circ} )
D. ( 5 A^{circ} )
12
345The circumstance of first of hydrogen
atom is s.Then the Broglie wavelength of electron to that orbit is
A ( cdot frac{S}{2} )
в. ( 2 S )
( c . s )
D. ( 3 S )
12
346The work function of a metal surface is 1
eV. A light of wavelength ( 3000 A^{0} ) is incident on it. The maximum velocity of the photo-electrons is nearly
( mathbf{A} cdot 10^{6} m s^{-1} )
B . ( 10^{4} m s^{-1} )
c. ( 10^{2} m s^{-1} )
D. ( 10 m s^{-1} )
12
34712. In the following diagram if V, > V, then
(Photoelectric
current)
V2 V, Potential
difference
(2) n = siz
(c) 2 = 2
(b) 2,
12
348After absorbing a slowly moving
neutron of Mass ( m_{N} ) (momentum ( approx 0 ) )
a nucleus of mass M breaks into two
nuclei of masses ( boldsymbol{m}_{1} ) and ( mathbf{5 m}_{mathbf{1}}left(boldsymbol{6} boldsymbol{m}_{mathbf{1}}=right. )
( left.M+boldsymbol{m}_{N}right) ) respectively. If the de Broglie
wavelength of he nucleus with mass ( m_{1} )
is ( lambda, ) the de Broglie wavelength of the
nucleus will be.
A ( .5 lambda )
B. ( lambda / 5 )
( c cdot lambda )
D. ( 25 lambda )
12
349Radiation from hydrogen gas excited to first excited state is used for
illuminating certain photoelectric plate. When the radiation from some unknown
hydrogen-like gas excited to the same level is used to expose the same plate, it is found that the de Broglie wavelength of the fastest photoelectron has decreased 2.3 times. It is given that the energy corresponding to the longest wavelength of the Lyman series of the unknown gas (13.6 eV). Find the work function of the photoelectric plate in eV.
( left[text { take }(2.3)^{2}=5.25right] )
12
350The energy of a photon of light with wavelength ( 5000 A ) is approximately ( 2.5 e V . ) This way the energy of an X-ray
photon with wavelength ( 1 A ) would be:
A. ( frac{2.5}{(5000)^{2}} e V )
в. ( 2.5 times 5000 ) eV
c. ( frac{25}{(5000)^{2}} cdot e V )
D. ( frac{2.5}{5000} e V )
12
351The wavelength of a matter wave is
given by
A. Heisenberg’s hypothesis
B. Bohr’s principle
c. Debroglie’s rule
D. Newton-laplace rule
12
352Threshold wavelength of tungsten is 2300 angstrom. If ultraviolet light of wavelength 1800 angstrom is incident on it, then the maximum kinetic energy of photoelectrons would be?
A . 1.5 ev
B. 2.5ev
c. 3.0 ev
D. ( 5.0 mathrm{eV} )
12
353The minimum heat energy required to emit an electron from the surface of a
metal is called
A. Extracting function
B. Work function
C. Threshold energy
D. None of the above
12
354If ( h ) is Plancks constant, the
momentum of a photon of wavelength
( 0.01 A^{circ} ) is
( mathbf{A} cdot 10^{-2} h )
B. ( h )
( c cdot 10^{2} )
D. ( 10^{12} h )
12
355A photon of energy 2.5 eV and
wavelength ( ^{prime} lambda^{prime} ) falls on a metal surface
and the ejected electrons have
maximum velocity ‘ ( v^{prime} . ) If the ( ^{prime} lambda^{prime} ) of the
incident light is decreased by ( 20 % ), the maximum velocity of the emitted electrons is doubled. The work function
of the metal is :
A . 2.6 ev
B. 2.23 ev
c. 2.5 ev
D. 2.29 ev
12
356Determine de-Broglie wavelength of an
electron having kinetic energy of ( 1.6 times ) ( 10^{-6} ) erg.
A ( .12 .42 A^{circ} )
B. ( 12.42 mathrm{cm} )
c. ( 12.42 m )
D. none of these
12
357The number of photons falling per second on a completely darkened plate
to produce a force of ( 6.62 times 10^{-5} mathrm{N} ) is ‘n’
If the wavelength of the light falling is ( 5 times 10^{-7} m, ) then ( n=_{-1-}—times 10^{22} )
( left(h=6.62 times 10^{-34} J-sright) )
A . 1
B. 5
( c .0 .2 )
D. 3.3
12
358How does one explain the emission of electrons from a photosensitive surface with the help of Einstein’s photoelectric equation?12
359Calculate the momentum of particle
whose de Broglie wavelength is ( 2^{circ} A )
A ( cdot 3.313 times 10^{-24} g m s^{-1} )
В. ( 3.313 times 10^{-24} k g m s^{-1} )
c. ( 33.13 times 10^{-20} k g m s^{-1} )
D. none of these
12
360The work functions of lithium and
copper are ( 2.3 e V ) and ( 4.0 e V )
respectively. Out of these, the one which is suitable for the photoelectric cell that works with the visible light is
A. lithium
B. copper
c. both lithium and copper
D. neither lithium nor copper.
12
361What is photoelectric effect? Explain the effect of increase
(i) frequency (ii) intensity of incident radiation on photoelectric current with suitable graphs.
12
362The energy of photon of visible light with maximum wavelength in ( e V ) is:
( mathbf{A} cdot mathbf{1} )
в. 1.6
( c .3 .2 )
D.
12
363The energy of an electron of mass ( m ) moving with velocity ( mathrm{V} ) and de-Broglie wavelength ( lambda ) is (‘h’ is
Planck’s constant)
A ( cdot frac{h}{2 m lambda} )
в. ( frac{h^{2}}{2 m lambda^{2}} )
c. ( frac{h lambda}{2 m} )
D. ( frac{h}{m lambda} )
12
364Find the frequency of photon.
A ( cdot 2.71 times 10^{14} mathrm{Hz} )
в. 2.01 ( times 10^{14} mathrm{Hz} )
c. ( 2.5 times 10^{14} H z )
D. 20.1 ( times 10^{14} mathrm{Hz} )
12
365What is the momentum of a photon if
the wavelength of X-rays is 1 angstrom?
12
3667. The potential energy of a particle of mass m is given by
Eo; OSx51
U(x)=
(0; x>1
2, and I are the de Broglie wavelengths of the particle,
when 0 SX S1 and x > 1 respectively. If the total energy
of particle is 2Eo, the ratio 1 will be
2
(a) 2
(b) 1
(c) V2
12
367A parallel beam of electrons travelling
in x-direction falls on a slit of width d. If
after passing the slit, an electron
acquires momentum ( p_{y} ) in the ( y )
direction, then for a majority of electrons passing through the slit (h is Planck’s constant).
( mathbf{A} cdotleft|P_{y}right| d>h )
( mathbf{D} cdotleft|P_{y}right| d>h )
12
368A metal is irradiated with light of
wavelength ( 600 n m . ) Given that the work
function of the metal is ( 1.0 e V ), the de
Broglie wavelength of the ejected electron is close to:
A ( cdot 6.6 times 10^{-7} mathrm{m} )
в. ( 8.9 times 10^{-11} ) ( _{m} )
c. ( 1.3 times 10^{-9} m )
D. ( 6.6 times 10^{-13} ) и
12
369An alpha particle moving with an initia velocity ( (u j) ) enters a region of uniform
magnetic field ( B=B k ). the de-Broglie
wavelength of the alpha particle.
A. Increases to a higher constant value
B. Decreases to a lower constant value
c. Increases and decreases periodically
D. Remains constant
12
370( 10^{-3} W ) of ( 5000 A ) light is directed on a
photoelectric cell. If the current in the cell is ( 0.16 mu A ), the percentage of incident photons which produce photoelectrons, is
A . ( 40 % )
B . 0.04%
c. 20%
D. 10%
12
371How can photoelectric effect be used to produce electricity12
372ILLUSTRATION 28.3 A source of light of power P is shown in
figure. Find the force
on the block placed in
the path of the light
rays. The surface of
P watt
Light source
body on which the
light beam is incident is having a reflection coefficient a, = 0.7
and absorption coefficient a, = 0.3.
12
373Tungsten has work function ( 4.8 e V . ) We
wish to use tungsten as photo-cathode
with a 600 nm wavelength. What shall
we do?
A. Coat tungsten with Cesium
B. Oxide coat tungsten
c. ( C u_{2} O_{2} ) be coated on tungsten
D. None of these
12
374An electron gun with its collector at a potential of ( 100 mathrm{V} ) fires out electrons in a spherical bulb containing hydrogen gas at low pressure ( left(sim 10^{-2} mathrm{mm} text { of } mathrm{Hg} text { ). } mathrm{A}right. )
magnetic field of ( 2.83 times 10^{4} T )
curves the path of the electrons in a
circular orbit of radius 12.0 cm.
(The path can be viewed because the
gas ions in the path focus the beam by attracting electrons, and emitting light by electron capture; this method is known as the fine beam tube method.) Determine e/m from the data.
12
375The de-Broglie wavelength of a proton and alpha particle is same, the ratio of their velocities is :
A . 1: 2
B. 2:
( c cdot 1: 4 )
D. 4:
12
376Protons are accelerated from rest by a potential difference ( 4 mathrm{kV} ) and strike a
metal target. If a proton produces one photon on impact of minimum
wavelength ( lambda_{1} ) and similarly an electron accelerated to ( 4 mathrm{kV} ) strikes the target
and produces a minimum wavelength
( lambda_{2} ) then
A ( cdot lambda_{1}=lambda_{2} )
B. ( lambda_{1}>lambda_{2} )
( c cdot lambda_{1}<lambda_{2} )
D. no such relation can be established
12
377Consider a hypothetical hydrogen like
atom. The wavelength in ( A ) for the
spectral lines for transition from ( boldsymbol{n}=boldsymbol{p} )
( operatorname{ton}=1 ) are given by- ( lambda=frac{1500}{p^{2}-1} )
Where ( boldsymbol{p}=mathbf{2}, mathbf{3}, mathbf{4}, ) (given ( boldsymbol{h} boldsymbol{c}= )
( 12400 e V / A) )
This question has multiple correct options
A. The wavelength of the least energetic and the most energetic photons in this series is 2000 A, 1500 A
B. Difference between energies of fourth and this orbit is ( 0.40 mathrm{eV} )
C. Energy of second orbit is 6.2 eV
D. The ionization potential of this element is ( 8.27 V )
12
378Maximum kinetic energy of the emitted photoelectrons depends upon
A. Intensity of incident light
B. Frequency of incident light
c. Total number of photons of incident light
D. Both (2) and (3)
12
379The ratio of wavelengths of electron
waves in two orbits is ( 3: 5 . ) The ratio of
kinetic energy of electrons will be:
( mathbf{A} cdot 25: 9 )
B. 5: 3
( mathbf{c} cdot 9: 25 )
D. 3: 5
12
380A plot of the kinetic energy ( left(1 / 2 m v^{2}right) ) of
ejected electrons as a function of the frequency (v) of incident radiation for
four alkali metals ( left(M_{1}, M_{2}, M_{3}, M_{4}right) ) is
shown below:

The alkali metals ( M_{1}, M_{2}, M_{3} ) and ( M_{4} )
are respectively
A . Li, Na, K and Rb
B. Rb, K, Na and Li
C. Na, K, Li and Rb
D. Rb, Li, Na and K

12
381A heavy nucleus at rest breaks into two fragments which fly off with velocities
in the ratio ( 8: 1 . ) the ratio of de-broglie
wavelengths of fragments are
A . 1: 2
B. 1: 8
c. 4: 1
D. None of these
12
38242. The KE of the photoelectrons is E when the incident
wavelength is 1/2. The KE becomes 2E when the incident
wavelength is N3. The work function of the metal is
(a) hcl 2
(b) 2hc/2
(c) 3hc/a
(d) hc/32
12
383The work function of a certain metal is
4.2 eV. Which among the wavelengths ( 390 mathrm{nm}, 440 mathrm{nm}, 550 mathrm{nm} ) and ( 70 mathrm{nm} ) will
this metal give photoelectric emission?
A. 390 nm only
B. 390 nm, 440 nm only
( mathrm{c} .390 mathrm{nm}, 440 mathrm{nm} ) and ( 550 mathrm{nm} )
D. None of them
12
384The wavelength of an electron:
This question has multiple correct options
A. is equal to that of light
B. remains constant with velocity
C . decreases with an increasing velocity
D. increases with an decreasing velocity
12
385A student prepares a ( 0.10 M ) CoCl ( _{2} )
solution and determines the
absorbance of the solution at various
wavelengths using a
spectrophotometer. A graph of the results is shown below.

Identify the optional wavelength for
absorbance.
( mathbf{A} cdot 300 n m )
B. ( 375 n m )
( mathbf{c} cdot 410 n m )
D. ( 550 n m )

12
38640. When a centimeter thick surface is illuminated with lishe
of wavelength 2, the stopping potential is V. When
same surface is illuminated by light of wavelength 22
the stopping potential is V/3. Threshold wavelength for
the metallic surface is
(a) 41/3
(b) 42
(c) 62
(d) 82/3
12
387A photon of energy 10.2 eV corresponds
to light of wavelength ( lambda_{0} . ) Due to an electron transition from ( x=2 ) to ( x=1 ) in a
hydrogen atom, light of wavelength A is emitted. If we take into account the
recoil of the atom when the photon is
emitted, then :
( A cdot lambdalambda_{0} )
c. ( lambda=lambda_{0} )
D. None of these
12
38849. In a photocell, with excitation wavelength 2, the faster
electron has speed v. If the excitation wavelength is
changed to 3N4, the speed of the fastest electron will be
(a) V(3/4)1/2
(b) v(4/3)1/2
(c) less than v(4/3)/2
(d) greater than v(4/3)1/2
12
389A radio transmitter operates at a frequency of ( 880 mathrm{kHz} ) and power of 10 kW. The number of photons emitted per second is :
( mathbf{A} cdot 13.27 times 10^{4} )
B. ( 13.27 times 10^{3} )
c. ( 1327 times 10^{34} )
D. ( 1.71 times 10^{31} )
12
390Mention any two types of electron emission12
39143. The threshold frequency for certain metal is v. When liche
of frequency 2v, is incident on it, the maximum velo
of photoelectrons is 4 x 100 m s. If the freque
incident radiation is increased to 5 Vo, then the maximum
velocity of photoelectrons will be
(a) 4/5 x 10 m s-1
(b) 2 x 10ºm s-1
(c) 8 x 10 m s-1 (d) 2 x 10’m s-1
12
392If ( E_{1}, E_{2} ) and ( E_{3} ) are the kinetic energies
of a proton, ( alpha ) -particle and deuteron
respectively, which all have the same
wavelength, then
A ( cdot E_{1}>E_{2}>E_{3} )
в. ( E_{1}>E_{3}>E_{2} )
c. ( E_{3}>E_{2}>E_{1} )
D. ( E_{3}>E_{1}>E_{2} )
12
393After absorbing a slowly moving neutron of mass ( m_{N} ) (momentum ( sim 0 ) )
a nucleus of mass ( M ) breaks into two
nuclei of masses ( m_{1} ) and
( mathbf{5} boldsymbol{m}_{1}left(boldsymbol{6} boldsymbol{m}_{1}=boldsymbol{M}+boldsymbol{m}_{N}right) ) respectively. If
the de-Broglie wavelength of the
nucleus with mass ( m_{1} ) is ( lambda ), the de
Broglie wavelength of the other nucleus will be:
( A cdot lambda )
в. ( 25 lambda )
( c cdot 5 lambda )
D. ( lambda / 5 )
12
394A photon of energy ( mathrm{E}_{1} ) incident on a surface liberates electrons whose
energy is equal to the work function ( mathbf{W} ) of the metal. When a photon of energy
2
is incident on the same surface, energy of the emitted electrons is ( 3 mathrm{W} )
The ratio ( mathrm{E}_{1}: mathrm{E}_{2} ) is
A . 1: 2
B. 2:
c. 1: 3
D. 3:
12
395Light described at a place by the equation ( boldsymbol{E}=(mathbf{1 0 0} boldsymbol{V} / boldsymbol{M}) times[sin (mathbf{5} times )
( left.mathbf{1 0}^{mathbf{1 5}} boldsymbol{s}^{-mathbf{1}}right) boldsymbol{t}+boldsymbol{operatorname { s i n }}left(boldsymbol{8} times mathbf{1 0}^{mathbf{1 5}} boldsymbol{s}^{-mathbf{1}}right) boldsymbol{t} )
Falls on a metal surface having work function 2.0 e.V Calculate the maximum
kinetic energy of the photoelectrons
A . 3.27 ev
B. 5 ev
c. 1.27 ev
D. 2.5 ev
12
396The ratio of wavelengths of photons emitted when hydrogen atom de-excites from third excited state to second
excited state an then de-excites form
seconds excited state to first excited
state is
A ( cdot frac{7}{20} )
в. ( frac{20}{7} )
( c .5 )
D. 20
12
397The ratio of the deBroglie wave length for the electron and proton moving with same velocity is:
( left[m_{p}-text { mass of propton, } m_{e}- ) mass of right. electron]
( mathbf{A} cdot m_{p}: m_{e} )
в. ( m_{p}^{2}: m_{e}^{2} )
( mathbf{c} cdot m_{e}: m_{p} )
D. ( m_{e}^{2}: m_{p}^{2} )
12
398Which of these particles having the same kinetic energy has the largest de Broglie wavelength?
A. Electron
B. Alpha particle
c. Proton
D. Neutron
12
399The de Broglie wavelength associated with an electron of energy 500 ev is given by (take ( boldsymbol{h}=mathbf{6 . 6 3} times mathbf{1 0}^{-mathbf{3 4} mathbf{J}} boldsymbol{s}, boldsymbol{m}=mathbf{9 . 1 1} times )
( left.10^{-31} k gright) )
A ( cdot 0.28 A^{0} )
B . 1.410 ( A^{circ} )
( c cdot 0.66 A^{0} )
D. 0.55 ( A^{circ} )
12
400Davisson and Thomson shared the
Nobel Prize for their experimental discovery of diffraction of electrons by
crystals. True ( =1, ) false ( =0 )
12
401Find the maximum potential a ( boldsymbol{C u} ) ball (isolated) can have when irradiated with a wavelength ( lambda=140 n m )
( left[phi_{C u}=4.47 mathrm{eV}right] )
A . ( 4.47 V )
B. 8.86 ( V )
c. ( 13.33 V )
D. 4.39 ( V )
12
402The threshold wavelength for emission of photoelectrons from a metal surface is ( 6 times 10^{-7} mathrm{m} . ) The work function of the
material of the metal surface is :
A ( cdot 3.33 times 10^{-19} mathrm{J} )
J. ( 3.33 times 10^{-19} )
В ( cdot 6.67 times 10^{-19} mathrm{J} )
С. ( 1.23 times 10^{-19} mathrm{J} )
J ( 5 times 10^{-1.2} )
D. ( 2.37 times 10^{-19} mathrm{J} )
12
403The wavelength ( lambda_{e} ) of an electron and ( lambda_{p} )
of a photon of same energy ( boldsymbol{E} ) are
related by:
( A cdot lambda_{p} propto lambda_{e} )
B. ( lambda_{p} propto sqrt{lambda_{e}} )
c. ( lambda_{p} propto frac{1}{sqrt{lambda_{e}}} )
D. ( lambda_{p} propto lambda_{e}^{2} )
12
404An electron is moving in ( 2^{n d} ) excited orbit of H-atom Radius of orbit in terms
of de-Broglie wavelength ( lambda ) of electron can be given as
( A cdot frac{lambda}{pi} )
в. ( frac{2 lambda}{pi} )
c. ( frac{3 lambda}{2 pi} )
D. ( frac{lambda}{2 pi} )
12
405When an electron falls from ( 2^{n d} ) energy
level to ground state then which of the following will produce shortest
wavelength?
A ( cdot B e^{3+} ) ion
B. ( D ) -atom
c. ( H- ) atom
D. ( H e^{+} ) ion
12
406The circumference of the second Bohr
orbit of electron in the hydrogen atom is
( 600 n m . ) Calculate the potential
difference to which the electron has to
be subjected so that the electron stops. The electron had the de Broglie
wavelength corresponding to the circumference.
12
40713. Two electrons are moving with same speed v. One electro
enters a region of uniform electric field while the other
enters a region of uniform magnetic field, then after
some time de Broglie wavelengths of two are 2, and 2
respectively. Now,
(a) 11 = ,
(b) 2,>
(c) 2,<
(d) 2, can be greater than or less than ,
12
408(c) 2X 10
(0) 1.07 10
6. An electron of mass m, and a proton of mass m, are
accelerated through the same potential difference. The
ratio of the de Broglie wavelength associated with an
electron to that associated with proton is
(a) 1
(b) melme
(c) m/m
(d) m ime
12
409Assertion
In photoelectron emission the velocity of electron ejected from near the surface is larger than that coming from interior of metal.
Reason
The velocity of ejected electron will be
zero
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. If Assertion is incorrect but Reason is correct
12
410Define the following in photoelectric effect phenomenon:
(a) (i) Work function
(ii) Stopping potential (cut-off potential)
(b) Calculate energy of photon of wavelength ( 3.31 A )
12
411What is the wavelength of light emitted when the electron in a hydrogen atom undergoes a transition from an energy
level with ( n=4 ) to an energy level with
( boldsymbol{n}=mathbf{2} ? )
A ( .5654 A^{circ} )
B. ( 3852 A^{circ} )
( mathbf{c} cdot 4920 A^{circ} )
D. ( 4852 A^{circ} )
12
412De Broglie wavelength of neutrons in
thermal equilibrium is (given ( boldsymbol{m}_{boldsymbol{n}}= )
( left.1.6 times 10^{-27} k gright) )
A ( cdot 30.8 / sqrt{T}_{A}^{circ} )
B ( cdot 3.08 / sqrt{T}_{A}^{o} )
c. ( 0.308 / sqrt{T}_{A}^{circ} )
D ( cdot 0.0308 / sqrt{T}^{circ} )
12
41331. A proton when accelerated through a potential difference
of V volt has a wavelength 2 associated with it. An
Ol-particle in order to have the same 2 must be accelerated
through a potential difference of
(a) V volt
(b) 4V volt
(c) 2V volt
(d) (V/8) volt
12
414The work function of a substance is 4.0
eV. The longest wavelength of light that can cause photo electron emission from this substance is approximately:
A. ( 540 mathrm{nm} )
B. 440 nm
( c .310 mathrm{nm} )
D. 220 nm
12
41521. Statement 1: Davisson-Germer experiment established
the wave nature of electrons.
Statement 2: If electrons have wave nature, they can
interfere and show diffraction.
(a) Statement 1 is false but statement 2 is true.
(b) Statement 1 is true but statement 2 is false
(c) Statement 1 is true, statement 2 is true, statement 2 is
the correct explanation for statement 1
(d) Statement 1 is true, statement 2 is true, statement 2 is
not the correct explanation of statement 1
(AIEEE 2012)
12
416If the momentum of an electron is
changed by ( p_{m}, ) then the de Broglie wavelength associated with it
increased by ( 0.5 % ). The initial momentum of electron will be
A ( cdot p_{m} / 200 )
в. ( p_{m} / 100 )
c. ( 201 p_{m} )
D. ( 100 p_{m} )
12
417The work function of the following metals is given: ( N a=2.75 e V, K= )
( mathbf{2 . 3} e V, M o=4.17 e V ) and ( N i= )
( 5.15 e V . ) Which of these metals will not
undergo photoelectric emission for
radiation of wavelength ( 3300 A ) from a
laser source placed 1 m away from these metals? What happens if the
laser source is brought closer and
placed ( 50 mathrm{cm} ) away?
12
418A particle of mass ( mathrm{M} ) at rest decays into
two particles of masses ( m_{1} ) and ( m_{2} )
having non zero velocities. The ratio of the de Broglie wavelengths of the
particles, ( lambda_{1} / lambda_{2} ) is?
12
4195. The ratio of de Broglie wavelength of a a-particle to that
of a proton being subjected to the same magnetic field
so that the radii of their paths are equal to each other
assuming the field induction vector B is perpendicular to
the velocity vectors of the a-particle and the proton is
(a) 1
(b)
(d) 2
12
4208. If no stands for mid-wavelength in the visible region, the
de Broglie wavelength for 100 V electrons is nearest to
(a) 20/5
(b) 20/50
(c) 20/500
(d) 20/5000
L
L
.
11.cc
12
42168. The kinetic energy of a particle is equal to the enerov
a photon. The particle moves at 5% of the speed of light
The ratio of the photon wavelength to the de Broglie
wavelength of the particle is
[No need to use relativistic formula for the particle.
(a) 40
(b) 4
(c) 2
(d) 80
12
422Wavelength associated with an electron
having kinetic energy ( 3 times 10^{-25} J ) is
( x times 10^{-7} ) m. What is the value of ( x ? )
( A cdot 9 )
B. 4
( c .5 )
D. 6
12
423Work function of a metal is the:
A. Energy required by an electron to get absorbed in the metal surface.
B. Minimum energy required by an electron to escape from the metal surface.
C. Energy required by an electron to be retained in the metal surface.
D. Maximum energy required by an electron to escape from the metal surface.
12
424A modern 200 W sodium street lamp
emits yellow light of wavelength ( 0.6 mu m ) Assuming it to be ( 25 % ) efficient in converting electrical energy to light, the number of photons of yellow light it emits per second is :
A ( cdot 62 times 10^{20} )
B . ( 3 times 10^{19} )
c. ( 1.5 times 10^{20} )
D. ( 6 times 10^{18} )
12
4259. In a photocell, bichromatic rays of light of wavelength
2475 Å and 6000 Å are incident on cathode whose work
function is 4.8 eV. If a uniform magnetic field of 3 x 10-5
tesla exists parallel to the plate, the radius of the path
describe by the photoelectron will be (mass of electron
= 9 x 10-31 kg)
(a) 1 cm
(b) 5 cm
(c) 10 cm
(d) 25 cm
12
426The de Broglie wavelength of a tennis ball of mass 60 g moving with a velocity of ( 10 mathrm{m} / mathrm{sec} ) is approximately:
A. ( 10^{-33} mathrm{m} )
.
В . ( 10^{-31} mathrm{m} )
c. ( 10^{-16} mathrm{m} )
.
D. ( 10^{-25} mathrm{m} )
12
427In an experiment on photoelectric effect, Light of wavelength 800 nm (less than threshold wavelength) is incident
on a cesium plate at the rate of ( 5.0 mathrm{W} ) The potential of the collector plate is made sufficiently positive with respect on the emitter so that the current
reaches its saturation value. Assuming
that on the average one of every ( 10^{6} )
photons is able to eject a photoelectron,
find the photo current in the circuit.
12
428The wavelength associated with 1 Me ( V )
proton is
A. ( 28.6 p m )
B. 2.86 ( p m )
c. ( 2.86 mathrm{fm} )
D. 28.6 ( f m )
12
429When a surface is irradiated with light
of wavelength ( 4950, ) a photocurrent appears which vanishes if a retarding
potential greater than ( 0.6 ~ V ) is applied across the phototube. When different source of light is used, it is found that the critical retarding potential is changed to ( 1.1 mathrm{V} ). Find the work function of the emitted surface and the
wavelength of the second source.
12
430The important conclusion given by Millikan’s experiment about the charge
is
A. Charge is never quantised
B. Charge has no definite value
c. Charge is quantised
D. Charge on an oil drop always increases
12
431De-Broglie wavelength depends on
A. Mass of the particle
B. Size of the particle
C. Material of the particle
D. Shape of the particle
12
432Which of the following particles neutron, proton,electron and deuteron has the lowest energy if all have the same de Broglie wavelength:
A. neutron
B. proton
c. electron
D. deuteron
12
433Two large vertical and parallel metal
plates having a separation of ( 1 mathrm{cm} ) are
connected to a ( D C ) voltage source of
potential difference ( X . ) A proton is released at rest midway between the
two plates. It is found to move at ( 45^{circ} ) to
the vertical JUST after release. Then ( boldsymbol{X} )
is nearly
A. ( 1 times 10^{-5} V )
В . ( 1 times 10^{-7} V )
c. ( 1 times 10^{-9} V )
D. ( 1 times 10^{-10} V )
12
434The de-Broglie wavelength of an electron traveling with speed equal to ( 1 % ) of the speed of light:
( A cdot 400 mathrm{pm} )
в. 120 pm
( c .242 mathrm{pm} )
D. 375 pm
12
435Write Einstein’s photo electric equation.12
436If kinetic energy of an electron is
reduced by ( (1 / 9) ) then how many times its de Broglie wavelength will increase?
A . 3
B. 4
c. 5
D. 6
12
437Light of two different frequencies whose
protons have energies ( 1 e V ) and ( 2.5 e V )
respectively, successively illuminate a metallic surface whose work function is
( 0.5 e V . ) Ratio of maximum speeds of
emitted electrons will be
A .1: 5
B. 1: 4
c. 1: 2
D. 1: 1
12
438( x- ) rays of wavelength ( lambda ) falls on a
photosensitive surface emitting electrons.Assuming that the work
function of the surface can be
neglected, prove that the de Broglie wavelength of electrons emitted will be ( sqrt{frac{h lambda}{2 m c}} )
12
439Name the unit in which work function of
a metal is generally expressed. How is it related to the S.I. unit joule?
( mathbf{A} cdot e V, 1 e V=1.6 times 10^{9} J )
B . ( e V, 1 e V=1.6 times 10^{-9} J )
c. ( e V, 1 e V=1.6 times 10^{-19} J )
D. ( e V, 1 e V=1.6 times 10^{19} J )
12
440A photon of frequency n causes photoelectric emission from a surface
with threshold frequency ( v_{o} ). the de
Broglie wavelength ( lambda ) of the photoelectron emitted is given as:
A ( cdot Delta n=frac{h}{2 m lambda} )
B. ( Delta n=frac{h}{lambda} )
( ^{mathrm{C}}left[frac{1}{v_{o}}-frac{1}{v}right]=frac{m c^{2}}{h} )
D. ( lambda=sqrt{frac{h}{2 m Delta n}} )
12
441A charged dust particle of radius ( 5 times ) ( 10^{-7} mathrm{m} ) is located in a horizontal
electric field having an intensity of ( 6.28 times 10^{5} v / m . ) The surrounding
medium is air with coefficient of
viscosity ( boldsymbol{eta}=mathbf{1 . 6} times mathbf{1 0}^{-mathbf{5}} mathbf{N S} / mathbf{m}^{2} . ) If the
particle has a charge of ( 7.2 times 10^{-15} )
then it moves with a uniform horizontal
speed of
A . 10
в. 20
( c .30 )
D. 40
12
whose photon energies are ( 3.4 e V ) and ( 8.2 e V ) successive illuminate a metal
surface whose work function is ( 1.8 e V )
The ratio of the maximum speeds of the
emitted electrons will be:
A . 1: 1
B. 1: 2
( c cdot 1: 3 )
D. 1: 4
12
443A particle is dropped from a height ‘ ( boldsymbol{H} ) ‘.
The de Broglie wavelength of the particle depends on height as
A. ( H )
B. ( H^{-1 / 2} )
( mathrm{c} cdot H^{0} )
D. ( H^{1 / 2} )
12
444OUPS
51. When a certain metallic surface is illuminated with
monochromatic light of wavelength 2, the stopping
potential for photoelectric current is 3V, and when the
same surface is illuminated with light of wavelength 22,
the stopping potential is V. The threshold wavelength of
this surface for photoelectric effect is
(a) 62
(b) 41/3
(c) 42
(d) 82
12
445If velocity of a particle is 3 times of that of electron and ratio of de brogile wavelength of particle to that of
electron is ( 1.814 times 10^{-4} . ) The particle
will be:-
A. Neutron
B. Deutron
c. Alpha
D. Tritium
12
446Find the de Broglie wavelength of
electrons moving with a speed of ( 7 times ) ( 10^{6} m s^{-1} )
12
447Find the de-Broglie wavelength of an electron with kinetic energy of ( 120 e V )
( mathbf{A} cdot 95 p m )
в. ( 102 mathrm{pm} )
c. 112 pm
D. ( 124 mathrm{pm} )
12
448Which of the following expression gives the de-Broglie relationship?
A ( cdot p=frac{h}{m v} )
B. ( lambda=frac{h}{m v} )
c. ( lambda=frac{h}{m p} )
D ( cdot lambda m=frac{v}{p} )
12
449An ( alpha ) particle moves in circular path of
radius ( 0.83 mathrm{cm} . ) In the presence of a
magnetic field of ( 0.25 W b / m^{2} . ) Find the De Broglie wavelength associated with the particle
12
450Let ( p ) and ( E ) denote the linear
momentum and the energy of a photon. For another photon of smaller wavelength (in same medium)
A. Both ( p ) and ( E ) increase
B. ( p ) increases and ( E ) decreases
c. ( p ) decreases and ( E ) increases
D. Both ( p ) and ( E ) decrease
12
451Light of wavelength ( 5000 dot{A} ) and intensity ( 3.96 times 10^{-3} W / c m^{2} ) is
incident on the surface of a
photosensitive material. If 1 percent of incident photons only emit
photoelectrons, then the number of electrons emitted per unit area from the surface will be
A ( cdot 10^{16} )
B. ( 10^{18} )
( c cdot 10^{20} )
D. ( 10^{2} )
12

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