Electromagnetic Waves Questions

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

Electromagnetic Waves Questions

List of electromagnetic waves Questions

Question NoQuestionsClass
1A. Current flow inside the capacitor due to accumulation of charges on the capacitor walls is called displacement
current.
B. Current due to the flow of electrons
due to some potential difference is called as conduction current.
C. Displacement current came into existence when Maxwell observed that
if a magnetic compass is placed between the capacitors the needle gets deflected which signifies presence of magnetic fields which would possibly caused due to some changing current.
D. Displacement current change the actual motion of electric charges. Which of the above statement(s) is/are
correct?
A. A and B only
B. A, B and C only
c. ( c ) only
D. ( A, B, C ) and ( D )
12
29. The energy of X-rays photon is 3.3 x 10 ° J. Its frequency is
(a) 2 x 10’Hz (b) 5 x 108 Hz
(c) 5 x 1017 Hz (d) 5 x 1016 Hz
12
3The pressure exerted by an electromagnetic wave of intensity
( Ileft(w a t t / m^{2}right) ) on a non-
reflecting surface is : ( [mathrm{c} ) is the velocity of light
( mathbf{A} cdot I c )
B . ( I c^{2} )
( c cdot I / c )
D. ( I / c^{2} )
12
4associated with electromagnetic radiations in different contexts in
physics. State the part of the electromagnetic spectrum to which
each belongs.
(a) ( 21 mathrm{cm} ) (wavelength emitted by atomic hydrogen in interstellar space).
(b) 1057 MHz (frequency of radiation
arising from two close energy levels in hydrogen; known as Lamb shift).
(c) ( 2.7 mathrm{K} ) [temperature associated with the isotropic radiation filling all space thought to be a relic of the big-bang origin of the universe].
( (d) 5890 A-5896 dot{A}[ ) double lines of
sodium]
(e) 14.4 ke ( V ) [energy of a particular transition in ( ^{57} ) Fe nucleus associated
with a famous high resolution spectroscopic method Mössbauer spectroscopy)].
12
5A parallel plate capacitor of plate
separation 2 mm is connected in an electric circuit having source voltage ( 400 V . ) What is the value of the
displacement current for ( 10^{-6} ) second if
the plate area is ( 60 mathrm{cm}^{2} . ? )
12
6Which of the following type of radiations are radiated by on oscillating electric charge?
A. Electric
B. Magnetic
c. Thermoelectric
D. Electromagnetic
12
7Which one of following have highest frequency?
A . radio waves.
B. infrared.
c. ultraviolet.
D. gamma rays
12
8Fluorescent tubes give more light than a filament bulb of same power because
A. the tube contains gas at low temperature
B. ultraviolet light is converted into visible light by fluorescence
c. light is diffused through the walls of the tube
D. it produces more heat than bulb
12
93. The dimensions of 1/Močo, where symbols have their usual
meanings, are
(a) [
LT]
(b) [L-2 T21
(c) [L?T?1
(d) [LT’) (AIEEE 2003)
12
10ILLUSTRATION 25.4 Suppose that the electric field amplitude
of an electromagnetic wave is Eo = 120 N/C and that its
frequency is v = 50.0 MHz. (a) Determine Bo, 0, k, and 2
(b) Find expressions for Ē and B.
Solution
12
11A plane electromagnetic wave is incident on a material surface. If the
wave delivers momentum ( p ) and energy
( boldsymbol{E}, ) then:
A ( , p=0, E=0 )
0
В. ( p neq 0, E neq 0 )
c. ( p neq 0, E=0 )
D. ( p=0, E neq 0 )
12
12In an electromagnetic wave
A. Power is equally transferred along the electric and magnetic fields
B. Power is transmitted in a direction perpendicular to both the fields
C. Power is transmitted along electric field
D. Power is transmitted along magnetic field
12
13Give the uses of ultraviolet radiation12
14The spectrum of molecular form the substance is called:
A. band spectrum
B. line spectrum
c. absorption spectrum
D. continuous spectrum
12
15Assertion
Electromagnetic waves carry energy
and momentum.
Reason
Electromagnetic waves can be
polarised.
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
16The Sun delivers ( 10^{3} W / m^{2} ) of electromagnetic flux to the Earth’s
surface. The radiation force on the
roof of dimensions ( 8 m times 20 m ) will be:
A ( cdot 3.33 times 10^{-5} N )
В. ( 5.33 times 10^{-4} N )
( mathbf{c} cdot 7.33 times 10^{-3} N )
D. ( 9.33 times 10^{-2} N )
12
17Which of the following effects could not be explained by Maxwell’s electromagnetic wave theory?
A. Photoelectric effect
B. Compton effect
c. Raman effect
D. All of these
12
18A wave has a wavelength of ( 0.01 A^{circ} ) Name the wave:
A. ( x ) rays
B. Micro waves
c. Gamma waves
D. Radio waves
12
19Assertion
A charge moving in a circular orbit can
produce electromagnetic wave.
Reason
The source of electromagnetic wave
should be in accelerated motion.
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
20Two monochromatic (wavelength ( =boldsymbol{a} / mathbf{5} )
and coherent source of
electromagnetic waves are placed on the ( x ) -axis at the point ( (2 a, 0) ) and
( (-a, 0) . ) A detector moves in a circle of radius ( R(>>2 a) ) whose Centre is at
the origin. The number of maximas detected during one circular revolution by the detector are:
A . 60
в. 15
c. 64
D. None
12
21The waves that are propagated by simultaneous periodic variations of electric and magnetic field intensity known as:
A. Transverse wave
B. Longitudinal wave
c. Electromagnetic wave
D. None of the above
12
22Electromagnetic wave of intensity ( 1400 W / m^{2} ) falls on metal surface on
area ( 1.5 m^{2} ) is completely absorbed by
it. Find out force exerted by beam.
A ( cdot 14 times 10^{-5} N )
В. ( 14 times 10^{-6} N )
( mathbf{c} cdot 7 times 10^{-5} N )
D. ( 7 times 10^{-6} N )
12
23To distinguish between real gems and artificial gems a merchant may use which of the following radiations?
A. Infrared rays
B. ( gamma ) -rays
c. x-rays
D. Ultraviolet rays
12
24A wave has wavelength ( 50 A^{circ} . ) State the
speed of wave in vacuum.
A. ( 3 times 10^{8} mathrm{ms}^{-1} )
В ( ldots 3 times 10^{8} m s^{-1} )
( mathbf{c} cdotleftlangle 3 times 10^{8} m s^{-1}right. )
D. Insufficient information
12
25When light propagates in vacuum there is an electric field and a magnetic field. These fields
This question has multiple correct options
A. are constant in time
B. have zero average value
c. are perpendicular to the direction of propagation of light
D. are mutually perpendicular
12
26Light with an energy flux of ( 18 W / c m^{2} ) falls on a non-reflecting surface at normal incidence. The pressure exerted on the surface is:
A. ( 2 N / m^{2} )
B . ( 2 times 10^{-4} N / m^{2} )
c. ( 6 N / m^{2} )
D. ( 6 times 10^{-4} N / m^{2} )
12
27State whether given statement is True or False
MRI uses radio-waves.
A. True
B. False
12
28As speed decreases, if we change medium of electromagnetic waves from air to water, frequency
A . also decreases
B. also increases.
c. remains same.
D. may increase or decrease
12
29In a cylindrical space uniform electric field varies with respect to time with rate ( (d E / d t) . P ) is a point at a distance
( r ) from the axis of the space. Deduce the
expression for the magnetic field at ( P )
12
30The matter-wave picture of electromagnetic wave/radiation elegantly incorporated the:
A. Heinsenbergs uncertainty principle
B. correspondence principle
c. cosmic theory
D. Hertzs observations
12
31The electromagnetic waves do not
transport
A. energy
B. charge
c. momentum
D. information
12
32The electric field of an electromagnetic wave traveling through the vacuum is given by the equation ( boldsymbol{E}= )
( boldsymbol{E}_{0} sin (boldsymbol{K} boldsymbol{x}-boldsymbol{omega} boldsymbol{t}) . ) The quantity that is
independent of wavelength is:
A . ( k omega )
в. ( frac{k}{omega} )
( mathbf{c} cdot k^{2} omega )
( D )
12
33Radiation 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
34Maxwell introduced displacement current to remove the conceptual contradiction in
A. Gauss’s law in electrostatics
B. Gauss’s law in magnetism
c. Faraday’s law
D. Ampere’s law
12
35Microwaves are detected by
A. barometer
B. point contact diodes
C. thermopiles
D. the eye
12
36The ionospheric layer acts as a reflector for the frequency range
( mathbf{A} cdot 1 mathrm{kHz} ) to ( 10 mathrm{kHz} )
B. 3 to 30 МНz
( c cdot 3 ) to ( 30 mathrm{kHz} )
D. 100 kHz to 1 MHz
( E . ) 3 GHz to 30 GHz
12
37e
W NV V
12. An electromagnetic wave going through vacuum is
described by E = E, sin(kx – Ot); B = Bo sin(kx – 00)
Which of the following equation is true
(a) Eok = Bo
(b) E,o= Bok
(c) EB. = ok
(d) None of these
12
38What do you mean by electromagnetic
waves? Write the names of all
electromagnetic waves from gamma rays to radio waves in order of their increasing wavelengths.
12
39Earth’s atmosphere is transparent for
A. only the visible light
B. only the X-rays
c. only the ( gamma ) – rays
D. visible light and microwaves
12
40In which of the following media can nonmechanical waves travel?
B. In vacuum but not in a medium
c. In a medium but not in a vacuum
D. Neither in a medium nor in vacuum
12
41Name an electromagnetic wave which
is used in the radar system used in aircraft navigation. Give another use of
the wave.
12
42According to Maxwell’s hypothesis, a changing electric
field gives rise to
(a) an e.m.f.
(b) electric current
(c) magnetic field (d) pressure radiant
12
43Most energetic radiations and fluorescence are properties of
A. Gamma rays
B. UV Rays
c. Infrared Rays
D. Radio waves
12
44A ( 1000 Omega ) resistance and a capacitor of
100 ( Omega ) resistance are connected in
series a ( 220 V ) source. when the
capacitor is ( 50 % ) charged, the value of the displacement current is.
A ( .11 . sqrt{2} A )
в. ( 2.2 A )
( c .11 A )
D. ( 4.4 A )
12
45Fill in the blanks with suitable words
The range of wavelength of visible light is
12
46The magnetic field in a plane electromagnetic wave is given by ( = ) ( 2 times 10^{-7} sin left(0.5 times 10^{3} x+1.5 times 10^{11} tright) )
This electromagnetic wave is
A. Visible light
B. Infrared
c. Microwave
D. Radiowave
12
47Which of the following is correct for ( X ) rays?
A. It has a beam of electrons
B. It is electromagnetic waves
c. It is positively charged particle
D. It is negatively charged particles
12
4812. An observer is moving with half the speed of light
towards a stationary microwave source emitting waves
at frequency 10 GHz. What is the frequency of the
microwave measured by the observer? (Speed of light
= 3 x 10 ms)
(a) 17.3 GHz
(b) 15.3 GHz
(c) 10.1 GHz
(d) 12.1 GHz
(JEE Main 2017)
12
49An accelerated electron would produce
A . ( gamma ) -rays
B. ( beta ) -rays
c. ( alpha ) -rays
D. electromagnetic rays
12
50An electron gun with its collector at a
potential of ( 100 V ) fires out electrons in
a spherical bulb containing hydrogen gas at low pressure ( left(sim 10^{-2} m m text { of } mathrm{Hg}right) )
A magnetic field of ( 2.83 times 10^{4} T ) curves
the path of the electrons in a circular
orbit of radius ( 12.0 mathrm{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
5115. If c is the speed of electromagnetic waves in vacuum te
speed in a medium of dielectric constant K and relativ
permeability u, is
(a) v=-
(b) v=cu,K
VUK
K
(C) v= TMK
(d) v=
Suc
12
52The rms value of the electric field of the
light coming from sun is ( 720 mathrm{N} C^{-1} ). The
average total energy density of the electromagnetic wave is
в. ( 4.5810^{-6} mathrm{Jm}^{-3} )
c. ( 6.3710^{-9} mathrm{Jm}^{-3} )
D. ( 81.3510^{-12} mathrm{Jm}^{-3} )
12
5327. The wave of wavelength 5900 Å emitted by any atom
or molecule must have some finite total length which is
known as coherence length. For sodium light, this length
is 2.4 cm. The number of oscillations in this length will be
(a) 4.068 x 108 (b) 4.068 x 104
(c) 4.068 x 10
(d) 4.068 x 10%
12
54White light is passed through a dilute solution of potassium permagnate. The spectrum produced by the emergent light is
A. Band emission spectrum
B. Line emission spectrum
c. Band absorption spectrum
D. Line absorption spectrum
12
55Assertion
Radio waves are diffracted by buildings.
Reason
Radio waves are high energy waves.
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
56Draw the diagram of electromagnetic
wave
12
5733. In a region of free space the electric field at some instant of
time is E = (801+32) – 64k) V/m and the magnetic field
is B = (0,21 +0,08% -0.296)ut. The pointing vector for
these fields is
(a) -11.52 + 28.8; (b) -28.81 +11.521
(c) 28.82 -11.52] (d) 11.521 – 28.89
12
5810. During the propagation of electromagnetic waves in a
medium:
(a) Electric energy density is equal to the magnetic energy
density.
(b) Both electric and magnetic energy densities are zero.
(c) Electric energy density is double of the magnetic
energy density.
(d) Electric energy density is half of the magnetic energy
density.
(JEE Main 2014)
12
59Which of the following is not the
characteristics of electromagnetic
wave?
A ( . ) The electric and magnetic fields ( vec{E} ) and ( vec{B} ) are always perpendicular to the direction in which the wave is travelling
B. The electric field is always perpendicular to the magnetic field
C. The cross product ( vec{E} times vec{B} ) always gives the direction in which the wave travels
D. The fields do not vary simultaneously
12
60ILLUSTRATION 25.2 A plane electromagnetic wave travels in
vacuum along z-direction. What can you say about the
directions of its electric and magnetic field vectors? If the
frequency of the wave is 30 MHz, what is its wavelength?
12
616. The rms value of the electric field of the light coming from
sun is 720 N/C. The average energy density of the emf is
(a) 3.3 x 10-J/m’ (b) 4.58 x 10-J/m3
(c) 6.37 x 10-‘J/m3 (d) 81.35 x 10-12 J/m3
(AIEEE 2006)
12
62To which part of the electromagnetic
spectrum does a wave of frequency ( 3 x )
( 10^{13} H z ) belong?
12
63For transmission of speeches, talks, music, dramas etc is used
A. radio broadcast transmittter
B. radio telegraph transmitter
c. navigation transmitter
D. None of these
12
64Two waves ( A ) and ( B ) have wavelength
( 0.01 A^{circ} ) and ( 9000 A^{circ} ) respectively. Compare the speeds of these waves
when they travel in vacuum.
A . 1: 9
B. 9: 1
c. 1: 1
D. None of the above
12
65Assertion
Microwaves are better carrier of signals
than the optical waves.
Reason
Microwaves move faster than optical
waves.
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
6613. An EM wave from air enters a medium. The electric fields are
En = Epicos 2.00 — ) in air
Em = Eo2 cos[k(2z – ct)] in medium,
where the wave number k and frequency v refer to their
values in air. The medium is non-magnetic, if Eri and 8,2
refer to relative permittivities of air and medium respec-
tively, which of the following options is correct?
(a) E11
(b)
&
2
مه ته كه اته
E = 2
12
67An electromagnetic wave passing
through vacuum is described by the
equations. ( boldsymbol{E}=boldsymbol{E}_{0} sin (boldsymbol{k} boldsymbol{x}-boldsymbol{omega} boldsymbol{t}) ) and
( B=B_{0} sin (k x-omega t) . ) Then
A ( cdot E_{0} k=B_{0} omega )
в. ( E_{0} omega=B_{0} k )
c. ( E_{0} B_{0}=omega k )
D. ( E_{0}=B_{0} )
12
68A capacitor has been charged by a DC
source. What are the magnitude of conduction and displacement current, when it is fully charged?
12
69Draw and label the diagram showing various regions of Electro-magnetic spectrum and their wavelength ranges.12
70Assertion: Dipole oscillations produce electromagentic waves, Reason: Accelerated charge produces electromagnetic waves
A. If both assertion and reason are true but the reason is the correct explanation of assertion.
B. If both assertion and reason are true but the reason is not the correct explanation of assertion.
c. If assertion is true but reason is false
D. If both the assertion and reason are false
E. If reason is true but assertion is false
12
71Which of the following has the shortest
wavelength?
A. Red light
B. Blue light
c. Gamma rays
D. x rays
E. Radio waves
12
72u
5. The wave associated with 2.7 K belongs to
(a) radio waves
(b) micro waves
(c) ultraviolet ways (d) infrared waves
12
73Write the approximate wavelengths for red light.
A ( cdot 1000 A^{circ} )
( ^{circ} )
B. 2000A”
c. ( 4000 A^{circ} )
D. ( 8000 A^{circ} )
12
74Choose the correct answer from
alternatives given. If ( vec{E} ) and ( vec{B} ) represent electric and magnetic field vectors of an electromagnetic wave, the direction of propagation of the wave is along
( mathbf{A} cdot vec{B} times vec{E} )
в. ( vec{B} )
( c cdot vec{E} )
D. ( vec{E} times vec{B} )
12
75The subjective property of light related to its wavelength is ………. (colour, refractive index).12
76Analyse the diagram of solar spectrum and write answer.
a. Which radiation has a wavelength greater than visible light in this
spectrum?
b. Which color has the highest
frequency in the visible part of the solar spectrum?
c. Write one merit and demerit of
infrared and ultraviolet radiations.
12
77Assume you are sitting in sun for 2.5 hours. The area of your body exposed normally to sun rays ( 1.3 m^{2} . ) The
intensity of sun rays is 1.1 Kilowatt ( / m^{2} )
If your body completely absorbs the sun rays then the momentum transferred to your body will be (in ( mathrm{Kg}-mathrm{m} / mathrm{s} ) ):
( mathbf{A} cdot 0.043 )
B. 0.037
c. 0.61
D. -0.91
12
78ILLUSTRATION 25.6 About 5% of the power of a 100 W light
bulb is converted to visible radiation. What is the average
intensity of visible radiation
(a) At a distance of 1 m from the bulb?
(b) At a distance of 10 m?
Assume that the radiation is emitted isotropicailly and ne-
glect reflection.
12
79An electromagnetic wave has a frequency of ( 500 M H z ) and a wavelength of ( 60 mathrm{cm} ). Name the medium
through which it is traveling.
A . air
B. water
c. salt
D. cardboard
12
80The wavelength range of thermal
radiation is
A. from ( 4000 AA ) to 7000 ,
B. from 7700 A to ( 4 times 10^{6} ) A
c. from ( 10^{6} AA ) to ( 10^{8} AA )
D. from ( 4 times 10^{-12} AA ) to ( 4 times 10^{8} AA )
12
81Why are microwaves used in radars?12
82What name is given to the type of astronomy having the following characteristics.
I. It is carried out in the waveband 300
nm to 10 nm.
II. The atmosphere is opaque to the incoming radiation from space
III. Observations are to be carried out
from above the earth’s atmosphere.
A. X-ray astronomy
B. Ultra-violet astronomy
c. Infra-red astronomy
D. Gamma ray astronomy
12
83Give two uses of Infrared Rays.12
84What is displacement current? Why was this concept introduced? Explain.
Also obtain the
Ampere-Maxwell equation.
12
85Instantaneous displacement current
( 1 A ) in the space between the parallel
plates of ( 1 mu F ) capacitor can be
established by changing the potential difference at the rate of:
A ( .0 .1 V / s )
B. ( 1 V / s )
c. ( 10^{6} V / s )
D. ( 10^{-6} V / s )
12
868. X-rays are not used for radar purposes, because they are not
(a) reflected by target
(b) partly absorbed by target
(c) electromagnetic waves
(d) completely absorbed by target
CYLLA hote22 10-16 C
12
87Select wrong statement from the following:
Electromagnetic waves
A. are transverse
B. travel with same speed in all media
c. travel with the speed of light
D. are produced by accelerating charge
12
88Name the region beyond the red end of
the spectrum.
A. Ultra red
B. infra red
c. dark red
D. light red
12
89If ( lambda_{v}, lambda_{x}, lambda_{m} ) represents the wavelengths of vision, X-ray and microwaves
respectively then
A ( cdot lambda_{m}>lambda_{x}>lambda_{v} )
в. ( lambda_{m}>lambda_{v}>lambda_{x} )
c. ( lambda_{v}>lambda_{x}>lambda_{m} )
D ( cdot lambda_{v}>lambda_{m}>lambda_{x} )
12
90If the frequencies of an ultrasonic wave and an electromagnetic wave are same,
then:
A. their wavelength will be same
B. wavelength of electromagnetic wave will be less than that of ultrasonic wave
c. wavelength of electromagnetic wave will be more than that of ultrasonic wave
D. the wavelengths of both will be nearly equal
12
91A parallel plate capacitor consists of two circular plates each of radius ( 12 mathrm{cm} )
and separated by ( 5.0 m m . ) The capacitor
is being charged by an external source. The charging current is constant and is
equal to ( 0.15 A )
The displacement current is:
( mathbf{A} cdot 15 A )
в. ( 1.5 A )
c. ( 0.15 A )
D. ( 0.015 A )
12
92We consider the radiation emitted by the human body. Which of the following statements is true:
A. The radiation emitted is in the infrared region
B. The radiation is emitted only during the day
c. The radiation is emitted during the summers and absorbed during the winters
D. The radiation emitted lies in the ultraviolet region and hence is not visible
12
93Which of the following is not an electromagnetic wave?
A. Radio waves
B. X-rays
c. Earthquake P-waves
D. Gamma rays
12
9428. A radiowave has a maximum electric field intensity of
10 *V m’on arrival at a receiving antenna. The maximum
magnetic flux density of such a wave is
(a) zero
(b) 3 x 104 T
(c) 5.8 x 10-9 T (d) 3.3 x 10-13 T
12
95Choose the correct answer from the
alternatives given. Which of the following is not true for
electromagnetic waves?
A. They transport energy.
B. They have momentum.
C. They travel at different speeds in air depending on their frequency.
D. They travel at different speeds in medium depending on their frequency.
12
96A parallel plate capacitor (fig.) made of circular plates each of radius ( boldsymbol{R}= )
( 6.0 mathrm{cm} ) has a capacitance ( C=100 mu mathrm{F} )
The capacitor is connected to a ( 230 V )
ac supply with a (angular) frequency of 300 rad ( s^{-1} . ) Determine the amplitude of
( B ) at a point ( 3.0 mathrm{cm} ) from the axis
between the plates.?
12
97A plane electromagnetic wave propagating along ( x ) direction can have the following pairs of ( vec{E} ) and ( vec{B} ).
A. ( E_{y}, B_{z} )
в. ( E_{z}, B_{y} )
c. ( E_{x}, B_{y} )
D. both (a) and (b)
12
98Light is an electromagnetic wave. Its speed in vacuum is given by the expression
в. ( sqrt{frac{mu_{0}}{varepsilon_{0}}} )
c. ( sqrt{frac{varepsilon_{0}}{mu_{0}}} )
D. ( frac{1}{sqrt{mu_{0} varepsilon_{0}}} )
12
99The waves relevant to
telecommunications are
A. visible light
B. infrared
c. ultraviolet
D. microwave
12
100If phase Difference between ( mathrm{E} ) and 1 is ( frac{pi}{4} ) and ( f=50 mathrm{Hz} ) then calculate time
difference.
12
101A. wavelength of microwave is greater than that of ultraviolet rays.
B. The wave length of infrared rays is lesser than that of ultraviolet rays.
C. wavelength of microwave is lesser than that of ultraviolet rays
D. Gamma rays has shortest wavelength in the electromagnetic spectrum. Choose the correct option from the
given options.
( A ). A and ( B ) are true
B. B and C are true
c. ( c ) and ( D ) are true
D. A and D are true
12
102Name the region beyond the violet end,
of the spectrum
A. infraviolet
B. ultraviolet
c. darkviolet
D. lightviolet
12
103A plane electromagnetic wave of frequency 20 MHz travels through a space along ( x ) direction. If the electric field vector at a certain point in space is
( 6 mathrm{V} boldsymbol{m}^{-1}, ) what is the magnetic field
vector at that point?
A ( cdot 2 times 10^{-8} T )
B ( cdot frac{1}{2} times 10^{-8} T )
c. ( 2 T )
D. ( frac{1}{2} T )
12
104Fill in the blanks with suitable words
The rays used to show bone structure is
12
105Which of the following has/have zero average value in a plane electromagnetic wave?
A. Both magnetic and electric field
B. Electric field only
c. Magnetic energy
D. Electric energy
12
106Speed of electromagnetic waves is the
same:
A. for all wavelengths
B. in all media
c. for all intensities
D. for all frequencies
12
107Define displacement current.12
108Which of the following conclusion can be drawn from the result ( oint bar{B} cdot d bar{A}=0 )
A. Magnetic field is zero everywhere
B. Magnetic monopole cannot exist
c. Magnetic lines of force do not intersect each other
D. A current produces magnetic field
12
109Why welders generally wear mask during welding?12
110If a source is transmitting an electromagnetic wave of frequency ( 8.2 times 10^{6} H z, ) then the wavelength of
the electromagnetic waves transmitted from the source will be:
A . ( 36.6 m )
в. ( 40.5 mathrm{m} )
c. 42.3 m
D. ( 50.9 m )
12
111Displacement current goes through the gap between the plates of a capaitor when the charge of the capacitor:
(i) does not change
(ii) change with time
(iii) increases
(iv) decreases
( A cdot(i),(text { iii }) ) and ( (text { iv }) )
B. (i), and (ii) and (iv)
c. ( ii ), (iii) and (iv)
D. (i), (ii) and (iii)
12
112What is displacement current? Obtain
an expression of displacement current for a charged capacitor. Write AmpereMaxwell’s law.
12
113The electromagnetic waves of frequency
range 100 to ( 300 G H z ) are used in
12
1146. The percentage power of X-ray increases with the
increases in its
(a) velocity
(b) intensity
(c) frequency
(d) wavelength
12
115A collimated beam of light of flux
density ( 3 k W m^{-2} ) is incident normally
on a ( 100 m m^{2} ) completely absorbing screen. If ( P ) is the pressure exerted on the screen and ( Delta p ) is the momentum transferred to the screen during a 1000 s interval, then
This question has multiple correct options
A. ( P=10^{-3} N m^{-2} )
В. ( P=10^{-4} N m^{-2} )
c. ( Delta p=10^{-4} )Kgms( ^{-} )
D. ( Delta p=10^{-5} mathrm{Kgms}^{-1} )
12
116The AM range of radiowaves has frequency:
A. less than 30 MHz
B. more than 30 Мн н
c. less than 20000 Hz
D. more than 20000Hz
12
117Unpolarized light falls first on polarizer
( (P) ) and then on analyzer ( (A) . ) If the
intensity of the transmitted light from the analyser is ( frac{1}{8} ) th of the incident unpolarized light. What will be the angle between optic axes of ( boldsymbol{P} ) and ( boldsymbol{A} ) ?
A ( cdot 45^{circ} )
B. ( 30^{circ} )
c. zero
D. ( 60^{circ} )
12
118PAR range of wavelength is
A. ( 400-700 n m )
в. ( 400-800 n m )
c. ( 450-950 n m )
D. ( 500-600 n m )
12
119List the properties of electromagnetic
waves.
12
120What is the range of wavelength of the spectrum of white light in ( boldsymbol{A}^{o} ) ?
A ( .4000 A^{circ} ) to ( 5000 A^{circ} )
B. ( 5000 A^{circ} ) to ( 6000 A^{circ} )
c. ( 6000 A^{circ} ) to ( 8000 A^{circ} )
D. All the above
12
121The smoke from a fire looks white.
Which of the following statements is
true?
1. Molecules of the smoke are bigger than the wavelength of light.
2. Molecules of the smoke are smaller
than the wavelength of light.
12
122Which of the following doesnt represent
Maxwells equation?
( mathbf{A} cdot oint vec{E} cdot d vec{A}=frac{q}{varepsilon_{0}} )
B ( cdot oint vec{B} cdot d vec{A}=0 )
c. ( oint vec{E} cdot bar{d} l=frac{-d B}{d t} )
D ( cdot oint vec{B} cdot bar{d} l=mu_{0} I_{C}+mu_{0} varepsilon_{0} frac{d phi_{E}}{d t} )
12
12314. If yo be the permeability and K, the dielectric constant of
a medium, its refractive index is given by
(b)
SMOKO
Moko
(d) MOKO
12
124Fill in the blanks.
Current flowing through the resistor is known as while the
current flowing through the capacitor is
commonly known as
A. eddy current, displacement current
B. displacement current, conduction current
c. conduction current, eddy current
D. conduction current, displacement current
12
125According to the electromagnetic spectrum. Which of the following is NOT a pure spectral colour?
A. white
B. violet
( c cdot ) red
D. blue
E. yellow
12
126Which of the following is not true for electromagnetic waves?
A. They transport energy.
B. They have momentum.
C. They travel at different speeds in air depending on their frequency.
D. They travel at different speeds in medium depending on their frequency.
12
127When light propagates in vaccum there is an electric field and a magnetic field.
Which of the following is not true about these field?
A. They are constant in time
B. They have zero average value
C. They are perpendicular to the direction of propagation of light
D. They are mutually perpendicular
12
128A parallel plate capacitor (fig.) made of circular plates each of radius ( boldsymbol{R}= ) ( 6.0 mathrm{cm} ) has a capacitance ( C=100 mu mathrm{F} )
The capacitor is connected to a ( 230 V ) ac supply with a (angular) frequency of
300 rad ( s^{-1} )
Is the conduction current equal to the
displacement current?
12
129If ( epsilon_{0} ) and ( mu_{0} ) represent the permittivity and permeability of vaccum and ( epsilon ) and ( mu ) represent the permittivity and permeability of medium, then refractive index of the medium is given by
A. ( sqrt{frac{epsilon_{0} mu_{0}}{epsilon mu}} )
в. ( sqrt{frac{epsilon mu}{epsilon_{0} mu_{0}}} )
c. ( sqrt{frac{epsilon_{0} mu_{0}}{epsilon}} )
D. ( sqrt{frac{epsilon_{0} mu_{0}}{mu}} )
12
130Which one of the following is a property of a monochromatic, plane
electromagnetic wave in free space?
A. Electric and magnetic fields have a phase difference of ( pi / 2 )
B. The energy contribution of both electric and magnetic fields are equal
c. The direction of propagation is in the direction of ( bar{B} ) x ( bar{E} )
D. The pressure exerted by the wave is the product of its speed and energy density
12
131Choose the correct answer from the
alternatives given

A parallel plate capacitor with plate
area ( A ) and separation between the
plates ( d ) is charged by a constant current ( I . ) Consider a plane surface of area ( frac{boldsymbol{A}}{mathbf{2}} ) parallel to the plate and drawn between the plates. The displacement current through the area is :
( A )
в. ( frac{I}{2} )
c. ( frac{I}{4} )
D. ( frac{I}{8} )

12
132According to the electromagnetic wave theory, light consists of electric and
magnetic fields which are
A. parallel to each other
B. perpendicular to each other
C . inclined at an angle of ( 45^{circ} ) to each other
D. none of these
12
133Who predicted the existence of electromagnetic waves? Give the wavelength range of electromagnetic
spectrum.
12
134Психос
с топливного пола.
3. In an electromagnetic wave, the electric and magnetising
fields are 100 Vm-and 0.265 Am !. The maximum energy
flow is
(a) 26.5 W/m²
(b) 36.5 W/m2
(C) 46.7 W/m2
(d) 765 W/m²
12
13531. A plane em wave of wave intensity of 10 W/m² strikes
a small mirror of area 20 cm“, held perpendicular to the
approaching wave. The radiation force on the mirror will be
(a) 6.6 x 10- N (b) 1.33 X 10-11 N
(C) 1.33 x 10-10 N (d) 6.6 x 10-10 N
12
136Assertion
Electromagnetic radiations exert
pressure.
Reason
Electromagnetic-waves carry both momentum and energy.
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
137Write the name of any four waves (radiations) produced in electromagnetic spectrum.12
1381. Electromagnetic waves are transverse in nature as is
evident by
(a) polarisation
(b) interference
(c) reflection 3 (d) diffraction
(AIEEE 2002)
12
139On changing of medium, remains same.
A. Wavelength
B. Frequecy
c. speed
D. None
12
140In the propagation of light waves, the angle between the plane of vibration ( & ) plane of polarisation is:
A ( cdot 0^{circ} )
B. ( 90^{circ} )
c. ( 45^{circ} )
D. ( 80^{circ} )
12
141In electromagnetic wave, according to Maxwell, changing electric field gives
A. stationary magnetic field
B. conduction current
c. eddy current
D. displacement current
12
142In which colour an yellow coloured dress
would appear when viewed through a blue filter?
A . yellow
B. blue
c. black
D. green
12
14319. The average energy-density of electromagnetic wave given
by E = (50 N/C) sin(@t – kx) will be nearly
(a) 10-8 J/m3 (b) 10-7J/m3
(c) 10- J/m3 LED (d) 10-5 J/m3
12
144For an electromagnetic radiation,
A. only momentum is quantised
B. only energy is quantised
C. both energy and momentum are quantised
D. neither of them is quantised
12
145colo
lu) 4 00
24. The sun delivers 10 W/m² of electromagnetic flux to the
earth’s surface. The total power that is incident on a roof
of dimensions 8 m x 20 m will be
(a) 2.56 x 104 W ) (b) 6.4 x 10% W
(c) 4.0 x 10 W (d) 1.6 10 W
12
146Considering the case of a parallel plate capacitor being charged, show how one is required to generalize Ampere’s circuital law to include the term due to
displacement current.
12
147In which one of the following regions of the electromagnetic specturm will the vibration motion of molecules give rise
to absorption?
A . Ultraviolet
B. Microwave
c. Infrared
D. Radio wave
12
148The increasing order of frequencies for infrared rays, Ultraviolet rays-, X-rays and Y-rays will be-
A. y-rays, X-rays, Infrared rays, Ulterviolet rays
B. X-rays,Y-rays Infrared rays,Ultraviolet rays
C. Infrared rays, Ultraviolet rays,X-rays, Y-rays
D. Ultraviolet rays,X-rays, Y-rays Infrared rays
12
149Explain the inconsistency of Ampere’s circuital law during charging of a capacitor. Define displacement current12
150A long spring is fixed at one end. ( A )
person holding the other end compresses the spring with a jerk. The compression travels along the length of the spring. Which kind of wave is
travelled along the length of the spring?
A. Electromagnetic waves
B. Transverse waves
c. Longitudinal waves
D. Both (A) and (C)
12
151In an electromagnetic wave, the electric magnetising fields are ( 100 V / m ) and
0.265 A. The maximum energy flow is?
( mathbf{A} cdot 26.5 W / m^{2} )
B. ( 36.5 W / m^{2} )
( mathbf{c} cdot 46.7 W / m^{2} )
( mathbf{D} cdot 765 W / m^{2} )
12
152Which one of waves cannot be seen
through electromagnetic spectrum?
A. radio waves
B. micro waves
c. infrared waves.
D. ultraviolet waves
12
153Find the mismatch
A. Sky wave communication: Frequency upto 30 MHz
B. Line-of-sight communication: Frequency greater than ( 40 mathrm{MHz} )
C. Mobile telephony : Frequency range ( 800-950 mathrm{kHz} )
D. Facsimile : Static document
E. Ground wave propagation: Frequency less than a few МНz
12
154A parallel plate capacitor with plate area A and separation between the
plates ( d, ) is charged by a constant
current ( i . ) Consider a plane surface of area ( frac{boldsymbol{A}}{mathbf{2}} ) parallel to the plate and down symmetrically between the plates. Find the displacement current through this
area.
A ( cdot i_{d}=frac{i}{8} )
B. ( i_{d}=frac{i}{2} )
( mathbf{c} cdot_{i_{d}=frac{i}{3}} )
D ( i_{d}=frac{i}{4} )
12
155Infrared radiations are used in
A. Microwave ovens
B. Long distance photography
c. Microscopes
D. Treatment of cancer
12
156What is the speed of Light ( c ) ?
A ( cdot c=3 times 10^{-8} mathrm{ms}^{-1} )
B . ( c=3 times 10^{8} k m s^{-1} )
c. ( c=3 times 10^{8} mathrm{mms}^{-1} )
D. ( c=3 times 10^{8} mathrm{ms}^{-1} )
12
157International broadcasting requires.
A. Medium frequency radio waves
B. High frequency radio waves
c. Low frequency radio waves
D. Longitudinal waves
12
158Electromagnetic waves are:
A. Transverse
B. Longitudinal
C. May be longitudinal or transverse
D. Neither longitudinal nor transverse
12
159A parallel beam of light is incident normally on a plane surface absorbing ( 40 % ) of the light and reflecting the rest. If the incident beam carries 60 watt of
power, the force exerted by it on the surface is:
A . ( 3.2 times 10^{-8} N )
В. ( 3.2 times 10^{-7} N )
c. ( 5.2 times 10^{-7} N )
D. ( 5.12 times 10^{-8} N )
12
160Write any three uses of infrared
radiations.
12
161¡) ff force( = )mass( times )acceleration
then momentum ( = )
ii) If liquid hydrogen is for rocket, then is for MRI
12
162Write any two Maxwell’s equation.12
163When an object absorb waves and energy their temperature increases.
A. True
B. False
12
164Choose the correct answer from the
alternatives given

Maxwell in his famouse questions
of eletromagnetism introduce the
concept of:
A . ac current
B. displacement current
c. impedance
D. reatance

12
165Which of the following represents an infra-red wavelength?
A ( cdot 10^{-4} mathrm{cm} )
B. ( 10^{-5} mathrm{cm} )
( mathrm{c} cdot 10^{-6} mathrm{cm} )
D. ( 10^{-7} mathrm{cm} )
12
166A radiation ( A ) is focused by a proper
device on the bulb of a thermometer.
Mercury in the thermometer shows a
rapid increase. The radiation ( boldsymbol{A} ) is:
A . infrared radiation
B. visible light
c. ultraviolet radiation
D. X-rays
12
167Match the EM waves from list I with
corresponding Inventors in list II:
12
168toppr
Q Type your question
magnet, carrying magnetic effect, electricity, the magnitude of current deflection increases, eastwards,
southwards.
Oersted was the first to put forth the direct relation between ( _{text {thend }} ) and
magnetism. He conducted several experiments to determine the of a current wire
The following describes the Oersted experiment conducted to establish that
a current carrying wire acts as a

A long straight wire is connected to an external battery and an electric current is passed through it. When a magnetic needle is placed below the wire such
that the wire is parallel to the axis of the
magnetic needle and the current flows in the south to north direction, a
deflection in the needle is observed. It is
observed that the north pole of the needle is deflected westwards and as
the ( _{text {一一一一一一一 }} ) is increased, the
deflection, ( _{text {一一一一一一一 }} ) till the north pole
of the needle turns towards exact west.
t is also observed that if instead of
placing the magnetic needle below the wire, if it was placed above the wire, the
north pole of the magnetic needle is deflected

12
169Choose the correct answer from the
alternatives given. Which among the following does not represent Maxwell’s equation?
A ( cdot phi bar{E} cdot d A=frac{q}{varepsilon_{0}} )
B ( cdot phi bar{B} cdot overline{d A}=0 )
c. ( phi bar{E} .-overline{d l}=frac{-d B}{d t} )
D. ( phi bar{E} cdot overline{d l}=mu_{0} I_{C}+mu_{0} varepsilon_{0} frac{d phi E}{d t} )
12
17016. In a plane electromagnetic wave, the electric field
oscillates sinusoidally at a frequency of 2.5 x 100 Hz
and amplitude 480 V/m. The amplitude of the oscillating
magnetic field will be
(a) 1.52 x 10-8 Wb/m2 (b) 1.52 x 10-7Wb/m²
(c) 1.6 x 10-Wb/m2 (d) 1.6 x 10-7Wb/m2
12
171Light of intensity ( =3 W / m^{2} ) is incident
on a perfectly absorbing metal surface of area ( 1 m^{2} ) making an angle of ( 60^{circ} ) with the normal. If the force exerted by
the photons on the surface is ( boldsymbol{p} times 10^{-9} )
(in Newton), then the value of p is :
A. 5
B. 2
( c )
( D .3 )
12
17213. A radio receiver antenna that is 2 m long is oriented als
the direction of the electromagnetic wave and recei
a signal of intensity 5 x 10-0 W/m”. The maxi
instantaneous potential difference across the two ends of
the antenna is
(a) 1.23 uV
(b) 1.23 mV
(c) 1.23 V
(d) 12.3 m V
12
173What are electromagnetic waves? Write
its nature.
12
174In the spectrum of visible light produced by a prism, dispersion is
A. Uniform throughout the spectrum
B. Maximum in the middle, decreases on either sides
c. Maximum towards yellow
D. Maximum towards violet
12
175Write the name of electromagnetic wave produced by vacuum tube
magnetron.
12
176Who first proposed the light as electromagnetic wave?
A. Thomas Young
B. Max planck
c. James Clerk Maxwell
D. Albert Einstein
12
177Astronauts communicate with one
another on moon with the help of
A. radio waves
B. sound waves
c. ultrasound waves
D. infrasound waves
12
178An electromagnetic wave of frequency
( boldsymbol{v}=mathbf{3} ) MHz passes from a vacuum into
a dielectric medium with permittivity
( =4, ) Then
A. Wavelength and frequency both become half.
B. Wavelength is doubled and frequency remains unchanged.
C. Wavelength and frequency both remains unchanged.
D. Wavelength is halfved and frequency remains unchanged.
12
179Fill in the blanks with suitable words:
Electromagnetic waves are
waves
12
1805. An electromagnetic wave of v = 3 MHz passes from
vacuum into dielectric medium with ε = 4.0 Then
(a) the wavelength is doubled and the frequency becomes
half.
(b) the wavelength is doubled and the frequency remains
same.
(c) the wavelength and frequency both remain unchanged.
(d) the wavelength is halved but the frequency remains
same.
(AIEEE 2004)
12
181EM waves are
A. deflected by electric and magnetic waves
B. not deflected by electric and magnetic waves
C. sometimes deflected sometimes not deflected
D. none of the above
12
182The electromagnetic waves travel in free space with the velocity of
A. Sound
B. Light
c. Greater than that of light
D. Greater than that of sound
12
18325. In Q. 24, the radiation force on the roof will be
(a) 8.53 × 10-N (b) 2.3 x 10-‘N
(c) 1.33 x 10-‘N (d) 5.33 x 10-4 N
12
184The wavelength of light visible to eye is of the order of
( mathbf{A} cdot 10^{-4} m )
B. ( 10^{-8} mathrm{m} )
( mathbf{c} cdot 10^{-10} m )
D. ( 10^{-7} m )
12
1857. An electromagnetic wave in vacuum has the electric and
magnetic field E and B , which are always perpendicular
to each other. The direction of polarization is given by X
and that of wave propagation by k. Then
(a) X || B and k || B E
(b) X || E and k || E B
(c) X || B and k’ || E x B
(d) X || E and k || B
(AIEEE 2012)
X
X
X
12
1864. The 21 cm radio wave emitted by hydrogen in interstellar
space is due to the interaction called the hyperfine
interaction is atomic hydrogen. the energy of the emitted
wave is nearly
(a) 10–joule
(b) 1 joule
(c) 7× 10-ºjoule (d) 10-24 joule
12
187In a parallel C-R network with a voltage
source, the current flowing through
resistor is
flowing through the capacitor is
current.
A. conduction, displacement
B. displacement, conduction
C. displacement, displacement
D. conduction, conduction
12
1882. Which of the following has zero average value in a plane
electromagnetic wave?
(a) Electric field (b) Magnetic potential
(c) Electric energy (d) Magnetic energy
12
189A parallel plate capacitor is charged to ( 60 mu C . ) Due to a radioactive source, the
plate loses charge at the rate of ( 1.8 times ) ( 10^{-8} C / s . ) The magnitude of
displacement current is:
A . ( 1.8 times 10^{-8} mathrm{C} / mathrm{s} )
B. ( 3.6 times 10^{-8} mathrm{C} / mathrm{s} )
c. ( 4.1 times 10^{-11} mathrm{C} / mathrm{s} )
D. ( 5.7 times 10^{-12} mathrm{C} / mathrm{s} )
12
190The working of a microwave oven
involves
A. Absorption of microwaves by matter
B. Reception of microwaves by optical fibre
C. Microwave amplification by stimulated emission of radiation
D. Transmission of microwaves through a metal
12
191The charge on a parallel plate capacitor
is varying as ( boldsymbol{q}=boldsymbol{q}_{0} sin (2 pi n t) . ) The
plates are very large and close together. neglecting the edge effects, the displacement current through the capacitor is:
( ^{text {A. }} frac{q}{varepsilon_{0}} )
в. ( frac{q_{0}}{varepsilon_{0}} sin 2 pi n t )
( mathbf{c} cdot 2 pi n q_{0} cos 2 pi n t )
( stackrel{mathrm{D}}{cdot} frac{2 pi n q_{0}}{varepsilon_{0}} cos 2 pi n t )
12
192Write the approximate wavelengths for blue light?
( mathbf{A} cdot 800 A^{circ} )
B . ( 1600 A^{circ} )
c. ( 3200 A^{circ} )
D. ( 4800 A^{circ} )
12
1938. The magnetic field in a travelling electromagnetic wave
has a peak value of 20 nt. The peak value of electric field
strength is
(a) 6 V/m
(b) 9 V/m
(c) 12 V/m
(d) 3 V/m (JEE Main 2013)
12
194(i) What is main difference between
electromagnetic waves theory and Planck’s quantum theory.
(ii) Which rule is violated in the
following orbital diagram:
12
195Write an expression for the displacement current12
196On the basis of the following features identify correct option:
I. They require no material medium.
II. They are always transverse.
I. They are produced by accelerating charged particles
A. Mechanical waves
B. Electro-magnetic waves
c. Both (1) and (2)
D. Neither (1) and (2)
12
197Electromagnetic waves travel only
through.
( mathbf{A} ). material medium
B. vacuum
C. oscillating electric and magnetic fields
D. oscillating electric and magnetic fields whose directions are perpendicular to each other
12
198Which part of electromagnetic
spectrum has largest penetrating
power?
12
199Which of the following sources of light is different from others
A. Sunlight
B. White light
c. Light from a bulb
D. sodium light
12
200The ( r m s ) value of conduction current
will be:
( mathbf{A} cdot 5.7 mu A )
в. ( 6.3 mu A )
( mathrm{c} .9 .6 mu A )
D. ( 6.9 mu A )
12
201Which one of waves tans our skin and
causes some substances to become
fluorescent?
A. infrared waves
B. ultraviolet waves
c. gamma rays
D. infrared and ultraviolet waves both
12
202Assertion
When variable frequency a.c. source is connected to a capacitor, displacement current increases with increase in
frequency
Reason
As frequency increases conduction current also increases.
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
203Which of the following is not one of the prime health risks associated with
greater UV radiation due to the
depletion of stratospheric ozone?
A. Increased liver cancer
B. Increased skin cancer
c. Reduced immune systemmm
D. Damage to eyes
12
204Where are radiowaves used?
A. Radar, radio and tv communications
B. Microwave ovens
C. Photographic films
D. sterilizing purpose
12
205Electromagnetic waves are transverse in nature is evident by
A. polarization
B. interference
c. reflection
D. diffraction
12
206The waves used by artificial satellites for communication is the
A. microwaves
B. infrared waves
c. radio waves
D. x-rays
12
207Which scientist experimentally proved the existence of electromagnetic wave.
A. Marconi
B. Hertz
c. мaxwell
D. S.C.Bose
12
208What is the range of wavelength of the spectrum of white light in ( n m ? )
A. ( 400 n m ) to ( 500 n m )
B. ( 500 n m ) to ( 600 n m )
c. ( 600 n m ) to 800 nm
D. All the above
12
209UUT Piucu unu ul WC Salle
le.
6. In which one of the following regions of the electromagnetic
spectrum will the vibrational motion of molecules give
rise to absorption
(a) ultraviolet
(b) microwaves
(c) infrared
(d) radio waves
orion lin in the
12
210In which form does the Light
propagates?
A. Electric waves
B. Magnetic waves
c. Electromagnetic waves
D. sound wave
12
211Identify which of the following is NOT a characteristic of electromagnetic
waves?
A. contain electrical properties
B. have crests and troughs
c. contain magnetic properties
D. travel through space
E. have crests but no troughs
12
212Read the following statements.
a. Ozone in found mostly in the
stratosphere
b. Ozone layer lies ( 55-75 ) kms above the surface of the earth.
c. 0 zone absorbs ultraviolet radiation
from the Sun
d. Ozone layer has no significance for life on the earth.
Which set of the statements is correct?
A. a and c
B. b and d
( c . ) b and ( c )
D. a and d
12
213A long straight cable of lenght ( l ) is
placed symmetrically along z – axis has radius ( a(<<l) ). The cable consists of a
thin wire and a coaxial conducting tube
An alternating current ( boldsymbol{I}(boldsymbol{t})= )
( I_{0} sin (2 pi v t) ) flows down the central thin
wire and return along the coaxial conducting tube. The induced electric field at a distance s from the wire inside
the cable is ( boldsymbol{E}(boldsymbol{s}, boldsymbol{t})= )
( mu_{o} I_{o} v cos (2 pi v t) ln left(frac{s}{a}right) hat{k} . ) The
displacement current density inside the cable is
A ( cdot frac{2 pi}{lambda^{2}} I_{0} ln left(frac{a}{s}right) sin (2 pi v t) hat{k} )
в. ( frac{I}{lambda^{2}} I_{0} ) ln ( left(frac{a}{s}right) sin (2 pi v t) hat{k} )
c. ( frac{pi}{lambda^{2}} I_{0} ln left(frac{a}{s}right) sin (2 pi v t) hat{k} )
D. Zero
12
21418. A flood light is covered with a fitter that transmits red light.
The electric field of the emerging beam is represented by
a sinusoidal plane wave
E, = 36 sin (1.20 x 10′ 2-3.6 x 10’st) V/m
The average intensity of beam in W/m² will be
(a) 6.88
(b) 3.44
(c) 1.72
(d) 0.86
12
215The most energetic electromagnetic radiations are:
A. microwaves
B. ultraviolet waves
c. ( X ) -rays
D. gamma rays
12
2165. The oscillating electric and magnetic vectors of an
electromagnetic wave are oriented along
(a) The same direction but differ in phase by 90°
(b) The same direction and are in phase
(c) Mutually perpendicular directions and are in phase
(d) Mutually perpendicular directions and differ in phase
by 90°
12
217Which of the following ray is not electromagnetic wave?
A. X-rays
B. ( gamma ) -rays
c. ( beta ) -rays
D. Heat rays
12
218According to Maxwell’s equation, the velocity of light in any medium is expressed as
A ( cdot frac{1}{sqrt{mu_{0} varepsilon_{o}}} )
в. ( frac{1}{sqrt{mu varepsilon}} )
c. ( sqrt{frac{mu}{varepsilon}} )
D. ( sqrt{frac{mu_{0}}{varepsilon}} )
12
21922. The sum delivers 104 W/m² of electromagnetic flux to the
earth’s surface. The total power that is incident on a roof
of dimensions (10 x 10) m” will be
(a) 104 w
(b) 10 W
(c) 10° w
(d) 10′ W
12
220The frequency of optical waves is of the
order of
12
221The displacement current is
A ( cdot_{varepsilon_{o}} frac{d phi_{E}}{d t} )
в. ( frac{varepsilon_{o}}{R} frac{d phi_{E}}{d t} )
( mathbf{c} cdot_{varepsilon_{o}} frac{E}{R} )
D. ( varepsilon_{o} q frac{C}{R} )
12
222The portion of the spectrum beyond the red end is called
B. Infrard spectrum
c. Microwave
D. All
12
223Which of the following is/are electromagnetic wave(s)?
A. Microwaves
B. Radio wave
c. Infrared radiation
D. All of the above
12
224The oscillating electric and magnetic
vectors of an electromagnetic wave are
oriented along
A. the same direction but differ in phase by ( 90^{circ} )
B. the same direction and are in phase.
C. mutually perpendicular directions and are in phase.
D. mutually perpendicular directions and differ in phase by ( 90^{circ} )
12
225Electromagnetic waves of wavelength ranging from ( 100 dot{A} ) to ( dot{A} ) comes under
A. X-rays
B. UV regions
c. Visible region
D. Infrared region
12
226Which of the following relations is correct for electromagnetic waves:
A ( cdot frac{partial^{2} E}{partial x^{2}}=frac{1}{c^{2}} frac{partial^{2} E}{partial t^{2}} )
( ^{mathrm{B}} frac{partial^{2} E}{partial x^{2}}=left(frac{partial E}{partial t}right)^{2} )
c. ( frac{partial^{2} E}{partial x^{2}}=frac{c^{2} partial^{2} E}{partial t^{2}} )
D. ( frac{partial^{2} E}{partial x^{2}}=c frac{partial^{2} E}{partial t^{2}} )
12
227Which of the following are use of
microwaves?
A. They are used for satellite communication.
B. They are used for analysis of atomic and molecular structure.
C. They are used cooking in microwave ovens.
D. All of the above.
12
228A plane electromagnetic wave of frequency ( 28 M H z ) travels in free space along the positive x-direction. At a particular point in space and time, electric field is ( 9.3 V / m ) along positive y-direction. The magnetic field (in T) at that point is
A ( cdot 3.1 times 10^{-8} ) along positive z-direction
B . 3.1 ( times 10^{-8} ) along negative z-direction
C. ( 3.2 times 10^{7} ) along positive z-direction
D. 3.2 ( times 10^{7} ) along negative z-direction
12
229An electromagnetic wave radiates outwards from a dipole antenna, with
( E_{0} ) as the amplitude of its electric field
vector. The electric field ( E_{0} ) which
transports significant energy from the source falls off as
A ( cdot frac{1}{r^{3}} )
B. ( frac{1}{r^{2}} )
( c cdot frac{1}{r} )
D. remains constant
12
230Write the relation for the speed of
electromagnetic waves in terms of the
amplitudes of electric and magnetic fields.
12
231SQUID helps in studying
A. lung cancer
B. heart beats
C. weaker magnetic waves from brain
D. electrical impulses from heart
12
232An electromagnetic wave radiates outwards from a dipole antenna, with
( E_{0} ) as the amplitude of its electric field
vector. The electric field ( B_{0} ) which
transports significant energy from the source falls off as
A ( cdot frac{1}{r^{3}} )
B. ( frac{1}{r^{2}} )
( c cdot frac{1}{r} )
D. remains constant
12
233How can Infrared radiations be harmful
for humans
A. Can cause blindness
B. Can cause skin burns
c. can cause hairfall
D. can cause frostbite
12
234A parallel plate condenser consists of two circular plates each of radius ( 2 mathrm{cm} ) separated by a distance of 0.1 m
time varying potential difference of ( 5 times ) ( 10^{13} v / s ) is applied across the plates of the condenser. The displacement
current is:
( mathbf{A} cdot 5.50 A )
B . ( 5.56 times 10^{2} A )
c. ( 5.56 times 10^{3} A )
D. ( 2.28 times 10^{4} A )
12
235Is the colour of 620 nm light and 780
nm light same? Is the colour of ( 620 mathrm{nm} )
light and 621 nm light same? How many colours are there in white light?
12
236Plane electromagnetic wave of intensity
S are incident normally on a flat
surface.Only a fraction ( f ) of the incident energy is absorbed.What is the
radiation pressure?
12
23710. In X-ray tube, the accelerating potential applied at the
anode is V volt. The minimum wavelength of the emitted
X-ray will be
(a) eVlh
(b) hleV
(c) eVich
(d) hcleV
12
238Write the mathematical equation of
Ampere-Maxwell law’
12
239In an electromagnetic wave, the direction of the magnetic induction ( vec{B} )
is
A. parallel to the electric field ( vec{E} )
B. perpendicular to the electric field ( vec{E} )
C . antiparallel to the pointing vector ( vec{S} vec{S} )
D. random
12
240ILLUSTRATION 25.1 What physical quantity is the same for
X-rays of wavelength 10-10 m, red light of wavelength
6800 Å, and radiowaves of wavelength 500 m?
1.
1
.
1
.
1:
1
:
1
12
241Which of the following lights has maximum wavelength?
A ( cdot gamma ) – rays
B. X – rays
c. UV – rays
D. Visible rays
12
242Radio waves with frequencies higher than television signals are
A. ultrasonic waves
B. sound waves
c. light waves
D. microwaves
12
243The visible part of electromagnetic
spectrum lies in between
A. ( x ) -ray and ultra-violet
B. Ultra violet and infra red
C. Infra red and microwave
D. X-ray and infra red
12
244Which of the following are not electromagnetic waves?
A. cosmic rays
B. gamma rays
c. ( beta ) -rays
D. x-rays
12
245Radio isotope useful in treating blood
cancer is
A. Cobalt 40
B. Carbon 60
c. cobalt 60
D. Carbon 14
12
246Which of the following colors of light has the lowest frequency?
A. Yellow
B. Violet
c. orange
D. Blue
E. Green
12
247Maxwell in his famous equations of electromagnetism, introduced the
concept of
A . ac current
B. displacement current
c. impedance
D. reactance
12
248(a) 5.6 x 106
(c) 4.2 x 106
The intensity of sunlight (in W/m) at the solar surface will be
(b) 5.6 x 107
(d) 4.2 x 107
12
249If ( c ) is the speed, ( nu ) is frequency and ( lambda ) is wavelength of EM waves, then
A ( . c=nu lambda )
B. ( frac{lambda}{nu}=c )
c. ( frac{nu}{lambda}=c )
D. ( frac{1}{lambda}=frac{c}{nu} )
12
250Infrared radiation was discovered in
1800 by :
A. William Wallaston
B. William Herschel
c. wilhelm Roentgen
D. Thomas Young
12
251In photocell cesium, coated oxidized silver cathode emits electrons for
A. visible light.
B. ultraviolet
c. infrared light
D. x-rays
12
2527. The shortest wavelength of X-rays remitted from an X-ray
tube depends upon
(a) nature of the gas in the tube
(b) voltage applied to the tube
(c) current in the tube
(d) nature of target of the tube
12
253The Electromagnetic wave travelling in a medium has relative permeability 1.3 and relative premittivity 2.14. The speed
of EM wave in that medium will be.
( mathbf{A} cdot 13.6 times 10^{6} mathrm{m} / mathrm{s} )
B . ( 1.8 times 10^{6} mathrm{m} / mathrm{s} )
c. ( 3.6 times 10^{8} mathrm{m} / mathrm{s} )
D. ( 1.8 times 10^{8} mathrm{m} / mathrm{s} )
12
254A piece of blue glass heated to a high temperature and a piece of red glass at room temperature are taken inside a
dimly-lit room. Then
A. The blue piece will look blue and the red piece will look red as usual
B. The red piece will look brighter red and the blue piece will look ordinary blue
c. The blue will look brighter as compared to the red piece
D. Both the pieces will look equal red
12
255Radiations of intensity ( 0.5 mathrm{W} / mathrm{m} 2 ) are striking a metal plate. The pressure on the plate is
A ( cdot 0.166 times 10^{-8} N / m 2 )
В. ( 0.332 times 10-8 N / m^{2} )
c. ( 0.111 times 10-8 N / m^{2} )
D. ( 0.083 times 10-8 N / m^{2} )
12
256Identify which of the following light rays has the highest energy?
A . Violet
B. Green
c. Yellow
D. orange
E. Red
12
2571. In an apparatus, the electric field was found to oscillate
with an amplitude of 18 V/m. The magnitude of the
oscillating magnetic field will be
(a) 4 x 10-6T
(b) 6 x 10-T
(c) 9 x 10-‘T
(d) 11 x 10-11T
12
258Cavitation is a special application property exhibited only by:
A. Ultrasonics
B. Electromagnetic waves
c. Audible sound
D. Infrasonics
12
259The transverse nature of
electromagnetic radiation is
demonstrated by.
A. Interference experiment
B. Diffraction experiment
c. Polarisation experiment
D. optical activity experiment
12
260Which of the following electromagnetic waves is used in medicine to destroy
cancer cells?
A . IR-rays
B. Visible rays
c. Gamma rays
D. Ultraviolet rays
12
261State Maxwell’s theory of
electromagnetic wave related to light Write down four characteristics of
electromagnetic waves.
12
262Which of the following is not an electromagnetic wave?
A. Light rays
B. X-rays
c. Alpha rays
D. Gamma rays
12
263Photons of an electromagneitc
radiation has an energy ( 11 k e V ) each. To which region of electromagnetic spectrum does it belong?
A. ( X- )ray region
в. Ultra violet region
c. infrared region
D. visible region
12
264Maxwell’s four equations are written as
(i) ( oint overrightarrow{boldsymbol{E}} cdot overrightarrow{boldsymbol{d}} boldsymbol{s}=frac{boldsymbol{q}_{0}}{varepsilon_{0}} )
(ii) ( oint vec{B} cdot vec{d} s=0 )
(iii) ( oint overrightarrow{boldsymbol{E}} cdot overrightarrow{boldsymbol{d}} boldsymbol{l}=frac{boldsymbol{d}}{boldsymbol{d} boldsymbol{t}} quad boldsymbol{oint} overrightarrow{boldsymbol{B}} cdot overrightarrow{boldsymbol{d}} boldsymbol{s} )
( (text { iv }) oint vec{B} cdot vec{d} s=mu_{0} varepsilon_{0} frac{d}{d t} oint vec{E} cdot vec{d} s )
Which of the above Maxwell’s equations
shows that electric field lines do not
form closed loops?
A. (i) only
B. (ii) only
c. (iii) only
D. (iv) only
12
265Name the high energetic invisible electromagnetic wave which helps in the study of structure of crystals.
A. ( X ) -rays
B. Cathod rays
c. Gamma rays
D. All of the above
12
266Maxwell’s four equations are written as
(i) ( oint overrightarrow{boldsymbol{E}} cdot overrightarrow{boldsymbol{d}} boldsymbol{s}=frac{boldsymbol{q}_{0}}{varepsilon_{0}} )
(ii) ( oint vec{B} cdot vec{d} s=0 )
(iii) ( oint vec{E} . overrightarrow{d l}=frac{d}{d t} oint vec{B} cdot vec{d} s )
( (text { iv }) oint vec{B} cdot vec{d} s=mu_{0} varepsilon_{0} frac{d}{d t} oint vec{E} cdot vec{d} s )
Out of the four Maxwell’s equation above, which one shows the non-
existence of monopoles?
( A cdot ) (i) and (iv)
B. (ii) only
c. (iii) only
D. none of these
12
267Identify which of the following wave has the longest frequency?
A. Red light
B. Blue light
c. Gamma rays
D. x rays
E. Radio waves
12
268Consider the radiations emitted by the human body. Which of the following statements is true?
A. radiations lie in ultraviolet region
B. radiations lie in infrared region
c. radiations are emitted only during the day
D. radiations are emitted during summer and absorbed during winter
12
269Name the rays or waves of highest frequency.
A. X-rays
B. UV rays
c. IR rays
D. Gamma rays
12
270A type of electromagnetic wave has
wavelength ( 50 A )
What is the speed of the wave in
vacuum?
12
271Which of the following has zero average value in a plane electromagnetic wave?
A. Kinetic energy
B. Magnetic field
c. Electric field
D. Both (b) and (c)
12
272A type of electromagnetic wave has
wavelength ( 50 A )
(i) Name the wave.
(ii) What is the speed of the wave in
vacuum ?
(iii) State one use of this type of wave.
12
273The frequencies of X-rays, ( gamma ) -rays and ultraviolet rays are respectively a, b and
c. Then
( mathbf{A} cdot ac )
В ( . a>b, b>c )
c. ( a>b, b<c )
D. ( a<b, b<c )
12
274In Maxwell’s velocity distribution curve
area under the graph
A. Increases when temperature is increased
B. Deccreases when temperature is increased
C. Remains same at all temperature
D. Depends on the pressure of the gas
12
275Which of the following radiations has the least wavelength?
A. ( gamma ) -rays
B. ( beta ) -rays
c. ( alpha ) -rays
D. X-rays
12
276( mathbf{A} )
( 1.5 k W ) (kilo-watt) laser beam of wavelength ( 6400 dot{A} ) is used to levitate a
thin aluminium disc of same area as
the cross section of the beam. The laser
light is reflected by the aluminium disk without any absorption. The mass of the
disc is close to:
A ( cdot 10^{-9} k g )
в. ( 10^{-3} mathrm{kg} )
( mathrm{c} cdot 10^{-4} mathrm{kg} )
D. ( 10^{-6} mathrm{kg} )
12
277EM waves are
A. Longitudinal waves
B. Transverse waves
c. Both
D. None
12
278According to Maxwell’s equation, the velocity of light in any medium is expressed as
( ^{mathbf{A}} cdot frac{1}{sqrt{mu_{0} varepsilon_{0}}} )
в. ( frac{c}{sqrt{mu varepsilon}} )
c. ( frac{mu}{sqrt{varepsilon}} )
D. ( sqrt{frac{mu_{0}}{varepsilon}} )
12
27935. In an electromagnetic wave, the electric field oscillated
sinusoidally with amplitude 45 Vm, the rms value of
oscillating magnetic field will be
(a) 1.6 x 10-8T (b) 16 x 10-91
(c) 144 x 10-T (d) 11.3 x 10-8T
12
280Choose the correct answer from the
alternatives given. Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor
A . increases
B. decreases
c. increases or decreases
D. is zero
12
281Assertion
The electromagnetic wave is transverse
in nature.
Reason
Electromagnetic wave propagates
parallel to the direction of electric and
magnetic fields.
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
2825. A laser beam of pulse power 1012 watt is focussed on an
object are 104 cm². The energy flux in watt/cm² at the
point of focus is
(a) 1020
(c) 108
(b) 1016
(d) 104
12
283What are electromagnetic waves?
Describe Maxwell’s electromagnetic theory in brief.
12
284A parallel plate capacitor (fig.) made of circular plates each of radius ( boldsymbol{R}= ) ( 6.0 mathrm{cm} ) has a capacitance ( C=100 mu mathrm{F} )
The capacitor is connected to a ( 230 V ) ac supply with a (angular) frequency of 300 rad ( s^{-1} . ) What is the ( r m s ) value of
the conduction current?
12
285Arrange the following electromagnetic waves in increasing order of their frequencies (i.e., begin with the lowest frequency): Visible light, ( gamma ) rays, X rays
micro waves, radio waves, infrared radiations and ultraviolet radiations.
12
286Mention two applications of infrared
radiation.
12
287The range of wavelength of visible light is:
A ( .10 AA ) to ( 100 AA )
в. 4000 月 to 7000 音
c. ( 8000 dot{A} ) to ( 10,000 dot{A} )
D. ( 10,000 dot{A} ) to ( 15,000 dot{A} )
12
28813. A plane electromagnetic wave
E, = 100 cos(6 x 10°t + 4x) V/m
propagates in a medium of dielectric constant
(a) 1.5
(b) 2.0
(c) 2.4
(d) 4.0
12
289Fill the most suitable option. Mosquitoes and some snakes find their food using vision in the ( _{—} ) range
A. infrared
B. ultraviolet
c. radio
D. microwave
E. visible light
12
290Which of the following light has the combination of all frequencies of visible light?
A. white light
B. black light
C. ultraviolet light
D. infrared light
E. transparency
12
291The concept of displacement current
introduced by Maxwell removes
asymmetry between
A. Gauss’s law in electrostatics and Gauss’s law in magnetism
B. Faraday’s law and Ampere’ law
C. Gauss’s law and Ampere’s law
D. Gauss’s law and Faraday’s law
12
292Do electromagnetic waves carry energy
and momentum?
12
293Which of the following has/have zero average value in a plane electromagnetic wave?
A. Both magnetic and electric fields
B. Electric fields only
c. Magnetic field only
D. None of these
12
294Identify the most notable difference between a ultraviolet wave and a light wave?
A. Speed
B. Refractive index
c. Reflectivity
D. Amplitude
E. Frequency
12
295In electromagnetic wave, according to Maxwell, changing electric field gives.
A. Stationary magnetic field
B. conduction current
c. Eddy current
D. Displacement current
12
296Name the rays or waves of wavelength
nearly ( 0.1 n m )
A . IR rays
B. UV rays
c. Gamma rays
D. x-rays
12
297High energetic radiations among the following:
A ( . lambda=0.01 A )
B . ( lambda=0.10 A )
c. ( lambda=1.00 A )
( mathbf{D} cdot lambda=40.0 A )
12
298A wave travels out in all directions from
a point source. Justify the expression ( boldsymbol{y}=left(boldsymbol{a}_{0} / boldsymbol{r}right) sin boldsymbol{k}(boldsymbol{r}-boldsymbol{v} boldsymbol{t}), ) at a distance
from the source. Find the speed,
periodicity and intensity of the wave.
12
299Displacement current is continuous:
A. when electric field is changing in the circuit
B. when magnetic field is changing in the circuit
C. in both types of fields
D. through wires and resistance only
12
300It is possible to take pictures of those objects which are not fully visible to the eye using camera films sensitive to
A. ultraviolet rays
B. infrared rays
c. microwaves
D. radiowaves
12
301The amplitude of the magnetic field of a harmonic electromagnetic wave in
vacuum is ( B_{0}=510 ) nT. The amplitude of
the electric field part of the wave is
( mathbf{A} cdot 120 mathrm{N} C^{-1} )
B . ( 163 mathrm{N} C^{-1} )
c. ( 510 mathrm{N} C^{-1} )
D. 153 N ( C^{-1} )
12
302The diagram shows the principal
regions of the electromagnetic
spectrum, with some details labelled.
The diagram is not to scale. What is a typical order of magnitude of the wavelength of the radiation in
region Q?
( A cdot 10^{-7} m )
B. ( 10^{-5} ) m
( c cdot 10^{-2} m )
( D cdot 10^{0} m )
12
303The ultra-high frequency band of radio waves in electromagnetic wave is used
as in:
A. television waves
B. cellular phone communication
c. commercial FM radio
D. both (a) and (c)
12
304Find the
(a) maximum frequency
(b) Minimum wavelength of X-rays produced by ( 30 mathrm{kV} ) electrons.
12
305A type of electromagnetic wave has
wavelength ( 50 A )

State one use of this type of wave.

12
306Solar radiation is
A. Transverse electromagnetic wave
B. Longitudinal electromagnetic wave
C. Stationary wave
D. None of the above
12
307The dimensional formula of wave
number is :
( mathbf{A} cdotleft[M^{0} L^{0} T^{0}right] )
B . ( left[M^{0} L^{-1} T^{0}right] )
C . ( left[M^{0} L^{0} T^{-1}right] )
D. ( left[M^{-1} L^{-1} T^{0}right] )
12
308Which of the following have zero average value in a plane electromagnetic wave?
(i) Magnetic field
(ii) Electric field
(iii) Electric energy
(iv) Magnetic energy.
( A cdot ) (i) and (ii)
B. (i) and (iv)
c. (ii) and (iii)
D. (iii) and (iv)
12
309Which of the following is the infrared wavelength?
A ( cdot 10^{-4} mathrm{cm} )
B ( cdot 10^{-5} mathrm{cm} )
( mathbf{c} cdot 10^{-6} c m )
D. ( 10^{-7} mathrm{cm} )
12
310According to Maxwell’s hypothesis,
changing of electric filed give rise to
A. magnetic field
B. pressure gradient
c. charge
D. voltage
12
311Which of the following electromagnetic wave is used in high precision application like LASIK eye surgery?
A. Microwave
B. Ultraviolet rays
c. Gamma rays
D. X-rays
12
312( boldsymbol{X}- ) ray falling on a material
A. Exerts a force on it
C. Transfers momentum to it
D. Transfers impules to it
12
313A charged particle oscillates about its mean (equilibrium) position with a frequency of ( 10^{9} H z . ) What is the
frequency of the electromagnetic waves produced by the oscillator?
12
314capacitor is being charged by
an
ILLUSTRATION 25.3 The following figure shows capacitor
made of two circular plates. The
capacitor is being charged by an
external source which supply
constant current equal to 0.15 A. Obtain displacement charged
by constant current across plates. Given “ = 1.87×10ºV s.
dt
dv
12
315The incident intensity on a horizontal surface at sea level from the sun is
about ( 1 k W m^{-2} . ) Assuming that 50 per cent of this intensity is reflected and 50 per cent is absorbed, determine the
radiation pressure on this horizontal surface (in pascals).
A ( .8 .2 times 10^{-2} )
В . ( 5 times 10^{-6} )
c. ( 3 times 10^{-5} )
D. ( 6 times 10^{-5} )
12
316According to Maxwell’s hypothesis,
changing of electric field give rise to
A. Magnetic field
B. Pressure gradient
c. charge
D. voltage
12
317Screen S is illuminated by two point
sources ( A ) and ( B ). Another source
C sends a parallel beam of light towards
point ( P ) on the screen. Line ( A P ) is normal
to the screen and the lines ( A P, B P )
and ( mathrm{CP} ) are 6,3 and ( 3 mathrm{m} ) respectively. The
radiant powers of sources A and B are 45 and ( 90 mathrm{W} ) respectively. The beam
from ( C ) is of intensity ( 0.4 ~ W / m^{2} . ) The total incident intensity at ( mathrm{P} ) is
12
318Which one of the following is unstable
A. ( alpha ) ray
в. ( y- ) ray
c. proton
D. neutron
12
319A plane electromagnetic wave of frequency ( 25 ~ M H z ) travels in free
space along the ( x ) -direction. At a particular point in space and time, ( vec{E}=6.3 hat{j} V / m . ) What is ( vec{B} ) at this point?
12
320How are electric vector ( (boldsymbol{E}), ) magnetic vector ( (vec{B}) ) velocity vector
(c) oriented in an electromagnetic wave?
12
32136. The magnetic field in the plane electromagnetic wave is
given by
B = 2 x 10-7 sin(0.5 x 10°x + 1.5 x 10″t) tesla.
The expression for electric field will be
(a) E, = 30/2 sin(0.5×10°x+1.5×101) V/m
(b) E, = 60 sin(0.5 x 10°x + 1.5 x 10”t) V/m
(c) E, = 30/2 sin(0.5×10”x+0.5×10’t) V/m
(d) E, = 60 sin(0.5 x 10°x + 1.5 x 10”t) V/m
12
322A radiation of energy E falls normally on a perfectly reflecting surface. The momentum transferred to the surface
is:
A ( cdot frac{E}{c} )
в. ( frac{2 E}{c} )
c. ( E c )
D. ( frac{E}{c^{2}} )
12
323How are microwaves produced? Why is it necessary in microwave ovens to select the frequency of microwaves to match the resonant frequency of water molecules?12
32423. The average value of electric energy density in an
electromagnetic wave is (E, is peak value)
(6) Eo
260
(c) €,E?
12
325An electron beam passes through a
transverse magnetic field of ( 2 times 10^{-3} )
tesla and electric field ( boldsymbol{E} ) of ( mathbf{3 . 4} times )
( 10^{4} V / m ) acting simultaneously. If the
path of the electrons remain
undeviated, calculate the speed of the electrons
12
326The monoenergetic beams of electronics moving along ( + ) y direction enters a region of uniform electric and magnetic fields. If the beam goes straight through, then in which direction these simultaneously field ( vec{B} ) and ( vec{E} ) are directed?12
327The waves related to tele-
communication are
A. infrared
B. visible light
c. microwaves
D. ultraviolet rays
12
328The sun delivers ( 10^{3} W m^{-2} ) of
electromagnetic flux on the earth’s surface. The total power that is incident
on a roof of dimensions ( 6 m times 30 m ) is
A . ( 1.8 times 10^{5} mathrm{W} )
В. ( 7.2 times 10^{5} mathrm{W} )
( mathbf{c} cdot 0.9 times 10^{5} W )
D. ( 4.5 times 10^{5} mathrm{W} )
12
329A certain color of light towards the purple end of the visible spectrum has a wave length of ( 420 n m ) in vacuum.

What is the frequency of this light? (The speed of light in a vacuum is ( 3.00 times ) ( left.10^{8} m / sright) )
A ( .126 mathrm{Hz} )
B. ( 1.26 times 10^{11} mathrm{Hz} )
c. ( 7.1 times 10^{14} mathrm{Hz} )
D. ( 1.4 times 10^{15} mathrm{Hz} )
E . ( 1.4 times 10^{6} mathrm{Hz} )

12
330Choose the correct answer from the
alternatives given
A plane electromagnetic wave of frequency ( 25 M H z ) travels in free space
along ( X ) -direction. At a particular point in space and time, electric field ( overrightarrow{boldsymbol{E}}= ) ( 6.3 hat{j} V / m . ) What is ( B ) at this point
A ( .1 .2 times 10^{-6} T )
B . ( 1.2 times 10^{-8} T )
c. ( 2.1 times 10^{-6} T )
D. ( 2.1 times 10^{-8} T )
12
33126. A plane electromagnetic wave of wave intensity 6 W/m
strikes a small mirror of area 39 cm², held perpendicular
to the approaching wave. The momentum transferred in
kg ms by the wave to the mirror each second will be
(a) 1.2 x 10-10
(b) 2.4 x 10-9
(c) 3.6 x 10-8
(d) 4.8 x 10-7
12
332Assertion
Ultraviolet radiations of higher
frequency waves are dangerous to human being
Reason
Ultraviolet radiation are absorbed by
the atmosphere
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
333Consider the following processes
(i) Electrical oscillation
(ii) Rapid deceleration of fast electrons
(iii) Atomic transition
Which of these are likely to produce visible light?
A. (iii) only
B. (ii) and (iii)
c. (i) and (iii)
D. (i), (ii) and (iii)
12
334The displacement current flows in the
dielectric of a capacitor when the potential difference across its plates
A. becomes zero
B. has assumed a constant value
c. is increasing with time
D. is decreasing with time
12
335According to Maxwell’s hypothesis, a changing electric field gives rise to
A. an electromagnetic force
B. electric displacement current
c. magnetic field
D. pressure gradient
12
336Identify the constituent radiations of electromagnetic spectrum which
(a) is obsorbed by ozone layer in the atmosphere
(b) i produced by bombarding a metal target by high speed electrons
(c) is used in satellite communication
(d) has wavelength range between 400 nm to ( 700 mathrm{nm} )
12
33734. A plane electromagnetic wave propagating in the
x-direction has wavelength of 60 mm. The electric field
is in the y-direction and its maximum magnitude is
33 V/m-?. The equation for the electric field as function
of x and t is
(a) 11 sin alt – x/c) (b) 33 sin at x 10″(t – xlc)
(c) 33 sin a (t – x/c) (d) 11 sin x 10″(t – x/c)
12
338A beam of electrons accelerated by a large potential difference ( V ) is made to
strike a metal target to produce ( boldsymbol{X} ) rays. For which of the following values of ( V, ) the resulting ( X ) -rays have the
lowest minimum wave length:
A . ( 10 mathrm{KV} )
в. ( 20 mathrm{KV} )
c. ( 30 K V )
D. ( 40 mathrm{KV} )
12
339The wavelengths for the light of red and blue colours are roughly ( 7.8 times 10^{-7} m )
and ( 4.8 times 10^{-7} m ) respectively. Which
colour has the greater speed in glass?
A. Red light
B. Violet light
c. Yellow light
D. All colors have same speed
12
34014. Electromagnetic waves travel in a medium which has
relative permeability 1.3 and relative permittivity 2.14
Then the speed of the electromagnetic wave in the medium
will be
(a) 13.6 x 10° m/s (b) 1.8 x 10 m/s
(c) 3.6 x 108 m/s (d) 1.8 x 108 m/s
12
341The sound waves are the longitudinal
waves. The electromagnetic waves are
12
342A parallel plate capacitor with circular plates of radius ( R ) is being charged as shown. At the instant shown, the
displacement current in the region between the plates enclosed between ( frac{R}{2} ) and ( R ) is given by
A ( cdot frac{3}{4} )
в. ( frac{1}{4} )
( c cdot 3 i )
D. ( frac{4}{3} i )
12
343A pulse of light of duration 100 ns is
absorbed completely by a small object initially at rest. Power of the pulse is
( 30 m W ) and the speed of light ( 3 x )
( 10^{8} m / s . ) The final momentum of the
object is
В . ( 1.0 times 10^{-17} mathrm{kg} mathrm{ms}^{-1} )
c. ( 3 times 10^{-17} k g m s^{-1} )
D. ( 9.0 times 10^{-17} ) в ( g ) ms ( ^{-1} )
12
344Wavelength of gamma rays are:
( mathbf{A} cdot 10^{-10} m ) to less than ( 10^{-14} m )
B. ( 10^{-14} mathrm{m} ) to less than ( 10^{-10} mathrm{m} )
C ( cdot 10^{-11} mathrm{m} ) to less than ( 10^{-14} mathrm{m} )
D. ( 10^{-14} mathrm{m} ) to less than ( 10^{-6} mathrm{m} )
12
345What are the harmful effects of
ultraviolet radiations?
A. It can cause skin cancer
B. It contributes to global warming.
c. It contributes to greenhouse effect.
D. It can cause depletion of natural resources.
12
346In electromagnetic spectrum, the
frequencies of ( gamma ) -rays and ultraviolet
rays are denoted by ( n_{1}, n_{2} ) and ( n_{3} ) respectively then.
A ( cdot n_{1}>n_{2}>n_{3} )
в. ( n_{1}<n_{2}n_{2}<n_{3} )
D. ( n_{1}n_{3} )
12
347The capacity of a parallel plate air capacitor is ( 2 mu F ) and voltage between the plates is changing at the rate of
( 3 V / S . ) The displacement current in the capacitor is:
( mathbf{A} cdot 2 mu F )
в. ( 3 mu F )
c. ( 5 mu F )
D. ( 6 mu F )
12
348Electro magnetic waves are transverse in nature as is evident by
A. polarization
B. interference
c. reflection
D. deffraction
12
349Out of the following, whose velocity is equal to that of light?
A. of ( beta ) rays
B. of sound waves
c. of ultrasonic waves
D. none of these
12
350Magnetic field in a plane electromagnetic wave is given by ( vec{B}=B_{0} sin (k x+omega t) hat{j} T )
Expression for corresponding electric field will be :
Where ( c ) is speed of light.
A ( cdot vec{E}=B_{0} c sin (k x+omega t) hat{k} V / m )
B・ ( vec{E}=frac{B_{0}}{c} sin (k x+omega t) hat{k} V / m )
c. ( vec{E}=-B_{0} operatorname{csin}(k x+omega t) hat{k} V / m )
D . ( vec{E}=B_{0} c sin (k x-omega t) hat{k} V / m )
12
351Displacement current is
A. continuous when electric field is changing in the circuit
B. continuous when magnetic field is changing in the circuit
C . continuous in both types of fields
D. continuous through wires and resistance only
12
352Assertion
Radio waves can be polarised
Reason
Sound waves in air are longitudinal in
nature
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
353The ground state energy of hydrogen atom is ( -13.6 mathrm{eV} ). If an electron makes
a transition from an energy level -1.51 ( mathrm{eV} ) to ( -3.4 mathrm{eV} ), then calculate the wavelength of the spectral line emitted and name the series of hydrogen spectrum to which it belongs.
12
354Identify the waves with the largest
wavelengths.
A. Radio
B. Gamma Rays
c. x-Rays
D. Visible Light
E. Infrared Radiation
12
355Give the range of wavelength of the electromagnetic waves visible to us.
A . ( 1000 A^{circ} ) to ( 4000 A^{circ} )
B . ( 4000 A^{circ} ) to ( 8000 A^{circ} )
c. ( 8000 A^{circ} ) to ( 9000 A^{circ} )
D. ( 400 A^{circ} ) to ( 800 A^{circ} )
12
356Electromagnetic waves that include light belong to
A. light spectrum.
B. electronic spectrum.
c. electromagnet group.
D. electromagnetic spectrum.
12
35711. A red LED emits light at 0.1 watt uniformly around it. The
amplitude of the electric field of the light at a distance of
1 m from the diode is
(a) 1.73 V/m
(b) 2.45 V/m
(c) 5.48 V/m
(d) 7.75 V/m
(JEE Main 2015)
12
358Radiations of intensity ( 0.5 W / m^{2} ) are
striking a metal plate. The pressure on the plate is
A ( cdot 0.166 times 10^{-8} mathrm{N} / mathrm{m}^{2} )
B . ( 0.332 times 10^{-8} mathrm{N} / mathrm{m}^{2} )
c. ( 0.111 times 10^{-8} mathrm{N} / mathrm{m}^{2} )
D. ( 0.083 times 10^{-8} N / m^{2} )
12
3599. The electromagnetic waves do not transport
(a) energy
(b) charge
(c) momentum
(d) information
12
360Name the rays or waves produced by the changes in the nucleus of an atom.
A. X-rays
B. UV rays
c. Gamma rays
D. IR rays
12
361Which waves are used as signal
through fog and why?
12
362Two waves ( A ) and ( B ) have wavelength
( 0.01 A^{circ} ) and ( 9000 A^{circ} ) respectively. Name
the two waves.
A. A-gamma, B-infrared
B. A-gamma, B-ultraviolet
c. A-ultraviolet, B-infrared
D. A-gamma, B-X rays
12
363How electromagnetic waves are produced?12
364Maxwell’s equation describe the fundamental laws of
A. electricity
B. magnetism
c. mechanics
( D . ) both ( (A) ) and ( (B) )
12
365An electromagnetic waves can be produced, when charge is
A. Moving with constant velocity
B. Moving in a circular orbit
c. Falling in an electric field
( D . ) both ( (b) ) and ( (c) )
12
366Name the radiations:
(i) That are used for photography at night.
(ii) Used for detection of fraction in bones.
(iii) Whose wavelength range is from
( 100 A ) to ( 4000 dot{A} ) (or ( 10 n m ) to ( 400 n m ) ).
12
367Mark the correct option in impure
spectrum:
A. order of colours is revers
B. Order of colours is irregular
c. colours are overlapped
D. no colours is present
12

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