Roll No : Name of School : Time - MM- 163
Date : Name of Assessment :
Subject :
Class :
1 Considering the case of a parallel plate capacitor being charged, show how 2
one is required to generalize Ampere’s circuital law to include the term due to
displacement current.
2A capacitor of capacitance C is being charged by connecting it across a dc 2
source along with an ammeter. Will the ammeter show a momentary deflection
during the process of charging? If so, how would you explain this momentary
deflection and the resulting continuity of current in the circuit? Write the
expression for the current inside the capacitor.
3 When an ideal capacitor is charged by a dc battery, no current flows. However, 2
when an ac source is used, the current flows continuously. How does one
explain this, based on the concept of displacement current?
4 (a) How does oscillating charge produce electromagnetic waves? 2
(b) Sketch a schematic diagram depicting oscillating electric and magnetic
fields of an em wave propagating along + z-direction.
5 How are infrared waves produced? Why are these referred to as ‘heat waves’? 2
Write their one important use.
6 Name the electromagnetic radiation having the wavelength range from 1 mm 2
to 700 nm. Give its two important applications.
7 Name the electromagnetic radiation having the wavelength range from 1 nm 2
to 10–3 nm. Give its two important applications.
8(a) An em wave is travelling in a medium with a velocity The electric 2
field oscillations, of this em wave, are along the y-axis. Draw a sketch showing
the propagation of the em wave, indicating the direction of the oscillating
electric and magnetic fields.
(b) How are the magnitudes of the electric and magnetic fields related to the
velocity of the em wave?
9 Experimental observations have shown that X-rays: 2
(a) travel in vacuum with a speed of 3 × 108 ms–1.
(b) exhibit the phenomenon of diffraction and can be polarized.
What conclusion can be drawn about the nature of X-rays from each of then
observations?
10A parallel plate capacitor with plate area A and plate separation d, is charged 2
by a constant current I. Consider a plane surface of area A/2 parallel to the
plates and situated symmetrically between the plates. Determine the
displacement current through this area.
11 (a) The electric field of an electromagnetic wave is represented as Ex = E0 sin 2
(wt + kz).
(i) In which direction is the wave propagating?
(ii) In which direction does the magnetic field oscillate?
(b) Write two characteristics of electromagnetic waves.
12How does Ampere-Maxwell law explain the flow of current through a capacitor 2
when it is being charged by a battery? Write the expression for the
displacement current in terms of the rate of change of electric flux.
13Which of the following electromagnetic waves has (a) minimum wavelength, 2
and (b) minimum frequency? Write one use of each of these two waves.
Infrared waves, Microwaves, g-rays and X-rays
14 How are infrared waves produced? Why are these waves referred to as ‘heat 2
waves’? Give any two uses of infrared waves.
15 (a) Why are infrared waves often called heat waves? Explain. 2
(b) What do you understand by the statement, “Electromagnetic waves
transport momentum”?
16Gamma rays and radio waves travel with the same velocity in free space. 2
Distinguish between them in terms of their origin and the main application.
17 Identify the electromagnetic waves whose wavelengths vary as 2
–12 –8
(a) 10 m < λ < 10 m
(b) 10 m < λ < 10–1 m
–3
Write one use for each.
18 Identify the electromagnetic waves whose wavelengths lie in the range 2
–11 –14
(a) 10 m < λ < 10 m
–4
(b) 10 m < λ < 10 m–6
Write one use of each.
19(a) Long distance radio broadcasts use short-wave bands. Why? 2
(b) The experimental demonstration of electromagnetic waves is possible
only in the low frequency region (the radio wave region). Explain.
20 Name the parts of the electromagnetic spectrum which is 3
(a) suitable for radar systems used in aircraft navigation.
(b) used to treat muscular strain.
(c) used as a diagnostic tool in medicine.
Write in brief, how these waves can be produced.
21 Show that only an accelerated charge can produce an electromagnetic 3
wave.
22 Identify the following electromagnetic radiations as per the wavelengths 3
given below. Write one application of each.
(a) 1 mm (b) 10–12 m (c) 10–8 m
23 Answer the following: 3
(a) Name the em waves which are used for the treatment of certain forms of
cancer. Write their frequency range.
(b) Thin ozone layer on top of stratosphere is crucial for human survival. Why?
(c) Why is the amount of the momentum transferred by the em waves
incident on the surface so small?
24Answer the following: 3
(a) Name the em waves which are suitable for radar systems used in aircraft
navigation. Write the range of frequency of these waves.
(b) If the earth did not have atmosphere, would its average surface
temperature be higher or lower than what it is now? Explain.
(c) An em wave exerts pressure on the surface on which it is incident. Justify.
25 Give reasons for the following: 3
(i) Long distance radio broadcasts use short wave bands.
(ii) The small ozone layer on top of the stratosphere is crucial for human
survival.
(iii) Satellites are used for a long distance TV transmission.
26 Name the radiations of electromagenetic spectrum which are used in 3
(i) warfare to look through fog.
(ii) radar and geostationary satellites.
(iii) stydying the structure and properties of atoms and molecules.
27Show that the sum of conductor current and displacement current has the 3
same value everywhere in the circuit when a parallel capacitor is being
charged by an external source.
28A plane electromagnetic wave, of angular frequency ω is propagating with 3
velocity calong the Z-axis. Write the vector equations of oscillating and
magnetic fields and show these fields diagrammatically.
29Write the generalized expression for the Ampere’s circuital law in terms of the 3
conduction current and the displacement current. Mention the situations
when there is:
(i) only conduction current and no displacement current.
(ii) displacement current and no conduction current.
30 Identify the following electromagnetic radiations as per the wavelengths 3
given below. Write one application of each.
(a) 10–3 nm (b) 10–3 m (c) 1 nm
31Write Maxwell’s generalization of Ampere’s circuital Law. Show that in the 3
process of charging a capacitor, the current produced within the plates of the
capacitor is
where ϕE is the electric flux produced during charging of the capacitor plates.
32 Identify the following electromagnetic radiations as per the frequencies given 3
below. Write one application of each.
(a) 1020 Hz (b) 109 Hz (c) 1011 Hz
33Arrange the following electromagnetic waves in the order of their increasing 3
wavelength:
(a) γ-rays (b) Microwaves (c) X-rays (d) Radio waves
How are infrared waves produced? What role does infrared radiation play in (i)
maintaining the Earth’s warmth, and (ii) physical therapy?
34 (a) How are electromagnetic waves produced by oscillating charges? 3
(b) State clearly how a microwave oven works to heat up a food item
containing water molecules.
(c) Why are microwaves found useful for the radar systems in aircraft
navigation?
35(a) Why are infrared radiations referred to as heat waves? Name the radiations 3
which are next to these radiations in the electromagnetic spectrum having (i)
shorter wavelength, and (ii) longer wavelength.
(b) State the conditions under which a microwave oven heats up a food item
containing water molecules.
36Figure below shows the parts of the electromagnetic spectrum. 3
(i) Name one type of radiation that has
(a) a higher frequency than ultraviolet.
(b) used in luggage security checks at airports
(c) Which part of spectrum is missing in the given figure? Write one use of this
part.
(ii) Some γ-rays emitted from a radioactive source has a speed in air of 3.0 ×
108 m/s and a wavelength of 1.0 × 10–12 m. Calculate the frequency of the g-
rays.
37(a) The speed of an electromagnetic wave in a material medium is given by c 3
= being the permeability of the medium and e is its permittivity. How
does its frequency change?
(b) How are X-rays produced?
(c) Why are microwaves considered suitable for radar systems used in aircraft
navigation?
38An em wave travelling through a medium has electric field vector. 4
Ey = 4 × 105 cos (3.14 × 108 t – 1.57 x) N/C. Here x is in m and t in s.
Then find: (i) wavelength, (ii) frequency, (iii) direction of propagation, (iv)
speed of wave, (v) refractive index of medium, and (vi) amplitude of magnetic
field vector.
39An electric charge is oscillating with a frequency of 3 × 1010 Hz. Calculate the 4
wavelength of the em waves emitted by the oscillating electric charge in
vacuum.
40In 1865, Maxwell discovered the electromagnetic waves and predicted that 5
the light waves were electromagnetic waves. In 1887, Hertz produced and
detected radiowaves (wavelength 6m). Till this time, the only electromagnetic
waves recognised were the visible light and radio waves. In 1895, Indian
physicist JC Bose succeeded in producing and detecting electromagnetic
waves of much shorter wavelength. These waves are called microwaves.
However, like Hertz, his experiment was also confined to the laboratory. In
1899, an Italian engineer Guglielmo Marconi modified Hertz’s experiment, and
successfully sent a wireless signal across English Channel over a distance of
50 km. Marconi’s discovery on the use of em waves for long distance
communication marked the begining of communication using
electromagnetic waves
(i) Electromagnetic waves are produced by
(a) a static charge
(b) a charge moving with constant velocity
(c) an accelerated charge
(d) a neutral particle in motion
(ii) An electromagnetic radiation of frequency v, wavelength λ travelling with a
velocity ‘c’ in air, enters a glass slab of refractive index µ. The frequency,
wavelength and velocity of light in glass slab will be
(iii) The phase and orientation of the magnetic vector associated with
electromagnetic oscillations differ respectively from those of the
corresponding electric vector by
(a) zero and zero
(b) zero and p/2
(c) p/2 and p/2
(d) p/2 and zero
(iv) The structure of solids is investigated by using
(a) cosmic rays
(b) X-rays
(c) microwaves
(d) g-rays
Or
(iv) If λv; λx and λm represent the wavelengths of visible light, X-rays and
microwaves respectively, then
41Waves radiated by accelerated charges and planes through space as coupled 5
electric and magnetic fields, vibrating in perpendicular planes are called
electromagnetic waves. The electromagnetic waves are orderly distributed
according to their frequency or wavelength, into different groups. These
groups have distinct properties and constitute an electromagnetic spectrum.
(ii) The electric and magnetic fields in an e.m. wave
(a) have same phase
(b) have same amplitudes
(c) have different phase
(d) have same planes of vibration
(iii) The magnetic field vector of a plane electromagnetic wave oscillates with
a frequency of 4 × 1010 Hz. What is the wavelength?
(a) 6.67 × 10–3 m (b) 0.75 × 10–2 m
(c) 7.5 × 10–4 m (d) 6.67 × 10–5 m
(iv) The em waves with longest frequency are
(a) Radio waves
(b) Infrared waves
(c) X-rays
(d) g-rays
Or
(iv) Radiations of which of following electromagnetic waves group is used in
preservation of food?
(a) Ultraviolet rays
(b) X-rays
(c) Visible rays
(d) Infrared rays
42Oscillating charge: A oscillating charge is an example of accelerating charge. 5
It produces an oscillating electric field in space, which produces an oscillating
magnetic field, which in turn produces an oscillating electric field and so on.
The oscillating electric and magnetic fields regenerate each other as a wave
which propagates through space
(i) Which of the following can be used to produce a propagating electromagnetic wave?
(a) A chargeless particle
(b) An accelerating charge
(c) A charge moving at constant velocity
(d) A stationary charge
(ii) If we want to produce electromagnetic waves of wavelength 500 km by an
oscillating charge than frequency of oscillating charge must be
(a) 600 Hz
(b) 500 Hz
(c) 167 Hz
(d) 15 Hz
(iii) A plane electromagnetic wave propagating along x-direction can have the
following pairs of E and B
(a) Ex, By
(b) Ey, Bz
(c) Bx, Ey
(d) Ez, By
iv) Displacement current exists only when
(a) Electric field is changing
(b) Magnetic field is changing
(c) Electric field is not changing
(d) Magnetic field is not changing
Or
(iv) Electromagnetic waves used as a diagnostic tool in medical are:
(a) X-rays
(b) UV rays
(c) IR rays
(d) Ultrasonic waves
43 In electromagnetic wave if ue and um are mean electric and magnetic energy 1
densities respectively, then
44 Which of the following is called heat radiation? 1
(a) X-rays (b) γ-rays
(c) Infrared radiation (d) Microwave
45 From Maxwell’s hypothesis, a charging electric field gives rise to 1
(a) an electric field. (b) an induced emf.
(c) a magnetic field. (d) a magnetic dipole.
46 Electromagnetic waves are transverse in nature is evident by 1
(a) polarisation. (b) interference.
(c) reflection. (d) diffraction.
47 Which of the following are not electromagnetic waves? 1
(a) Cosmic rays (b) γ-rays
(c) β-rays (d) X-rays
48 10 cm is a wavelength corresponding to the spectrum of 1
(a) infrared rays (b) ultraviolet rays
(c) microwaves (d) X-rays
49If represent electric and magnetic field vector of the electromagnetic 1
waves then the direction of propagation of the em wave is that of
50 The structure of solids is investigated by using 1
(a) cosmic rays (b) X-rays
(c) γ-rays (d) infrared rays
51 The condition under which a microwave over heats up a food item containing 1
water molecules most efficiently is
(a) The frequency of the microwaves must match the resonant frequency of
the water molecules.
(b) The frequency of the microwaves has no relation with natural frequency of
the water molecules.
(c) Microwaves are heat waves, so always produce heating.
(d) Infrared waves produce heating in a microwave oven.
52 Which radiations are used in treatment of muscle ache? 1
(a) Infrared (b) Ultraviolet
(c) Microwave (d) X-rays
53 The correct option, if speeds of gamma rays, X-rays and microwave are Vg, Vx 1
and Vm respectively will be.
(a) Vg > Vx > Vm (b) Vg < Vx < Vm
(c) Vg > Vx > Vm (d) Vg = Vx = Vm
54 Waves in decreasing order of their wavelength are 1
(a) X-rays, infrared rays, visible rays, radio waves
(b) radio waves, visible rays, infrared rays, X-rays.
(c) radio waves, infrared rays, visible rays, X-rays.
(d) radio waves, ultraviolet rays, visible rays, X-rays.
55 1
56 Electromagnetic waves with wavelength λ are used by a FM radio station for 1
broadcasting. Here λ belongs to
(a) radio waves (b) VHF radio waves
(c) UHF radio waves (d) microwaves
57The oscillating magnetic field in a plane electromagnetic wave is given as By = 1
(8 × 10–6) sin [2 × 1011 t + 300πx] T, wavelength of the em wave is
(a) 0.80 cm (b) 1 × 103 m
(c) 2 × 10–2 cm (d) 0.67 cm
58One requires 11 eV of energy to dissociate a carbon monoxide molecule into 1
carbon and oxygen atoms. The minimum frequency of the appropriate
electromagnetic radiation to achieve the dissociation lies in
(a) visible region. (b) infrared region.
(c) ultraviolet region. (d) microwave region.
59 The ratio of contributions made by the electric field and magnetic field 1
components to the intensity of an EM wave is
60 Speed of electromagnetic wave related to electric field and magnetic field 1
vector in vacuum.
61 Which of the following statement is false for the properties of em waves? 1
(a) The energy of em wave is divided equally between electric and magnetic
fields.
(b) Both electric and magnetic field vectors are parallel to each and
perpendicular to the direction of propagation of wave.
(c) These waves do not require any material medium for propagation.
(d) Both electric and magnetic field vectors attain the maximum and
minimum at the same place and same time.
62 A radiation of energy ‘E’ falls normally on a perfectly reflecting surface. The 1
momentum transferred to the surface is
63 Radio waves are produced by 1
(a) accelerated motion of electrons in oscillating circuits.
(b) sudden deceleration of fast moving electrons by metal target
(c) heating of certain substances at particular temperature.
(d) de excitation of electron from higher energy orbital to lower one.
64 represent electric and magnetic fields of an electromagnetic wave 1
respectively. The direction of propagation of the wave is along
65A 70 kg astronaut stranded in space chooses to use his flashlight to move 1
himself. If his flashlight can flash a 12 W light beam in space in a fixed
direction so that he acquires momentum in the opposite direction, how much
time do you think will he take to attain a speed of 2 m/s?
(a) 3.5 × 109 s
(b) 11.6 s
(c) 3.8 × 10–8 s
(d) Infinite
66 In a electromagnetic wave, if ue and um are mean electric and magnetic 1
energy densities respectively, then
67The electric field associated with an e.m wave in vacuum is given by = 40 1
cos (kz – 6 × 108 t) , where E, Z and t are in volt/m, metre and seconds
respectively. The value of wave vector K is
(a) 2 m–1
(b) 0.5 m–1
(c) 6 m–1
(d) 3 m–1
68Light with an energy flux of 20 W/cm2 falls on a non-reflecting surface at 1
normal incidence. If the surface has an area of 30 cm2, the total momentum
delivered (for complete absorption) during 30 minutes is
(a) 36 × 10–5 kg m/s.
(b) 36 × 10–4 kg m/s.
(c) 108 × 104 kg m/s.
(d) 1.08 × 107 kg m/s.
69The electric field intensity produced by the radiations coming from 100 W bulb 1
at a 3 m distance is E. The electric field intensity produced by the radiations
coming from 50 W bulb at the same distance is
70If E and B represent electric and magnetic field vectors of the electromagnetic 1
wave, the direction of propagation of electromagnetic wave is along
(a) E.
(b) B.
(c) B × E.
(d) E × B.
71An EM wave radiates outwards from a dipole antenna, with E0 as the 1
amplitude of its electric field vector. The electric field E0 which transports
significant energy from the source falls off as
72For the following questions, two statements are given–one labelled Assertion 1
(a) and the other labelled Reason (R). Select the correct answer to these
questions from the codes (a), (b), (c) and (d) as given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
Assertion: Displacement current arises on account of change in electric flux.
Reason:
73For the following questions, two statements are given–one labelled Assertion 1
(a) and the other labelled Reason (R). Select the correct answer to these
questions from the codes (a), (b), (c) and (d) as given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
Assertion: Electromagnetic waves exert radiation pressure.
Reason: This is because they carry energy.
74For the following questions, two statements are given–one labelled Assertion 1
(a) and the other labelled Reason (R). Select the correct answer to these
questions from the codes (a), (b), (c) and (d) as given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
Assertion: Microwaves have more energy than the radio waves.
Reason: E = hv
75For the following questions, two statements are given–one labelled Assertion 1
(a) and the other labelled Reason (R). Select the correct answer to these
questions from the codes (a), (b), (c) and (d) as given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
Assertion: In an electromagnetic waves magnitude of magnetic field is less
than the magnitude of electric field.
Reason:
76For the following questions, two statements are given–one labelled Assertion 1
(a) and the other labelled Reason (R). Select the correct answer to these
questions from the codes (a), (b), (c) and (d) as given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
Assertion: The velocity of all electromagnetic waves in vacuum is different.
Reason: Because all waves are of different frequency.
77For the following questions, two statements are given–one labelled Assertion 1
(a) and the other labelled Reason (R). Select the correct answer to these
questions from the codes (a), (b), (c) and (d) as given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
Assertion: Electromagnetic waves do not require any medium to travel.
Reason: Electromagnetic waves cannot travel through any medium.
78 1
79 A plane electromagnetic wave propagating along x direction can have the 1
following pairs of E and B
(a) Ex, By. (b) Ey, Bz.
(c) Bx, Ey. (d) None of these
80A charged particle oscillates about its mean equilibrium position with a 1
frequency of 109 Hz. For producing electromagnetic waves which one is not
true?
(a) They will have frequency of 109 Hz.
(b) They will have frequency of 2 × 109 Hz.
(c) They will have a wavelength of 0.3 m.
(d) They fall in the region of radio waves.
81 The source of electromagnetic waves can be a charge 1
(a) moving with a constant velocity.
(b) moving in a circular orbit.
(c) at rest.
(d) falling in a magnetic field.
82 Which of the following has minimum wavelength? 1
(a) Blue light (b) γ-rays
(c) infrared rays (d) microwave
83 Which of the following has maximum penetrating power? 1
(a) Ultraviolet radiation (b) Microwaves
(c) γ-rays (d) Radio waves
84For the following questions, two statements are given–one labelled Assertion 1
(a) and the other labelled Reason (R). Select the correct answer to these
questions from the codes (a), (b), (c) and (d) as given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
Assertion: The ozone layer present at the top of the stratosphere is very
crucial for human survival.
Reason: Ozone layer prevents IR radiation.
85For the following questions, two statements are given–one labelled Assertion 1
(a) and the other labelled Reason (R). Select the correct answer to these
questions from the codes (a), (b), (c) and (d) as given below.
(a) Both A and R are true and R is the correct explanation of A.
(b) Both A and R are true but R is NOT the correct explanation of A.
(c) A is true but R is false.
(d) A is false and R is also false.
Assertion: Microwaves are considered suitable for radar systems.
Reason: Microwaves are of shorter wavelength.
86A linearly polarized electromagnetic wave given as E = cos (kz – ωt) is 1
incident normally on a perfectly reflecting infinite wall at z = a. Assuming that
the material of the wall is optically inactive, the reflected wave will be given as
(a) Er = – cos(kz – ωt).
(b) Er = cos(kz + ωt).
(c) Er = – cos(kz + ωt).
(d) Er = sin(kz – ωt).
87An electromagnetic wave travelling along z-axis is given as: E = E0 cos (kz – 1
ωt). Choose the incorrect option from the following;
(a) The associated magnetic field is given as
(b) The electromagnetic field can be written in terms of the associated
magnetic field as
88Electromagnetic waves travelling in a medium having relative permeability µr = 1
1.3 and relative permittivity Er = 2.14. The speed of electromagnetic waves in
medium must be
(a) 1.8 × 108 ms–1 (b) 1.8 × 104 ms–1
(c) 1.8 × 106 ms–1 (d) 1.8 × 102 ms–1
89 In electromagnetic waves the phase difference between electric and 1
magnetic field vectors are
90 The quantity represents 1
(a) speed of sound
(b) speed of light in vacuum
(c) speed of e.m.w.
(d) inverse of speed of light in vacuum
