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Year: 2025
Topic: Electromagnetic waves
1.
The electric field in a plane electromagnetic wave is given by
\(\text{E}_\text{z}\,=\,60\, \text{cos}\left(5\text{x}\,+\,1.5 \times 10^9 \text{t}\right)\,\text{V/m}\).
Then the expression for the corresponding magnetic field is (here subscripts denote the direction of the field):
(1).
\(\text{B}_\text{y}\,=\,60\, \text{sin}\left(5\text{x}\,+\,1.5 \times 10^9 \text{t}\right)\,\text{T}\)
(2).
\(\text{B}_\text{y}= 2\times 10^{-7}\)\(\text{cos}\left(5\text{x}+1.5 \times 10^9 \text{t}\right)\text{T}\)
(3).
\(\text{B}_\text{x}= 2\times 10^{-7}\)\(\text{cos}\left(5\text{x}+1.5 \times 10^9 \text{t}\right)\,\text{T}\)
(4).
\(\text{B}_\text{z}\,=\,60\, \text{sin}\left(5\text{x}\,+\,1.5 \times 10^9 \text{t}\right)\,\text{T}\)

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Year: 2023
Topic: Electromagnetic waves
2.
An ac source is connected to a capacitor C. Due to decrease in itsoperating frequency
(1).
Displacement current increases
(2).
Displacement current decreases
(3).
Capacitive reactance remains constant
(4).
Capacitive reactance decreases

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Year: 2021
Topic: Electromagnetic waves
3.
An electromagnetic wave of wavelength ' λ ' is incident on a photosensitive surface of negligible work function. If ' m ' mass is of photoelectron emitted from the surface has de-Broglie wavelength \(λ_d\) , then
(1).
\(\displaystyle λ\,=\,\left(\frac{2m}{hc}\right)λ_d^2\)
(2).
\(\displaystyle λ_d\,=\,\left(\frac{2mc}{h}\right)λ^2\)
(3).
\(\displaystyle λ\,=\,\left(\frac{2mc}{h}\right)λ_d^2\)
(4).
\(\displaystyle λ\,=\,\left(\frac{2h}{mc}\right)λ_d^2\)

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Year: 2025
Topic: Electromagnetic waves
4.
An electron (mass \(9 \times 10^{-31} \text{kg}\) and charge \(1.6 \times 10^{-19}\text{C}\)) moving with speed c/100 (c = speed of light) is injected into a magnetic field \(\vec{\text{B}}\) of magnitude \(9 \times 10^{-4}\text{T}\) perpendicular to its direction of motion. We wish to apply an uniform electric field \(\vec{\text{E}}\) together with the magnetic field so that the elctron does not deflect from its path. Then (speed of light \(c = 3 \times 10^8 \text{ms}^{-1}\))
(1).
\(\vec{\text{E}}\) is parallel to \(\vec{\text{B}}\) and its magnitude is \(27 \times 10^4 \text{V m}^{-1}\)
(2).
\(\vec{\text{E}}\) is perpendicular to \(\vec{\text{B}}\) and its magnitude is \(27 \times 10^4 \text{V m}^{-1}\)
(3).
\(\vec{\text{E}}\) is perpendicular to \(\vec{\text{B}}\) and its magnitude is \(27 \times 10^2 \text{V m}^{-1}\)
(4).
\(\vec{\text{E}}\) is parallel to \(\vec{\text{B}}\) and its magnitude is \(27 \times 10^2 \text{V m}^{-1}\)

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Year: 2025
Topic: Electromagnetic waves
5.
A parallel plate capacitor made of circular plates is being charged such that the surface charge density on its plates is increasing at a constant rate with time. The magnetic field arising due to displacement current is:
(1).
Zero between the plates and non-zero outside
(2).
Zero at all places
(3).
Constant between the plates and zero outside the plates
(4).
Non-zero everywhere with maximum at the imaginary cylindrical surface connecting peripheries of the plates

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Year: 2024
Topic: Electromagnetic waves
6.
The property which is not of an electromagnetic wave travelling in free space is that:
(1).
They are transverse in nature
(2).
The energy density in electric field is equal to energy density in magnetic field
(3).
They travel with a speed equal to \(\frac{1}{\sqrt{\mu_0\epsilon_0}}\)
(4).
They originate from charges moving with uniform speed

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Year: 2023
Topic: Electromagnetic waves
7.
In a plane electromagnetic wave travelling in free space, the electric field component oscillates sinusoidally at a frequency of \(2.0 \times10^{10}\) Hz and amplitude \(48\,Vm^{−1}\). Then the amplitude of oscillating magnetic field is (Speed of light in free space = \( 3 \times 10^8\, ms^{−1}\))
(1).
\(1.6 \times 10^{−8}\,T\)
(2).
\(1.6 \times 10^{−7}\,T\)
(3).
\(1.6 \times 10^{−6}\,T\)
(4).
\(1.6 \times 10^{−9}\,T\)

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Year: 2023
Topic: Electromagnetic waves
8.
The minimum wavelength of X-rays produced by an electron acceleratedthrough a potential difference of V volts is proportional to
(1).
\(\displaystyle \frac{1}{V}\)
(2).
\(\displaystyle \frac{1}{\sqrt{V}}\)
(3).
\(\displaystyle V^2\)
(4).
\(\displaystyle \sqrt{V}\)

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Year: 2022
Topic: Electromagnetic waves
9.
Match List-I with List-II
(1).
(a) - (iv), (b) - (iii), (c) - (ii), (d) - (i)
(2).
(a) - (iii), (b) - (ii), (c) - (i), (d) - (iv)
(3).
(a) - (iii), (b) - (iv), (c) - (ii), (d) - (i)
(4).
(a) - (ii), (b) - (iii), (c) - (iv), (d) - (i)

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Year: 2022
Topic: Electromagnetic waves
10.
When light propagates through a material medium of relative permittivity \(\epsilon_r\) and relative permeability \(\mu_r\), the velocity of light, v is given by (c-velocity of light in vacuum)
(1).
v = c
(2).
\(\displaystyle v=\sqrt{\frac{µ_r}{ε_r}}\)
(3).
\(\displaystyle v=\sqrt{\frac{ε_r}{µ_r}}\)
(4).
\(\displaystyle v=\frac{c}{\sqrt{ε_rµ_r}}\)

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Year: 2021
Topic: Electromagnetic waves
11.
For a plane electromagnetic wave propagating in x-direction, which oneof the following combination gives the correct possible directions forelectric field (E) and magnetic field (B) respectively?
(1).
\(\hat{j}+\hat{k},\, \hat{j}+\hat{k}\)
(2).
\(-\hat{j}+\hat{k}, \, -\hat{j}-\hat{k}\)
(3).
\(\hat{j}+\hat{k}, \, -\hat{j}-\hat{k}\)
(4).
\(-\hat{j}+\hat{k}, \, \hat{j}-\hat{k}\)

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Year: 2020
Topic: Electromagnetic waves
12.
Light with an average flux of \(20\, \text{W}/cm^2\) falls on a non-reflecting surface at normal incidence having surface area \(20\,cm^2\). The energy recieved by the surface during time span of 1 minute is
(1).
\(12 \times\ 10^3\) J
(2).
\(24 \times\ 10^3\) J
(3).
\(48 \times\ 10^3\) J
(4).
\(10 \times\ 10^3\) J

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Solution
Year: 2020
Topic: Electromagnetic waves
13.
The ratio of contributions made by the electric field and magnetic field components to the intensity of an electromagnetic wave is : ( c = speed of electromagnetic waves)
(1).
\(1 : 1\)
(2).
\(1 : c\)
(3).
\(1 : c^2\)
(4).
\(c : 1\)

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Year: 2019
Topic: Electromagnetic waves
14.
A parallel plate capacitor of capacitance 20µF is being charged by a voltage source whose potential is changing at the rate of 3V ∕ s. The conduction current through the connecting wires, and the displacement current through the plates of the capacitor, would be, respectively
(1).
zero, zero
(2).
zero, 60µA
(3).
60µA, 60µA
(4).
60µA, zero

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Year: 2018
Topic: Electromagnetic waves
15.
An em wave is propagating in a medium with a velocity \(\vec{v}=v\,\hat{i}\). The instantaneous oscillating electric field of this em wave is along +y axis. Then the direction of oscillating magnetic field of the em wave will be along
(1).
−z direction
(2).
+z direction
(3).
−y direction
(4).
−x direction

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Year: 2017
Topic: Electromagnetic waves
16.
In an electromagnetic wave in free space the root mean square value of the electric field is \(E_{rms}\,=\, 6V m^{−1}\).The peak value of the magnetic field is
(1).
\(2.83 \times 10^{−8}\,T\)
(2).
\(0.70 \times 10^{−8}\,T\)
(3).
\(4.23 \times 10^{−8}\,T\)
(4).
\(1.41 \times 10^{−8}\,T\)

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Year: 2016
Topic: Electromagnetic waves
17.
Out of the following options which one can be used to produce a propagating electromagnetic wave?
(1).
A chargeless particle
(2).
An accelerating charge
(3).
A charge moving at constant velocity
(4).
A stationary charge

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