Question 1: Palette 1/48

Allen MCQ

If $\vec{E}$ and $\vec{B}$ are the electric and magnetic field vectors of electromagnetic waves then the direction of propagation of electromagnetic wave is along the direction of -

A

$\vec{E}$

B

$\vec{B}$

C

$\vec{E} \times \vec{B}$

D

none of these

Question 2: Palette 2/48

Allen MCQ

The electromagnetic waves do not transport -

A

energy

B

charge

C

momentum

D

information

Question 3: Palette 3/48

Allen MCQ

The wave function (in S.I. units) for an electromagnetic wave is given as - $\psi (\mathrm{x},\mathrm{t}) = 10^{3}\sin \pi (3\times 10^{6}\mathrm{x} - 9\times 10^{14}\mathrm{t})$ The speed of the wave is -

A

$9\times 10^{14}\mathrm{m / s}$

B

$3\times 10^{8}\mathrm{m / s}$

C

$3\times 10^{6}\mathrm{m / s}$

D

$3\times 10^{7}\mathrm{m / s}$

Question 4: Palette 4/48

Allen MCQ

In the above problem, wavelength of the wave is -

A

$666\mathrm{nm}$

B

$666 Å$

C

$666\mu \mathrm{m}$

D

$6.66\mathrm{nm}$

Question 5: Palette 5/48

Allen MCQ

In an electromagnetic wave the average energy density is associated with -

A

electric field only

B

magnetic field only

C

equally with electric and magnetic fields

D

average energy density is zero

Question 6: Palette 6/48

Allen MCQ

In an electromagnetic wave the energy density associated with magnetic field will be

A

$\frac{1}{2}Ll^{2}$

B

$\frac{B^{2}}{2\mu_{0}}$

C

$\frac{1}{2}\mu_{0}B^{2}$

D

$\frac{1}{2}\frac{\mu_{0}}{B^{2}}$

Question 7: Palette 7/48

Allen MCQ

In the above problem, the energy density associated with the electric field will be -

A

$\frac{1}{2}CV^{2}$

B

$\frac{1}{2}\frac{q^{2}}{C}$

C

$\frac{1}{2}\frac{\varepsilon^{2}}{E}$

D

$\frac{1}{2}\varepsilon_{0}E^{2}$

Question 8: Palette 8/48

Allen MCQ

If there were no atmosphere, the average temperature on earth surface would be -

A

lower

B

higher

C

same

D

0°C

Question 9: Palette 9/48

Allen MCQ

In which part of earth's atmosphere is the ozone layer present?

A

troposphere

B

stratosphere

C

ionosphere

D

mesosphere

Question 10: Palette 10/48

Allen MCQ

The ozone layer is earth's atmosphere is crucial for human survival because it –

A

contains ions

B

reflects radio signals

C

reflects ultraviolet rays

D

reflects infrared rays

Question 11: Palette 11/48

Allen MCQ

The frequency from $3 \times 10^{9}$ Hz to $3 \times 10^{10}$ Hz is –

A

high frequency band

B

super high frequency band

C

ultra high frequency band

D

very high frequency band

Question 12: Palette 12/48

Allen MCQ

The frequency from 3MHz to 30 MHz is known as -

A

audio band

B

medium frequency band

C

very high frequency band

D

high frequency band

Question 13: Palette 13/48

Allen MCQ

The AM range of radiowaves have frequency –

A

less than 30 MHz

B

more than 30 MHz

C

less than 20000Hz

D

more than 20000Hz

Question 14: Palette 14/48

Allen MCQ

Select wrong statement from the following for EMW-

A

are transverse

B

travel with same speed in all medium

C

travel with the speed of light

D

are produced by accelerating charge

Question 15: Palette 15/48

Allen MCQ

The waves related to tele-communication are -

A

infrared

B

visible light

C

microwaves

D

ultraviolet rays

Question 16: Palette 16/48

Allen MCQ

The nature of electromagnetic wave is –

A

longitudinal

B

longitudinal stationary

C

transverse

D

transverse stationary

Question 17: Palette 17/48

Allen MCQ

Greenhouse effect keeps the earth surface –

A

cold at night

B

dusty and cold

C

warm at night

D

moist

Question 18: Palette 18/48

Allen MCQ

The speed of electromagnetic radiation in vacuum is:-

A

$\mu_{0}\varepsilon_{0}$

B

$\sqrt{\mu_{0}\varepsilon_{0}}$

C

$\frac{1}{\mu_{0}\varepsilon_{0}}$

D

$\frac{1}{\sqrt{\mu_{0}\varepsilon_{0}}}$

Question 19: Palette 19/48

Allen MCQ

What is the cause of greenhouse effect?

A

Infrared rays

B

Ultraviolet rays

C

X-rays

D

Radio waves

Question 20: Palette 20/48

Allen MCQ

The conduction current is the same as displacement current when source is :-

A

ac only

B

dc only

C

both ac and dc

D

neither dc nor ac

Question 21: Palette 21/48

Allen MCQ

The energy of the em waves is of the order of 15 keV. To which part of the spectrum does it belong?

A

γ-rays

B

X-rays

C

Infra-red rays

D

Ultraviolet rays

Question 22: Palette 22/48

Allen MCQ

A radiation of energy 'E' falls normally on a perfectly reflecting surface. The momentum transferred to the surface is (c = Speed of light) :-

A

$\frac{2E}{c}$

B

$\frac{2E}{c^{2}}$

C

$\frac{E}{c^{2}}$

D

$\frac{E}{c}$

Question 23: Palette 23/48

Allen MCQ

Out of the following options which one can be used to produce a propagating electromagnetic wave?

A

A charge moving at constant velocity

B

A stationary charge

C

A chargeless particle

D

An accelerating charge

Question 24: Palette 24/48

Allen MCQ

A 100 Ω resistance and a capacitor of 100 Ω reactance are connected in series across a 220 V source. When the capacitor is 50% charged, the peak value of the displacement current is :-

A

4.4 A

B

$11\sqrt{2}$ A

C

2.2 A

D

11 A

Question 25: Palette 25/48

Allen MCQ

In an electromagnetic wave in free space the root mean square value of the electric field is $E_{rms} = 6V/m$ . The peak value of the magnetic field is :-

A

$2.83 \times 10^{-8}$ T

B

$0.70 \times 10^{-8}$ T

C

$4.23 \times 10^{-8}$ T

D

$1.41 \times 10^{-8}$ T

Question 26: Palette 26/48

Allen MCQ

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 :-

A

-z direction

B

+z direction

C

-y direction

D

-x direction

Question 27: Palette 27/48

Allen MCQ

For a transparent medium relative permeability and permittivity, $\mu_{r}$ and $\epsilon_{r}$ are 1.0 and 1.44 respectively. The velocity of light in this medium would be,

A

$2.5 \times 10^{8}$ m/s

B

$3 \times 10^{8}$ m/s

C

$2.08 \times 10^{8}$ m/s

D

$4.32 \times 10^{8}$ m/s

Question 28: Palette 28/48

Allen MCQ

Light with an average flux of $20 \, W/cm^{2}$ falls on a non-reflecting surface at normal incidence having surface area $20 \, cm^{2}$ . The energy received by the surface during time span of 1 minute is:

A

$48 \times 10^{3}$ J

B

$10 \times 10^{3}$ J

C

$12 \times 10^{3}$ J

D

$24 \times 10^{3}$ J

Question 29: Palette 29/48

Allen MCQ

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)

A

$1 : c^{2}$

B

c : 1

C

1 : 1

D

1 : c

Question 30: Palette 30/48

Allen MCQ

The E.M. wave with shortest wavelength among the following is

A

Ultraviolet rays

B

X-rays

C

Gamma-rays

D

Microwaves

Question 31: Palette 31/48

Allen MCQ

The magnetic field in a plane electromagnetic wave is given by: $B_y = 2 \times 10^{-7} \sin (\pi \times 10^3 x + 3\pi \times 10^{11} t) T$ Calculate the wavelength.

A

$\pi \times 10^3 m$

B

$2 \times 10^{-3} m$

C

$2 \times 10^3 m$

D

$\pi \times 10^{-3} m$

Question 32: Palette 32/48

Allen MCQ

A capacitor of capacitance 'C', is connected across an ac source of voltage V, given by $V = V_{0} \sin \omega t$ . The displacement current between the plates of the capacitor, would then be given by:

A

$I_{d} = V_{0} \omega C \cos \omega t$

B

$I_{d} = \frac{V_{0}}{\omega C} \cos \omega t$

C

$I_{d} = \frac{V_{0}}{\omega C} \sin \omega t$

D

$I_{d} = V_{0} \omega C \sin \omega t$

Question 33: Palette 33/48

Allen MCQ

For a plane electromagnetic wave propagating in x-direction, which one of the following combinations gives the correct possible directions for electric field (E) and magnetic field (B) respectively?

A

$\hat{j} + \hat{k}, \hat{j} + \hat{k}$

B

$-\hat{j} + \hat{k}, -\hat{j} - \hat{k}$

C

$\hat{j} + \hat{k}, -\hat{j} - \hat{k}$

D

$-\hat{j} + \hat{k}, -\hat{j} + \hat{k}$

Question 34: Palette 34/48

Allen MCQ

When light propagates through a material medium of relative permittivity $\varepsilon_{r}$ and relative permeability $\mu_{r}$ , the velocity of light, v is given by: (c = velocity of light in vacuum)

A

$v = \sqrt{\frac{\mu_{r}}{\varepsilon_{r}}}$

B

$v = \sqrt{\frac{\varepsilon_{r}}{\mu_{r}}}$

C

$v = \frac{c}{\sqrt{\varepsilon_{r}\mu_{r}}}$

D

v = c

Question 35: Palette 35/48

Allen Match the Columns

Match Column-I(Electromagnetic waves) with Column-II(Wavelength)

Column-I	Column-II
(A) AM radio waves (B) Microwaves (C) Infrared radiations (D) X-rays	(P) $10^{-10}$ m (Q) $10^{2}$ m (R) $10^{-2}$ m (S) $10^{-4}$ m

A

A - R, B - Q, C - P, D - S

B

A - R, B - S, C - Q, D - P

C

A - Q, B - R, C - S, D - P

D

A - S, B - R, C - Q, D - P

Question 36: Palette 36/48

Allen MCQ

The magnetic field of a plane electromagnetic wave is given by $\vec{B}=3\times10^{-8}\cos(1.6\times10^{3}x+48\times10^{10}t)\hat{j}$ , then the associated electric field will be:

A

$3\times10^{-8}\cos(1.6\times10^{3}x+48\times10^{10}t)\hat{i}V/m$

B

$3\times10^{-8}\sin(1.6\times10^{3}x+48\times10^{10}t)\hat{i}V/m$

C

$9\sin(1.6\times10^{3}x-48\times10^{10}t)\hat{k}V/m$

D

$9\cos(1.6\times10^{3}x+48\times10^{10}t)\hat{k}V/m$

Question 37: Palette 37/48

Allen MCQ

The ratio of the magnitude of the magnetic field and electric field intensity of a plane electromagnetic wave in free space of permeability $\mu_0$ and permittivity $\varepsilon_0$ is (c - velocity of light in free space)

A

c

B

$\frac{1}{c}$

C

$\frac{c}{\sqrt{\mu_0\varepsilon_0}}$

D

$\frac{\sqrt{\mu_0\varepsilon_0}}{c}$

Question 38: Palette 38/48

Allen MCQ

In a plane electromagnetic wave travelling in free space, the electric field component oscillates sinusoidally at a frequency of $2.0 \times 10^{10}$ Hz and amplitude 48 Vm $^{-1}$ . Then the amplitude of oscillating magnetic field is: (Speed of light in free space = $3 \times 10^{8}$ m s $^{-1}$ )

A

$1.6 \times 10^{-8}$ T

B

$1.6 \times 10^{-7}$ T

C

$1.6 \times 10^{-6}$ T

D

$1.6 \times 10^{-9}$ T

Question 39: Palette 39/48

Allen MCQ

$\epsilon_0$ and $\mu_0$ are the electric permittivity and magnetic permeability of free space respectively. If the corresponding quantities of a medium are $2\epsilon_0$ and $1.5\mu_0$ respectively, the refractive index of the medium will nearly be :

A

$\sqrt{2}$

B

$\sqrt{3}$

C

3

D

2

Question 40: Palette 40/48

Allen MCQ

To produce an instantaneous displacement current of 2 mA in the space between the parallel plates of a capacitor of capacitance 4 μF, the rate of change of applied variable potential difference ( $\frac{dV}{dt}$ ) must be:

A

800 V/s

B

500 V/s

C

200 V/s

D

400 V/s

Question 41: Palette 41/48

Allen MCQ

A parallel plate capacitor is charged by connecting it to a battery through a resistor. If I is the current in the circuit, then in the gap between the plates:

A

there is no current.

B

displacement current of magnitude equal to I flows in the same direction as I.

C

displacement current of magnitude equal to I flows in a direction opposite to that of I.

D

displacement current of magnitude greater than I flows but can be in any direction.

Question 42: Palette 42/48

Allen MCQ

The property which is not of an electromagnetic wave travelling in free space is that:

A

they are transverse in nature.

B

the energy density in electric field is equal to energy density in magnetic field.

C

they travel with a speed equal to $\frac{1}{\sqrt{\mu_{0} \in_{0}}}$

D

they originate from charges moving with uniform speed.

Question 43: Palette 43/48

Allen MCQ

The electromagnetic radiation which has the smallest wavelength are :

A

X-rays

B

Gamma rays

C

Ultraviolet rays

D

Microwaves

Question 44: Palette 44/48

Allen MCQ

If the ratio of relative permeability and relative permittivity of a uniform medium is 1:4. The ratio of the magnitudes of electric field intensity (E) to the magnetic field intensity (H) of an EM wave propagating in that medium is $\left(\text{Given that } \sqrt{\frac{\mu_0}{\varepsilon_0}} = 120\pi\right)$ :

A

$30\pi:1$

B

$1:120\pi$

C

$60\pi:1$

D

$120\pi:1$

Question 45: Palette 45/48

Allen MCQ

For EM waves
(a) $\gamma $ rays have higher penetrating power than x rays
(b) x rays have higher penetrating power than $\gamma $ rays
(c) Infrared has higher wavelength than x-rays
(d) Range of visible light is 4000 Å to 7000 Å then correct options are

A

a, b and d

B

a, c and d

C

a and c

D

a, b and d

Question 46: Palette 46/48

Allen MCQ

Electric field associated with EM wave in free space is given by $\vec{E}=30\sin\left(6\times10^{8}t+kz\right)\hat{i}$ then match the following columns.

Column-I	Column-II
(A) Direction of propagation of EM wave (B) Wave length of EM wave (C) Direction of magnetic field of EM wave (D) Propagation constant ‘K’ of EM wave	(P) −y axis (Q) $2\ \mathrm{m}^{-1}$ (R) $3.14\ \mathrm{m}$ (S) ‘−z’ axis

A

A-P, B-R, C-S, D-R

B

A-S, B-R, C-P, D-Q

C

A-P, B-Q, C-S, D-S

D

A-S, B-R, C-P, D-P

Question 47: Palette 47/48

Allen MCQ

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): MRI is less harmful medical diagnosis technique than CT-scan
Reason (R): X-rays are used in CT-scan, while MRI uses radio waves.
In the light of the above statements,
choose the most appropriate answer from the options given below:

A

Both (A) and (R) are true and (R) is the correct explanation of (A).

B

Both (A) and (R) are true and (R) is NOT the correct explanation of (A).

C

(A) is true but (R) is false.

D

(A) is false but (R) is true.

Question 48: Palette 48/48

Allen Match the Columns

Match the Column-I (Law) with Column-II (Mathematical formula)

Column-I	Column-II
(A) Faraday law (B) Ampere Maxwell law (C) Gauss law for magnetism (D) Gauss law for electrostatics	(P) $\oint \vec{E}\cdot d\vec{A}=\frac{q}{\varepsilon_0}$ (Q) $\oint \vec{B}\cdot d\vec{A}=0$ (R) $\oint \vec{E}\cdot d\vec{\ell}=-\frac{d\phi_B}{dt}$ (S) $\oint \vec{B}\cdot d\vec{\ell}=\mu_0 i+\varepsilon_0\mu_0\frac{d\phi_E}{dt}$

A

A → R, B → Q, C → S, D → P

B

A → P, B → Q, C → S, D → R

C

A → P, B → S, C → Q, D → R

D

A → R, B → S, C → Q, D → P