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JEE • PHYSICS • ELECTROMAGNETIC WAVES

Electromagnetic waves practice · Easy

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Practice format and chapter quiz

These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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1 Easy

1 of 18

Understanding +4 | -1

Let the velocities of light in vacuum and glass are represented by

v

and

v_{\mathrm{g}}

. When electrons move through glass with a velocity

v_e

, there emitted a visible radiation in glass if

View answer and explanation

Correct option: A

v_e > v_g

Option A is correct because visible radiation (Cherenkov radiation) is emitted when a charged particle travels through a dielectric medium faster than the speed of light in that medium.

2 Easy

2 of 18

Application +4 | -1

The frequency of a plane electromagnetic wave traveling in vacuum in X-direction is
30 MHz, its wavelength is

View answer and explanation

Correct option: C

10 m

Option C (10 m) is correct because the wavelength is calculated using the formula

\lambda = c/f

, where c is the speed of light and f is the frequency.

3 Easy

3 of 18

Application +4 | -1

A new system of units is evolved in which the values of

{\mu _0}

and

{\varepsilon _0}

are 2 and 8 respectively. Then the speed of light in this system will be

View answer and explanation

Correct option: A

0.25

Option A (0.25) is correct because the speed of light is inversely proportional to the square root of the product of permeability and permittivity.

4 Easy

4 of 18

Remembering +4 | -1

The S.I. unit of displacement current is:

View answer and explanation

Correct option: C

Ampere

Option C (Ampere) is correct because displacement current, like conventional current, is measured in Amperes, representing the flow of charge per unit time.

5 Easy

5 of 18

Understanding +4 | -1

Given below are two statements:
Statement I: Electromagnetic waves carry energy
as they travel through space and this energy is
equally shared by the electric and magnetic fields
Statement II: When electromagnetic waves strike
a surface, a pressure is exerted on the surface
In the light of the above statements, choose the
most appropriate answer from the options given
below

View answer and explanation

Correct option: A

Both Statement I and Statement II are correct

Option A is correct because electromagnetic waves transport energy through space, and this energy is equally distributed between the electric and magnetic fields. Also, EMW exerts pressure.

6 Easy

6 of 18

Remembering +4 | -1

The range of frequency allotted for FM radio is

View answer and explanation

Correct option: B

88

108 \mathrm{~MHz}

Option B (

88

108 \mathrm{~MHz}

) is correct because it represents the standard frequency range allocated for FM radio broadcasting.

7 Easy

7 of 18

Application +4 | -1

A new system of units is evolved in which the values of

{\mu _0}

and

{\varepsilon _0}

are 2 and 8 respectively. Then the speed of light in this system will be

View answer and explanation

Correct option: A

0.25

Option A (0.25) is correct because the speed of light is inversely proportional to the square root of the product of permeability and permittivity.

8 Easy

8 of 18

Understanding +4 | -1

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

View answer and explanation

Correct option: C

They originate from charges moving with uniform speed

Option C is correct because electromagnetic waves originate from accelerating charges, not charges moving with uniform speed.

9 Easy

9 of 18

Application +4 | -1

A plane electromagnetic wave of frequency

35 {MHz}

travels in free space along the

X

-direction. At a particular point (in space and time)

\vec{E}=9.6 \hat{j} {~V} / {m}

. The value of magnetic field at this point is :

View answer and explanation

Correct option: D

3.2 \times 10^{-8} \hat{k}\, T

Option D (

3.2 \times 10^{-8} \hat{k}\, T

) is correct because the magnetic field is calculated using the relation E = cB, and the direction is determined by the cross product of the wave's propagation direction and the electric field direction.

10 Easy

10 of 18

Understanding +4 | -1

In the case of a photon :-

View answer and explanation

Correct option: D

Its speed can change but cannot become equal to zero.

Option D (Its speed can change but cannot become equal to zero) is correct because a photon always travels at the speed of light in a given medium, but its speed changes when entering a different medium.

11 Easy

11 of 18

Analyzing +4 | -1

A proton moving with a constant velocity passes through a region of space without any change in its velocity. If

\vec{E}

and

\vec{B}

represent the electric and magnetic fields respectively, then the region of space may have:

(A)

E=0, B=0

(B)

E=0, B \neq 0

(C)

E \neq 0, B=0

(D)

E \neq 0, B \neq 0

Choose the most appropriate answer from the options given below:

View answer and explanation

Correct option: C

(A), (B) and (D) only

Option C is correct. A proton can pass through a region with no change in velocity if E=0, B=0; E=0, B� 0 (if velocity is parallel to B); or E� 0, B� 0 (if electric and magnetic forces cancel each other).

12 Easy

12 of 18

Application +4 | -1

An electromagnetic wave has electric field given by

\vec{E}=(9.6 \hat{j}) \sin \left[2 \pi\left\{30 \times 10^6 t-\frac{1}{10} x\right\}\right], x

and

t

are in SI units. The maximum magnetic field is

View answer and explanation

Correct option: A

3.2 \times 10^{-9}

Option A (

3.2 \times 10^{-9}

) is incorrect. The correct answer is

3.2 \times 10^{-8}

because the maximum magnetic field is found using

B = \frac{E}{c}

13 Easy

13 of 18

Remembering +4 | -1

Part of electromagnetic spectrum that has largest penetrating power is

View answer and explanation

Correct option: A

\gamma

-rays

Option A (

\gamma

-rays) is correct because gamma rays have the highest energy and therefore the greatest penetrating power in the electromagnetic spectrum.

14 Easy

14 of 18

Remembering +4 | -1

Rays in electromagnetic spectrum that has lowest frequency are

View answer and explanation

Correct option: A

Microwaves

Option A (Microwaves) is correct because microwaves have the lowest frequency among the given options in the electromagnetic spectrum.

15 Easy

15 of 18

Application +4 | -1

A plane electromagnetic wave travels in a medium of relative permittivity 2 and relative permeability

8.0.

If the magnitude of magnetic intensity is

\frac{6}{\pi} \times 10^{-2} \mathrm{~A} / \mathrm{m}

at a point, then the electric field at that point in ___

\mathrm{V} / \mathrm{m}

View answer and explanation

Correct option: A

1.80

Option A (16) is correct because it is derived from the conversion of units of power from the new system to the standard SI system (watts).

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16 Easy

16 of 18

Remembering +4 | -1

Part of electromagnetic spectrum that corresponds to wavelength of

10^{-10}

m is

View answer and explanation

Correct option: D

X-rays

Option D (X-rays) is correct because X-rays have wavelengths in the range of approximately

10^{-10}

17 Easy

17 of 18

Application +4 | -1

In a plane EM wave, the electric field oscillates sinusoidally at a frequency of

5 \times 10^{10} \mathrm{~Hz}

and an amplitude of

50 \mathrm{Vm}^{-1}

. The total average energy density of the electromagnetic field of the wave is : [Use

\varepsilon_0=8.85 \times 10^{-12} \mathrm{C}^2 / \mathrm{Nm}^2

]

View answer and explanation

Correct option: C

1.106 \times 10^{-8} \mathrm{Jm}^{-3}

Option C (

1.106 \times 10^{-8} \mathrm{Jm}^{-3}

) is correct because the total average energy density of an electromagnetic wave is given by

u = \frac{1}{2} \epsilon_0 E^2

, where E is the amplitude of the electric field.

18 Easy

18 of 18

Understanding +4 | -1

A plane electromagnetic wave propagating along z-direction can be generated by

View answer and explanation

Correct option: B

E_y, B_x

Option B (

E_y, B_x

) is correct because in an electromagnetic wave, the electric and magnetic fields are perpendicular to each other and to the direction of propagation.

Revision notes and key takeaways

Review ELECTROMAGNETIC WAVES in your textbook or class notes, then use this set to check your understanding.

Key Takeaways

✓ This set contains 18 single-correct-answer MCQs on ELECTROMAGNETIC WAVES.
✓ Try each question before opening its answer. Read the explanation where one is available.
✓ Sign in to save submitted answers. Revisit incorrect answers alongside your textbook or class notes.

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