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JEE • PHYSICS • ELECTROMAGNETIC WAVES

Electromagnetic waves practice · Medium

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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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Showing 1-30 of 226 questions
1 Medium
1 of 226
Understanding +4 | -1
Statement I: Sound waves are not electromagnetic waves.

Statement II: Sound waves require a material medium for propagation.
View answer and explanation
Correct option: A
Statement I and statement II are true
Option A (Statement I and statement II are true) is correct because sound waves are mechanical waves (not electromagnetic) and require a medium to propagate.
2 Medium
2 of 226
Application +4 | -1
For a plane electromagnetic wave propagating in x-direction, which one of the following combination gives the correct possible directions for electric field (E)(E) and magnetic field (B)(B) respectively?
View answer and explanation
Correct option: D
−j^+k^,−j^−k^- \widehat j + \widehat k, - \widehat j - \widehat k
Option D (−j^+k^,−j^−k^\widehat{-j} + \widehat{k}, \widehat{-j} - \widehat{k}) is correct because the cross product of the electric and magnetic field vectors results in a vector along the x-direction, which is the direction of propagation.
3 Medium
3 of 226
Analyzing +4 | -1
Assertion: The relative velocity of two photons travelling in opposite directions is the velocity of light.

Reason: The rest mass of photon is zero
View answer and explanation
Correct option: B
If both assertion and reason are true, but reason is not correct explanation of the assertion.
Option B is correct because while both the assertion and reason are true, the zero rest mass of a photon doesn't explain why their relative velocity is c.
4 Medium
4 of 226
Understanding +4 | -1
Intensity of electromagnetic wave will be
View answer and explanation
Correct option: B
I=cε0 B02/2\mathrm{I}=\mathrm{c} \varepsilon_0 \mathrm{~B}_0^2 / 2
Option A (I=cμ0 B02/2\mathrm{I}=\mathrm{c} \mu_0 \mathrm{~B}_0^2 / 2) is incorrect. Option C (I=B02/cμ0\mathrm{I}=\mathrm{B}_0^2 / \mathrm{c} \mu_0) is incorrect. Option D (I=E02/2cε0\mathrm{I}=\mathrm{E}_0^2 / 2 \mathrm{c} \varepsilon_0) is incorrect. Option B (I=cε0 B02/2\mathrm{I}=\mathrm{c} \varepsilon_0 \mathrm{~B}_0^2 / 2) is correct because it represents the average intensity of an electromagnetic wave in terms of the speed of light, permittivity, and magnetic field amplitude.
5 Medium
5 of 226
Application +4 | -1
The rms value of the electric field of the light coming from the Sun is 720  N/C720\;N/C. The average total energy density of the electromagnetic wave is
View answer and explanation
Correct option: D
4.58×10−6  J/m34.58 \times {10^{ - 6}}\;J/{m^3}
Option D (4.58×10−6  J/m34.58 \times {10^{ - 6}}\;J/{m^3}) is correct because the average total energy density is calculated using the formula vAV=ε0Erms2{v_{AV}} = {\varepsilon _0}E_{rms}^2.
6 Medium
6 of 226
Understanding +4 | -1
Methane is a greenhouse gas because
View answer and explanation
Correct option: A
It absorbs longer wavelengths of the electromagnetic spectrum while transmitting shorter wavelengths
Option A (It absorbs longer wavelengths of the electromagnetic spectrum while transmitting shorter wavelengths) is correct because greenhouse gases trap heat by absorbing infrared radiation.
7 Medium
7 of 226
Remembering +4 | -1
The correct expression in accordance with Gauss’s law for magnetism is
View answer and explanation
Correct option: B
∮B⃗⋅ds=0\oint \vec{B} \cdot d s=0
Option B (∮B⃗⋅ds=0\oint \vec{B} \cdot d s=0) is correct because Gauss's law for magnetism states that the net magnetic flux through any closed surface is zero.
8 Medium
8 of 226
Remembering +4 | -1
If μ0{\mu _0} is permeability of free space and ε0{\varepsilon _0} is permittivity of free space, the speed of light in vacuum is given by
View answer and explanation
Correct option: C
1μ0ε0\sqrt {\frac{1}{{{\mu _0}{\varepsilon _0}}}}
Option C (1μ0ε0\sqrt {\frac{1}{{{\mu _0}{\varepsilon _0}}}}) is correct because the speed of light in vacuum is given by c=1μ0ε0c = \frac{1}{\sqrt{{\mu_0 \varepsilon_0}}}.
9 Medium
9 of 226
Application +4 | -1
In a plane electromagnetic wave, the electric field varies with time having an amplitude 1 Vm−11 \mathrm{~Vm}^{-1}. The frequency of wave is 0.5×1015 Hz0.5 \times 10^{15} \mathrm{~Hz}. The wave is propagating along zz-axis. What is the average amplitude of magnetic field?
View answer and explanation
Correct option: A
3.33×10−9 T3.33 \times 10^{-9} \mathrm{~T}
Option A (3.33×10−9 T3.33 \times 10^{-9} \mathrm{~T}) is correct because it is calculated using the relationship between the electric field amplitude and the magnetic field amplitude in an electromagnetic wave, B0=E0/cB_0 = E_0/c.
10 Medium
10 of 226
Remembering +4 | -1
The range of wavelength of the visible light is
View answer and explanation
Correct option: B
4000A∘  to  8000  A∘  4000\mathop \mathrm{A}\limits^ \circ \;to\;8000\;\mathop \mathrm{A}\limits^ \circ \;
Option B is correct because the range of wavelengths for visible light is approximately 4000 Å to 8000 Å.
11 Medium
11 of 226
Understanding +4 | -1
In an electromagnetic wave, if Eˉ\bar{E} and Bˉ\bar{B} represent electric and magnetic field respectively, then
View answer and explanation
Correct option: A
Eˉ\bar{E} and Bˉ\bar{B} oscillate in same phase
Option A is correct because in an electromagnetic wave, the electric and magnetic fields oscillate in the same phase and are perpendicular to each other.
12 Medium
12 of 226
Understanding +4 | -1
Out of the following options which one can be used to produce a propagating electromagnetic wave?
View answer and explanation
Correct option: D
An accelerating charge
Option D (An accelerating charge) is correct because accelerating charges produce electromagnetic waves.
13 Medium
13 of 226
Understanding +4 | -1
Which of the following is not electromagnetic in nature
View answer and explanation
Correct option: C
Cathode rays
Option C is correct because cathode rays are streams of electrons, which are particles, not electromagnetic radiation.
14 Medium
14 of 226
Understanding +4 | -1
Which of the following has/have zero average value in a plane electromagnetic wave
View answer and explanation
Correct option: A
Both magnetic and electric fields
Option A is correct because in a plane electromagnetic wave, both the electric and magnetic fields oscillate sinusoidally, and their average values over a complete cycle are zero.
15 Medium
15 of 226
Understanding +4 | -1
Which one of the following is not electromagnetic in nature
View answer and explanation
Correct option: C
Cathode rays
Option C is correct because cathode rays are streams of electrons, which are particles, while X-rays, Gamma rays, and Infrared rays are electromagnetic waves.

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16 Medium
16 of 226
Application +4 | -1
The wavelength of the oscillatory magnetic field in a plane electromagnetic wave given by By=0.6×10−5sin⁡(4000πx−5×1010πt)TB_y=0.6 \times 10^{-5} \sin \left(4000 \pi x-5 \times 10^{10} \pi t\right) T is (where xx is meter and tt is in second)
View answer and explanation
Correct option: C
0.5××10−3 m0.5 \times \times 10^{-3} \mathrm{~m}
Option C (0.5×10−3 m0.5 \times 10^{-3} \mathrm{~m}) is correct because the wavelength is calculated from the wave number in the given equation of the magnetic field.
17 Medium
17 of 226
Remembering +4 | -1
Which of the following waves have the maximum wavelength
View answer and explanation
Correct option: D
Radio  wavesRadio\;waves
Option D (Radio  wavesRadio\;waves) is correct because radio waves have the longest wavelength compared to X-rays, I.R. rays, and UV rays.
18 Medium
18 of 226
Remembering +4 | -1
Solar radiation is an example of
View answer and explanation
Correct option: A
Transverse electromagnetic wave
Option A (Transverse electromagnetic wave) is correct because solar radiation consists of electromagnetic waves, which are transverse in nature, meaning the electric and magnetic fields oscillate perpendicular to the direction of propagation.
19 Medium
19 of 226
Understanding +4 | -1
Which of the following are true?
A. Speed of light in vacuum is dependent on the direction of propagation.
B. Speed of light in a medium is independent of the wavelength of light.
C. The speed of light is independent of the motion of the source.
D. The speed of light in a medium is independent of intensity.
Choose the correct answer from the options given below:
View answer and explanation
Correct option: A
C and D only
Option A (C and D only) is correct because the speed of light is independent of the motion of the source and the intensity of light.
20 Medium
20 of 226
Understanding +4 | -1
In the propagation of electromagnetic waves, the angle between the direction of propagation and plane of polarisation is
View answer and explanation
Correct option: A
0∘0^{\circ}
Option A is correct because the direction of propagation is along the electric field vector in the plane of polarization, hence the angle is 0 degrees.
21 Medium
21 of 226
Remembering +4 | -1
All components of the electromagnetic spectrum in vacuum have the same
View answer and explanation
Correct option: B
Velocity
Option B (Velocity) is correct because all electromagnetic waves travel at the speed of light in a vacuum.
22 Medium
22 of 226
Understanding +4 | -1
Statement I: Displacement current arises on account of change in electric flux.

Statement II: Conduction current arises due to the flow of electrons through the connecting wires of a circuit in a closed path
View answer and explanation
Correct option: A
Statement I and statement II are true
Option A (Statement I and statement II are true) is correct because both statements accurately describe displacement and conduction currents.
23 Medium
23 of 226
Understanding +4 | -1
X-rays, gamma rays and microwaves travelling in vacuum have
View answer and explanation
Correct option: C
Same speed but different wavelength
Option B (same speed but different wavelength) is correct because X-rays, gamma rays, and radio waves all travel at the speed of light in a vacuum but have different wavelengths.
24 Medium
24 of 226
Remembering +4 | -1
Microwave oven acts on the principle of :
View answer and explanation
Correct option: C
giving vibrational energy to water molecules
Option C (giving vibrational energy to water molecules) is correct because microwaves cause water molecules to vibrate, generating heat.
25 Medium
25 of 226
Application +4 | -1
Using B=μ0HB=\mu_0 H find the ratio E0/H0E_0 / H_0 for a plane electromagnetic wave propagating through vacuum. Show that it has the dimensions of electric resistance. This ratio is a universal constant called the impedance of free space.
View answer and explanation
Correct option: A
377 Ω377 \, \Omega
Option A (377 Ω377 \, \Omega) is correct because it is the calculated value of the impedance of free space, derived from the ratio of electric field to magnetic field in vacuum.
26 Medium
26 of 226
Remembering +4 | -1
Which of the following radiations has the least wavelength
View answer and explanation
Correct option: A
γ−rays\gamma - rays
Option A (γ−rays\gamma - rays) is correct because gamma rays have the shortest wavelength and highest frequency in the electromagnetic spectrum.
27 Medium
27 of 226
Analyzing +4 | -1
Assertion: The microwaves are better carriers of signals than radio waves.

Reason: The electromagnetic waves do not require any medium for propagation.
View answer and explanation
Correct option: B
If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion
The correct answer is B because both the assertion and reason are true, but the reason does not explain the assertion. Microwaves are better signal carriers due to their higher frequency, and EM waves don't need a medium.
28 Medium
28 of 226
Understanding +4 | -1
Assertion: EM wave follow superposition principle.

Reason : Differential expression of EM wave islinear.
View answer and explanation
Correct option: A
If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion
Option A (If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion) is correct because EM waves follow the superposition principle due to the linearity of their differential expression.
29 Medium
29 of 226
Understanding +4 | -1
Radio wave diffract around building although light waves do not. The reason is that radio waves
View answer and explanation
Correct option: B
Have much larger wavelength than light
Option B (Have much larger wavelength than light) is correct because diffraction is more pronounced when the wavelength of the wave is comparable to or larger than the size of the obstacle.
30 Medium
30 of 226
Remembering +4 | -1
Which of the following electromagnetic waves has minimum frequency?
View answer and explanation
Correct option: B
Audible waves
Option B (Audible waves) is correct because audible waves are mechanical waves, not electromagnetic waves, and generally have lower frequencies than radio waves.
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 226 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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