EM Wave Fundamentals MCQs

Practice EM Wave Fundamentals MCQs with four options, answers and explanations for focused Electronics & Telecommunication Engineering revision.

Question 1

Electromagnetic TheoryEM Wave Fundamentals

The approximate speed of an electromagnetic wave in free space is?

A3×10^6 m/s
B3×10^8 m/s
C3×10^10 m/s
D9×10^16 m/s

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Correct Answer: B. 3×10^8 m/s

Explanation: Electromagnetic waves propagate in vacuum at approximately 3×10^8 m/s.

Reference: Standard electromagnetic theory: em wave fundamentals

Question 2

Electromagnetic TheoryEM Wave Fundamentals

A free-space electromagnetic wave has frequency 100 MHz. Its wavelength is approximately?

A0.3 m
B3 m
C30 m
D300 m

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Correct Answer: B. 3 m

Explanation: λ=c/f=(3×10^8)/(100×10^6)=3 m.

Reference: Standard electromagnetic theory: em wave fundamentals

Question 3

Electromagnetic TheoryEM Wave Fundamentals

The intrinsic impedance of free space is approximately?

A50 ohm
B75 ohm
C120 pi ohm
D600 ohm

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Correct Answer: C. 120 pi ohm

Explanation: η0=sqrt(mu0/epsilon0)=120π ohm, approximately 377 ohm.

Reference: Standard electromagnetic theory: em wave fundamentals

Question 4

Electromagnetic TheoryEM Wave Fundamentals

For a uniform plane wave propagating in a lossless medium, the magnitude ratio E/H equals the medium’s?

AIntrinsic impedance
BConductivity
CWavelength
DPropagation constant only

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Correct Answer: A. Intrinsic impedance

Explanation: For a uniform plane wave, |E|/|H|=η, the intrinsic impedance of the medium.

Reference: Standard electromagnetic theory: em wave fundamentals

Question 5

Electromagnetic TheoryEM Wave Fundamentals

In a source-free lossless homogeneous medium, electromagnetic waves are?

ATransverse, with E and H perpendicular to the direction of propagation
BPurely longitudinal with E parallel to propagation
CPurely electrostatic
DUnable to carry energy

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Correct Answer: A. Transverse, with E and H perpendicular to the direction of propagation

Explanation: Uniform plane electromagnetic waves in a source-free isotropic medium have mutually perpendicular E, H and propagation directions.

Reference: Standard electromagnetic theory: em wave fundamentals

Question 6

Electromagnetic TheoryEM Wave Fundamentals

The speed of an electromagnetic wave in a lossless medium of permeability mu and permittivity epsilon is?

A1/sqrt(mu epsilon)
Bsqrt(mu epsilon)
Cmu/epsilon
Depsilon/mu

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Correct Answer: A. 1/sqrt(mu epsilon)

Explanation: The phase velocity in a lossless homogeneous medium is v=1/sqrt(με).

Reference: Standard electromagnetic theory: em wave fundamentals