The amplitude of the magnetic field in a plane electromagnetic wave in vacuum is 2 × 10^-8 T. The amplitude of its electric field is (c = 3 × 10⁸ m/s):

A2 × 10^-8 V/m
B
6 V/m
C6.7 × 10^-17 V/m
D1.5 × 10¹⁶ V/m

Q24. AI-generated practice Single-correct MCQ Medium

In a plane electromagnetic wave travelling in vacuum, the oscillating electric and magnetic fields are:

A
in phase with each other
B
180° out of phase
C
in phase only at the source
D
90° out of phase

Q25. AI-generated practice Single-correct MCQ Medium

At a certain point and instant, the electric field of an electromagnetic wave is along +x and its magnetic field is along +y. The wave is travelling along:

A
−y
B
−z
C
+z
D
+x

Q26. AI-generated practice Single-correct MCQ Hard

An electromagnetic wave travels through a non-magnetic medium of relative permittivity 4. Its speed in the medium is (c = 3 × 10⁸ m/s):

A0.75 × 10⁸ m/s
B1.5 × 10⁸ m/s
C6 × 10⁸ m/s
D3 × 10⁸ m/s

Q27. AI-generated practice Single-correct MCQ Medium

Unlike sound waves, electromagnetic waves:

A
are longitudinal
B
always travel more slowly in vacuum than in air
C
cannot travel through vacuum
D
do not need a material medium to travel

Q28. AI-generated practice Single-correct MCQ Easy

Electromagnetic waves are produced by:

A
accelerated (oscillating) charges
B
charges moving with constant velocity
C
steady currents only
D
charges at rest

Q29. AI-generated practice Single-correct MCQ Medium

The electric field of an electromagnetic wave in vacuum is E = E₀ sin(2π × 10⁸ t − kx). Its wavelength is (c = 3 × 10⁸ m/s):

A
3 m
B
0.33 m
C
6π m
D
30 m

Q30. AI-generated practice Single-correct MCQ Hard

For the wave E = E₀ sin(2π × 10⁸ t − kx) in vacuum, the propagation constant k is about (c = 3 × 10⁸ m/s):

A6.3 × 10⁸ rad/m
B
0.33 rad/m
C
1.05 rad/m
D
2.1 rad/m

Q31. AI-generated practice Single-correct MCQ Medium

A non-magnetic transparent material has relative permittivity 2.25 at optical frequencies. Its refractive index is:

A
0.67
B
5.06
C
1.5
D
2.25

Q32. AI-generated practice Single-correct MCQ Hard

Electromagnetic waves carry:

A
neither energy nor momentum
B
momentum but not energy
C
both energy and momentum
D
energy but not momentum

Q33. AI-generated practice Single-correct MCQ Easy

When light passes from air into glass, which property of the wave remains unchanged?

A
wavelength
B
speed
C
frequency
D
direction (in general)

Q34. AI-generated practice Single-correct MCQ Medium

For a plane electromagnetic wave in vacuum, the ratio of the magnitude of the electric field to that of the magnetic field at any point is equal to:

A
1/c
B
1
Cμ₀ε₀
D
the speed of light c

Q35. AI-generated practice Numerical value Easy

The magnetic field amplitude of an electromagnetic wave in vacuum is 1 × 10^-7 T. Find the amplitude of its electric field in V/m. (c = 3 × 10⁸ m/s)

Q36. AI-generated practice Numerical value Medium

Find the wavelength in metre of an electromagnetic wave of frequency 150 MHz in vacuum. (c = 3 × 10⁸ m/s)

Q37. AI-generated practice Numerical value Medium

An electromagnetic wave travels through a non-magnetic medium of relative permittivity 9. If its speed in the medium is x × 10⁷ m/s, find x. (c = 3 × 10⁸ m/s)

Q38. AI-generated practice Numerical value Hard

The electric field amplitude of an electromagnetic wave in vacuum is 60 V/m. If its magnetic field amplitude is x × 10^-8 T, find x. (c = 3 × 10⁸ m/s)

Q39. AI-generated practice Assertion–Reason Medium

Assertion (A): Electromagnetic waves can travel through vacuum.
Reason (R): They consist of oscillating electric and magnetic fields that sustain each other and need no material medium.

A
Both A and R are true and R is the correct explanation of A
B
Both A and R are true but R is not the correct explanation of A
C
A is true but R is false
D
A is false but R is true

Q40. AI-generated practice Assertion–Reason Hard

Assertion (A): In a plane electromagnetic wave in vacuum, the electric and magnetic fields oscillate in phase with each other.
Reason (R): The electric and magnetic fields of an electromagnetic wave are parallel to each other.

A
Both A and R are true and R is the correct explanation of A
B
Both A and R are true but R is not the correct explanation of A
C
A is true but R is false
D
A is false but R is true