Question

The ratio of amplitude of magnetic field to the amplitude of electric field of an electromagnetic wave propagating in vacuum is

• A. Reciprocal of speed of light in vacuum
• B. The speed of light in vacuum
• C. Proportional to frequency of the electromagnetic wave
• D. Inversely proportional to the frequency of the electromagnetic wave

Hint:

The ratio of the electric field to the magnetic field in an electromagnetic wave is constant and is equal to the speed of light. The reciprocal of this ratio gives the answer for this question.

Answer 1

The Correct Option is A

The relationship between the amplitude of the magnetic field (B₀) and the amplitude of the electric field (E₀) in an electromagnetic wave propagating in vacuum can be described by the equation:

BE=1c

Where,

• B: Amplitude of the magnetic field
• E: Amplitude of the electric field
• c: Speed of light in vacuum (approximately 3×108m/s)

This shows that the ratio of the amplitude of the magnetic field to the amplitude of the electric field in an electromagnetic wave is the reciprocal of the speed of light. 

Therefore, the correct option is: Reciprocal of speed of light in vacuum

Answer 2

For an electromagnetic wave propagating in vacuum, the relationship between the electric field \( E \) and magnetic field \( B \) is given by: \[ \frac{E}{B} = c \] where:
- \( E \) is the electric field,
- \( B \) is the magnetic field,
- \( c \) is the speed of light in vacuum.
Thus, the ratio of the amplitude of the magnetic field to the amplitude of the electric field is: \[ \frac{B}{E} = \frac{1}{c} \] Therefore, the correct answer is the reciprocal of the speed of light in vacuum.