Question

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

• A. The ratio of magnetic permeability to the electric susceptibility of vacuum
• B. The speed of light in vacuum
• C. Unity
• D. Reciprocal of speed of light in vacuum

Answer 1

The correct option is D Reciprocal of speed of light in vacuum

The amplitude of magnetic field and electric field for an electromagnetic wave propagating in vacuum are related as
$E_0=c{B}_0$
So required ratio, $\frac{B_0}{E_0}=\frac{1}{c}$
Hence, the ratio will be Reciprocal of speed of light $c$ in vacuum.