Question

A plane EM wave of frequency $25~\text{MHz}$ propagates in vacuum. If electric field is $6.3~\text{V/m}$, then magnitude of magnetic field is

• A. $2.1 \times 10^{-8}~\text{T}$
• B. $4.2 \times 10^{-8}~\text{T}$
• C. $6.3 \times 10^{-8}~\text{T}$
• D. $8.4 \times 10^{-8}~\text{T}$

Hint:

In EM waves, $B = \dfrac{E}{c}$ with $c = 3 \times 10^8~\text{m/s}$.

Answer 1

The Correct Option is A

$B = \dfrac{E}{c} = \dfrac{6.3}{3 \times 10^8} = 2.1 \times 10^{-8}~\text{T}$