Question

A plane electromagnetic wave of frequency $50MHz$ travels in free space along the positive x-direction. At a particular point in space and time, $\overrightarrow{E}=6.3\hat{j}V/m$. The corresponding magnetic field $\overrightarrow{B}$, at that point will be:

• A. $18.9\times {10}^{-8}\hat{k}T$
• B. $6.3\times {10}^{-8}\hat{k}T$
• C. $2.1\times {10}^{-8}\hat{k}T$
• D. $18.9\times {10}^8\hat{k}T$

Answer 1

The correct option is C $2.1\times {10}^{-8}\hat{k}T$

$|B|=\frac{|E|}{[C}=\frac{6.3}{3\times {10}^8}=2.1\times {10}^{-8}T$
and $\hat{E}\times \hat{B}=\hat{C}$
$\hat{j}\times B=\hat{i}$
$\hat{B}=\hat{k}$
$\overrightarrow{B}=|B|\hat{B}=2.1\times {10}^{-8}\hat{k}T$