Question

A plane electromagnetic wave of frequency $25 \,MHz$ travels in free space along the $x$-direction. At a particular point in space and time, $E=6.3 \hat{j} \,V / m$. At this point $B$ is equal to

• A. $8.33 \times 10^{-8}\,\hat{ k} T$
• B. $18.9 \times 10^{-8}\,\hat{ k} T$
• C. $2.1 \times 10^{-8} \,\hat{k }T$
• D. $2.1 \times 10^{8} \,\hat{k} T$

Answer 1

Answer: (C)

$ c=\frac{E}{B} $
Magnetic field, $ B=\frac{E}{c} $
$ =\frac{6.3}{3\times 10^{8}} $
$ = 2.1\times 10^{-8} $