Question

A plane electromagnetic wave of frequency $25MHz$ travels in free space along $x$-direction. At a particular point in space and time, electric field $E=6.3V{m}^{-1}$, the magnitude of magnetic field B at this point is:

• A. $1.2\times {10}^{-6}T$
• B. $1.2\times {10}^{-8}T$
• C. $2.1\times {10}^{-6}T$
• D. $2.1\times {10}^{-8}T$

Answer 1

The correct option is D $2.1\times {10}^{-8}T$

Given that, $\overrightarrow{E}=6.3V{m}^{-1}$

Velocity of electromagnetic wave $V=3\times {10}^8$

As, er know that

$B=\frac{E}{c}$

$⟹B=\frac{6.3}{3\times {10}^8}=2.1\times {10}^{-8}T$