Question

In an electromagnetic wave in free space the root mean square value of the electric filed is $E_{rms}=6V/m$. The peak value of the magnetic field is:

• A. $4.23\times {10}^{-8}T$
• B. $1.41\times {10}^{-8}T$
• C. $2.83\times {10}^{-8}T$
• D. $0.70\times {10}^{-8}T$

Answer 1

Answer: (C)

$2.83\times {10}^{-8}T$

$E_{rms}=6V/m$
$E_{rms}=E_{rms}\times \sqrt{2}=6\sqrt{2}V/m$
Now, $E=CB$
$\to B=\frac{E}{C}=\frac{6\sqrt{2}}{3\times {10}^8}$
$=2.25\times {10}^{-8}T$
$=2.828\times {10}^{-8}T$