Question

If the electric field and magnetic field of an electromagnetic wave are related as $B=\frac{E}{c}$ where the symbols have their usual meanings and the energy in a given volume of space due to the electric field part is $U$, then the energy due to the magnetic field part will be

• A. $\frac{U}{c}$
• B. $\frac{U}{n^2}$
• C. $\frac{U}{2}$
• D. $U$

Answer 1

Answer: (D)

$B=\frac{E}{C}$
Energy due to $E=\frac{1}{2}{\epsilon }_0{E}^2$
Energy due to $B=\frac{B_0{}^2}{2{\mu }_0}$
$E_{\text{part }}=\frac{U}{2}$
$B_{\text{part }}=\frac{U}{2}$
$E_{\text{part }}=B_{\text{part }}$