Question

During the propagation of electromagnetic waves in a medium:

• A. Electric energy density is equal to the magnetic energy density
• B. Both electric and magnetic energy densities are zero
• C. Electric energy density is double of the magnetic energy density
• D. Electric energy density is half of the magnetic energy density

Answer 1

The correct option is A Electric energy density is equal to the magnetic energy density

During the propagation of electromagnetic waves in a medium:
Electric energy density $U_E=\frac{1}{2}ϵE^2$.
Now using $B=\frac{E}{c}$ and $c=\frac{1}{\sqrt{ϵ\mu }}$, we get
$U_E=\frac{1}{2}ϵE^2=\frac{1}{2}\frac{B^2}{\mu }=U_B$.
Electric energy density is equal to the magnetic energy density.