Question

Prove that the ratio of magnetic energy density and electric energy density is unity.

Answer 1

In an electromagnetic wave

$E=\sqrt{\dfrac{​μ_o}{\epsilon_o}}​​ ​H$ ..................(1)

Magnetic Field energy density :

$η_B=\dfrac{H^2}{2μ_o}$

Electric Field energy density :

$η_E=\dfrac{E^2ϵ_o}{2}$

Substituting the value of E in the in the η_E we get $η_E=η_B$