Total energy density of electromagnetic waves in vacuum is given by the relation:
Answer & explanation
Correct answer: option 4
The energy in EM waves is divided equally between the electric and magnetic fields.
The total energy per unit volume is u = ue + um
$=\frac{1}{2} \varepsilon_0 E^2+\frac{1}{2} \frac{B^2}{\mu_0}$