The average value of electric energy density in an electromagnetic wave is (E₀ is peak value)

• A

  $\frac{1}{2}{\mathrm{\epsilon }}_0{\mathrm{E}}_0^2$

• B

  $\frac{{\mathrm{E}}_0^2}{2{\mathrm{\epsilon }}_0}$

• C

  ${\mathrm{\epsilon }}_0{\mathrm{E}}_0^2$

• D

  $\frac{1}{4}{\mathrm{\epsilon }}_0{\mathrm{E}}_0^2$