Practicing Success
In an electromagnetic wave, the amplitude of electric field is 1 V/m. The frequency of wave is 5 × 10–14 Hz. The wave is propagating along z-axis. The average energy density of electric field, in Joule/m3, will be: |
1.1 × 10–11 2.2 × 10–12 3.3 × 10–13 4.4 × 10–14 |
2.2 × 10–12 |
Average energy density is given by $U_{E}=\frac{1}{2} \varepsilon_0 E^2=\frac{1}{2} \varepsilon_0\left(\frac{E_0}{\sqrt{2}}\right)^2=\frac{1}{4} \varepsilon_0 E_0^2$ $=\frac{1}{4} \times 0.85 \times 10^{-12} \times(1)^2$ = 2.2 × 10–12 J/m3 |