Question

The rms value of the electric field of the light coming from the sun is 720 N/C. The average total energy density of the electromagnetic wave is :

• A. $4.58 \times10^{-6} \,J/m^{3}$
• B. $6.37 \times10^{-9} \,J/m^{3}$
• C. $81.35 \times10^{-12} \,J/m^{3}$
• D. $3.3 \times10^{-3} \,J/m^{3}$

Answer 1

Answer: (A)

Total average energy $=\varepsilon_{0}E^{2}_{rms}$
$=8.85 \times10^{-12} \times\left(720\right)^{2}$
$=4.58\times10^{-6}\,j/m^{3}$