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\times {{10}^{-6}}J/{{m}^{3}} $
• B. $ 6.37\times {{10}^{-9}}J/{{m}^{3}} $
• C. $ 81.35\times {{10}^{-12}}J/{{m}^{3}} $
• D. $ 3.3\times {{10}^{-3}}J/{{m}^{3}} $

Answer 1

Answer: (A)

Total average energy
$ ={{\varepsilon }_{0}}E_{rms}^{2} $
$ =8.85\times {{10}^{-12}}\times {{(720)}^{2}} $
$ 4.58\times {{10}^{-6}}J/{{m}^{3}} $