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

Options

A. `6.37 xx 10^(-9) J m^(-3)`
B. `81.35 xx 10^(-12) J m^(-3)`
C. `3.5 xx 10^(-3) J m^(-3)`
D. `4.58 xx 10^(-6) J m^(-3)`

Answer

D

Explanation

Averge energy density,
`mu_(av) = (1)/(2)epsi_(0)E_(0)^(2)`
`= 1/2 epsi_(0)(sqrt(2)E_(rms))^(2) = epsi_(0)E_(rms)^(2)`
`= 8.85 xx 10^(-12) xx (720)^(2)`
`= 4.58 xx 10^(-6) Jm^(-3)`