In an electromagnetic wave, the amplitude of electric firld is `1 V/m`. The frequency of wave is `5xx10^(14)Hz`. The wave is propagating along `z`-axis. The average energy density of electric field, in `"joule"//m^(3)`,will be

Options

A. `1.1 xx 10^(-11)`
B. `2.2 xx 10^(12)`
C. `3.3 xx 10^(-13)`
D. `4.4 xx 10^(-14)`

Answer

B

Explanation

Average energy density= `(1)/(2)epsilon_(0)E^(2)= (1)/(2)epsilon_(0)((E_(0))/(sqrt(2)))^(2)= (1)/(4)epsilon_(0)E_(0)^(2)= (1)/(4) xx 8.85 xx 10^(-12) xx (1)^(2)= 2.2 xx 10^(-12) J//m^(3)`