In an electromagnetic wave, the amplitude of electric field 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. `1.1xx10^(-11)`
B. `2.2xx10^(-12)`
C. `3.3xx10^(13)`
D. `4.4xx10^(-44)`

Answer

B

Explanation

Average energy density of electric field is given by
`u_(e)=(1)/(2)epsilon_(0)E^(2)=(1)/(2)epsilon_(0)((E_(0))/(sqrt(2)))^(2) =(1)/(4)epsilon_(0)E_(0)^(2)`
`=(1)/(4)xx8.85xx10^(-12)(I)^(2)=2.2xx10^(-12)J//m^(3)`