In an electromagnetic wave, the amplitude of electric field is 10V/m. The frequency of waves is `5 xx 10^(14) Hz.` The wave is propagating along the Z-axis, then the average density of electric field is

Options

A. `2.21 xx 10^(-10)Jm^(-3)`
B. `3.25 xx 10^(-9)Jm^(-9)`
C. `8.81 xx 10^(-12)Jm^(-3)`
D. `6.25 xx 10^(-3)Jm^(-1)`

Answer

A

Explanation

Here, `E_(0)=10 Vm^(-1), v=5 xx 10^(14)Hz`
The average density due to electric field
`U_(E)=1/2 epsi_(0) E_("rms")^2=1/2 epsi_(0) [E_(0)/sqrt2]^2 =2.21 xx 10^(-10) Jm^(-3)`