An electromagnetic wave of frequency `1xx10^(14)` Hertz is propagating along z-axis. The amplitude of electric field is `4V//m`. If `epsilon_(0)=8.8xx10^(-12)C^(2)//N-m^(2)`, then average energy density of electric field will be:

Options

A. `35.2xx10^(-10)J//m^(3)`
B. `35.2xx10^(-11)J//m^(3)`
C. `35.2xx10^(-12)J//m^(3)`
D. `35.2xx10^(-13)J//m^(3)`

Answer

C

Explanation

Given : Amplitude of electric field,
`E_(0)=4v//m`
Absolute permitivity,
`epsilon_(0)=8.8xx10^(-12)c^(2)//N-m^(2)`
Average energy density `u_(E)=?`
Applying formula,
Average energy density `u_(E)=(1)/(4)epsilon_(0)E^(2)`
`rArr" "u_(E)=(1)/(4)xx8.8xx10^(-12)xx(4)^(2)`
`=35.2xx10^(-12)J//m^(3)`