In a plane electromagnetic wave, the electric field oscillates sinusoidally at a frequency of `2.0xx10^(10) Hz` and amplitude 48 V `m^(-1)`.

Explanation

Here, v=`2.0xx10^(10) Hz, E_(0)=48 Vm^(-1),C=3xx10^(8) m//s`
For average energy density
`U_(E)=1/2 epsi_(0)E_(0)^(2)………………. (1)`
We known that `(E_(0))/(B_(0))=C`
Putting in Eq (1)
`U_(E)=(1)/(4)epsi_(0).C^(2)B_(0)^(2)..............(2)`
Speed of Electro magnetic waves, `C=(1)/(sqrt(mu_(0)E_(0)))`
Putting in Eq (2) We get .
`U_(E)=(1)/(4) epsi_(0) B_(0)^(2)* (1)/(mu_(0)epsi_(0))`
`U_(E)=1/4 * (B_(o)^(2))/(mu_(0))=(Bo^(2))/(2mu_(0))=mu_(B)`
Thus, the average energy density of E field equals the average energy density of B field.