10.(c) In a plane electromagnetic wave, the electric field oscillates sinusoidally at a frequency of and amplitude .
Show that the average energy density of the E field equals the average energy density of the B field.
The average energy density of the Electric field(UE)
=
= (as E=Bc)
=
=UB
Therefore the average energy density of the electric field is equal to the average energy density of the Magnetic field.