The ratio of contributions made by the electric field and magnetic field components to the intensity of an EM wave is a) c: 1 b) c2 : 1 c) 1: 1 d) √c: 1
Correct option is C) The intensity of an electromagnetic wave is given by: I=Uavc here, Uav is the average energy and c is the speed of light. The average energy in terms of the electric field is written as: Uav=21εoEo2 Average energy in terms of magnetic field: Uav=21μoBo2 We know that, Eo=cBo and c=μoεo1 ∴Uav (electric field)=21εo×μoεo1Bo2 ⇒21μoBo2 Since the energy due to electric and magnetic field is same. so, both will have the same contribution to the intensity.
