Q.

A point source of 100 W emits light with 5% efficiency. At a distance of 5 m from the source, the intensity produced by the electric field component is            [2023]

1 12πWm2  
2 140πWm2      
3 110πWm2  
4 120πWm2  

Ans.

(2)

IEF=12×54π×52=140πW/m2