A point source emitting 628 lumen of luminous flux uniformly in all directions is placed at the origin. Calculate the illuminance on a sall area placed at (1.0 m, 0, 0) in such a way that the mnormal to the area makes an angle of `37^@` with the X-axis.

Answer

D

Explanation

l=luminous intensity `=628/(4pi)=50 candela`
`r=1m, theta=37^@`
so ilumiN/Ance `e=costheta/r^2`
`=50xx(cos37^0)/1^2`
`=50x(4/5)/1=40lux`