In a movie hall the distance between the projector and the screen is increased by $1 \%$. The illumi

Question

In a movie hall the distance between the projector and the screen is increased by $1 \%$. The illumination on the screen is\

Professor PC Thomas Classes · Answer

$I=\frac{L}{d^{2}}$. When d increases by 1% I decreases by $2 	imes 1 \%$.\