A lens is placed between a source of light and a wall. It forms images of area $A_{1}$ and $A_{2}$ o

Question

A lens is placed between a source of light and a wall. It forms images of area $A_{1}$ and $A_{2}$ on the wall, for its two different positions. The area of the source of light is\

Professor PC Thomas Classes · Answer

(c) : By displacement method, size of object $$ (O)=\sqrt{I_{1} 	imes I_{2}} . $$ Therefore area of source of light $(A)=\sqrt{A_{1} A_{2}}$.\