Question

Why a paper held in sunshine at focus of a convex lens burns?​

Answer 1

convex lens is also know as converging lens when a beam of light fall on a convex lens it converges all the light rays at a single point. this makes the paper to burn

Answer 2

Answer:

convex lens concentrates the light energy to one spot on the paper so that the heat energy accumulates on that one small spot of paper As the heat incrases combustion will occurs when the spot becomes too hot and paper burns