Question

Why paper catches fire when a convex lens is used to focus sunlight?​

Answer 1

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 Increases, Combustion Will Occur When The Spot Becomes Too Hot & The Paper Burns. ❤

Answer 2

Answer:

A convex lens focuses sun light at a point on the paper. The photons in the sun light have energy. These are concentrated at one point and a lot of heat is generated. As there is combustible material (paper), oxygen ( in the air) and the heat energy raises the temperature at the focal point to over the flash point for paper, a fire starts.