Intext Question.
Take two convex lenses of different sizes. Collect sunlight on a paper using one of the lenses. The paper will start burning after a while. Note the time required for the paper to start burning. Repeat the process for the second lens. Is the time required the same in both cases? What can you tell from this?

Explanation

No. Both the lenses will take different time to bum the paper. We can conclude that the capacity of a lens to converge the incident light is different for different lens and it depends on the size of the lens.