A camper is trying to start a fire by focusing sunlight onto a piece of paper. The diameter of the sun is 1.39 × 109 m, and its mean distance from the earth is 1.50 × 1011 m. The camper is using a converging lens whose focal length is 10.0 cm.
(a) What is the area of the sun's image on the paper?
(b) If 0.530 W of sunlight passes through the lens, what is the intensity of the sunlight at the paper?