A camper is trying to start a fire by focusing sunlight onto a piece of paper. The diameter of the sun is 1.39x109 m, and its mean distance from the earth is 1.50x1011 m. The camper is using a converging lens whose focal length is 10.1cm.
(a) Determine is the area of the sun's image on the paper?
(b) If 0.728 W of sunlight pass through the lens, what is the intensity of the sunlight at the paper?