Two professors are stranded on a deserted island. Both wear glasses, though one is nearsighted and the other is farsighted.
(a) Which person's glasses should be used to focus the rays of the Sun and start a fire?
(b) Choose the best explanation from among the following:
I. A nearsighted person can focus close, so that person's glasses should be used to focus the sunlight on a piece of moss at a distance of a couple inches.
II. A farsighted person can't focus close, so the glasses to correct that person's vision are converging. A converging lens is what you need to concentrate the rays of the Sun.