1. A lens can be characterized by its power, which
(a) Is the same as the magnification?
(b) Tells how much light the lens can focus.
(c) Depends on where the object is located.
(d) Is the reciprocal of the focal length.
2. You cover half of a lens that is forming an image on a screen. Compare what happens when you cover the top half of the lens versus the bottom half.
(a) When you cover the top half of the lens, the top half of the image disappears; when you cover the bottom half of the lens, the bottom half of the image disappears.
(b) When you cover the top half of the lens, the bottom half of the image disappears; when you cover the bottom half of the lens, the top half of the image disappears.
(c) The image becomes half as bright in both cases.
(d) Nothing happens in either case.
(e) The image disappears in both cases.