Question

1. Which of the following can produce infinite magnification?
(a) convex mirrors and convex lenses
(b) convex mirrors and concave lenses
(c) concave mirrors and concanve lenses
(d) concave mirrors and convex lenses
(e) None. Magnification never approaches infinity

Answer 1

The equation for magnification is:

m = hi/ho = -di/do

Convex lenses can produce real images if the object is placed outside the focal point or virtual images if the object is

inside the focal point. Concave lenses always produce virtual images. With lenses the object distance, do, is positive

if the object is in front of the lens and negative if it is in back of the lens. The image distance, di , is positive if the

image is in back of the lens and negative if it is in front of the lens. In other words, if the rays from the object pass

through the lens and converge, the object and image will be on opposite sides of the lens, do and di will have the

same sign, and the image will be real. If the rays from the object diverge, the object and image will be on the same

side of the lens, do and di will have opposite signs, and the image will be virtual.

Ans :- (e) None. Magnification never approaches infinity