Question

The outside mirror on the passenger side of a car is convex and has a focal of -7.0 meters. Relative to this mirror, a truck traveling in the rear has an object distance of 11 meters. Find (a) the image distance of the truck and (b) the magnification of the mirror.

Answer 1

(a) The lens equation is 

1/d_o + 1/d_i = 1/f 

Thus, 1/11 + 1/d_i = 1/−7

⇒ d_i = −4.2778

(b) The magnification can be derived from 

m = − d_i/d_o 

thus, m = −−4.2778/-11 = 0.38889