An object is held at a distance of 18 cm from a convex mirror creating an image that is 1/6 the object size. What is the focal length of the mirror?
A) "-3.6 cm"
B) "-18 cm"
C) "-6.0 cm"
D) "-9.0 cm"

Question

Quizplus · Accepted Answer

The correct answer is A because the formula for the focal length of a convex mirror is f = -d_i * d_o / (d_i - d_o), where d_i is the distance of the object from the mirror and d_o is the distance of the image from the mirror. In this case, d_i = 18 cm and d_o = 18 cm / 6 = 3 cm, so f = -18 cm * 3 cm / (18 cm - 3 cm) = -6 cm.

An Object Is Held at a Distance of 18 Cm