A concave spherical mirror has a focal length of 12 cm.If an object is placed 6 cm in front of it the image position is:
A)4 cm behind the mirror
B)4 cm in front of the mirror
C)12 cm behind the mirror
D)12 cm in front of the mirror
E)at infinity

Question

Quizplus · Accepted Answer

Using the mirror formula, 1/f = 1/do + 1/di where f is the focal length, do is the object distance, and di is the image distance.
Plugging in the values given:
1/12 = 1/6 + 1/di
Simplifying:
1/di = 1/12 - 1/6 = -1/12
Solving for di:
di = -12 cm
The negative sign shows that the image is formed behind the mirror. Therefore, the correct answer is C) 12 cm behind the mirror.

A Concave Spherical Mirror Has a Focal Length of 12