The real image of an object is located 35.0 cm away from a concave mirror,which has a focal length of 10.0 cm.How far is the object from the mirror?
A) 40.0 cm
B) 35.0 cm
C) 14.0 cm
D) 12.9 cm

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, we can rearrange to solve for do. 
1/do = 1/f - 1/di 
1/do = 1/10 - 1/35 
do = 14 cm 
Therefore, the object is located 14 cm away from the mirror, so the answer is C.

The Real Image of an Object Is Located 35