A candle is 55.0 cm in front of a convex spherical mirror of radius of curvature 56.0 cm.What are the image distance and the magnification,respectively?

Question

Quizplus · Accepted Answer

Using the mirror equation: 
1/f = 1/do + 1/di 
Where f is the focal length (equals to half of the radius of curvature for a spherical mirror), do is the object distance, and di is the image distance. 
Rearranging the equation: 
1/di = 1/f - 1/do 
1/di = 1/28 - 1/55 
di = -18.6 cm 
The negative sign indicates that the image is virtual and upright. 
To find the magnification: 
m = -di/do 
m = -(-18.6)/55 
m = 0.337 
The positive magnification indicates that the image is upright. 
Therefore, the correct answer is A) -18.6 cm, +0.337.

A Candle Is 55