Answer to Question #306310 in Physics for Phil

Question

An object is 3 inches in front of a concave mirror with radius of curvature 12 inches.

Find: a) the image distance.

b) the magnification.

c) the image description: real of virtual? erect of inverted?

Answer 1

Given:

$d_o=3\:\rm in$

$f=R/2=6\:\rm in$

The mirror equation says

$$\frac{1}{d_0}+\frac{1}{d_i}=\frac{1}{f}$$

Hence:

a) the image distance

$$d_i=\frac{fd_o}{d_o-f}=\frac{6*3}{3-6}=-6\:\rm in$$

b) the magnification

$$m=-\frac{d_i}{d_0}=2$$

c) virtual, upright.