a man looks at himself in a magnifying concave bathroom mirror whose focal length is 20cm. His face is 10cm from the mirror. At what distance from his face is the image? What is its magnification?

Question

matt101 · Answer

You can figure this out using the mirror equation:

$${1 \over f}={1 \over o}+{1 \over i}$$
Where f is the focal length, o is the object distance, and i is the image distance. First calculate the value of i. Then find the difference between o and i for your answer. Keep in mind that for a concave mirror, f is positive.

The equation for magnification is:
$$m=-{i \over o}$$
Just use the values for o and i you have from the last question!