I'm studying for a test that is going to cover mirrors and lenses. I was under the impression that the focal length for any concave or convex mirror was half the radius of curvature:(adsbygoogle = window.adsbygoogle || []).push({});

f=r/2

but one of the questions in my book involving a convex mirror uses a different value for f, according to the solutions manuel. It says that:

f=2/r

of all the questions i've encountered while studying for this test, f has always been r/2. can someone help explain why f can be 2/r?

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Mirror reflection question

**Physics Forums | Science Articles, Homework Help, Discussion**