# I have a question about a concave mirror where the focal point is on the outside.

1. Mar 19, 2009

### afcwestwarrior

I know that when the focal point is in the inside of a concave mirror. The focal point is greater than zero, and the radius is greater than zero and the lateral magnification is greater than zero.

So if the focal point is on the outside of this concave mirror. Would the focal point be less than zero, and would the radius be less than zero, and would the lateral magnification be less than zero.

2. Mar 19, 2009

### mgb_phys

Sorry not sure what you mean, the focal length of a concave mirror is half the radius of curvature.

see http://www.glenbrook.k12.il.us/GBSSCI/PHYS/class/refln/u13l3a.html [Broken]

Last edited by a moderator: May 4, 2017