Geometrical optics Definition and 52 Threads

Hi Could someone point me to websites with tutorials on the real-virtual sign convention for geometric optics (and possibly other known conventions too)? I've been googling for some time but the results aren't too satisfying. PS--Tutorials with mathematics are preferred... Thanks and...

I just have a few questions on geometrical optics. 1. Why do the hands of a clock move counterclockwise in a mirror? 2. If you move farther away from a plane mirror, will you be able to see more of yourself or less? 3. How do you decide if the image in a mirror is real or virtual...