This point of intersection is the focal point of the mirror. A concave mirror will focus all light parallel to the OA through this point.
Measure the distance from the focal point to the apex. This is the focal length.
How are the focal length and the radius of the curve related? (HINT: measure from C to the apex and compare it to the focal length)


Also notice the symmetry of the reflections. If you were to reverse the reflected and incident rays, then any light passing through f will reflect parallel to the OA.


We will use this kind of symmetry of the concave mirror to develop a set of 4 Easy Rays to help us determine the characteristics of an image formed by any object on the OA.
 
 

Previous   Next