Question

Convex and concave mirrors have the same radius of curvature R. Distance between the mirrors is 2R. At what point on common optical axis of the mirrors of the mirrors should a point source of light A be placed for the rays to converge at a point A after being reflected first on the convex and then on the concave mirror?

Answer 1

Answer:

You will need to measure the distance from the vertex to the focal point. But first you must find the focal point. The trick involves focusing light from a distant source (the sun is ideal) upon a sheet of paper. Once you find the focal point, make your focal length measurement.