ray of light comes to the interface that is part of a sphere of radius r=15.0 cm. The media are air on the convex, incident side and glass of index of refraction n=1.50 on the other side.
(a) Where does the refracted ray cross the principal axis if the incident ray is 5.0 cm away from the principal axis?
(b) What is the focal length if the interface is treated as a lens?