Draw suitable diagrams to illustrate how a beam of light incident parallel to the principal axis is reflected by :
(a) a concave mirror, and (b) a convex mirror.
How does the action of a convex lens differ from that of a concave lens on a parallel beam of light incident on them ? Draw diagrams to illustrate your answer.
A beam of light incident on a thin concave lens parallel to its principle axis diverges and appears to come from a point F on the principal axis. Name the point F. Draw a ray diagram to show it.