When a spherical mirror is held towards the sun and its sharp image is formed on a piece of carbon paper for some time, a hole is burnt in the carbon paper.
(a) What is the nature of spherical mirror ?
(b) Why is a hole brnt in the carbon paper ?
( c) At which point of the spherical mirror the carbon paper is placed ?
(d) What name is given to the distance between spherical mirror and carbon paper ? ( e) What is the advantage of using a carbon paper rather then a white paper ?

Answer

(a) Concave mirro (b) A lot of sum's heat rays are concentrated at the point of sun's image which burn the hole in carbon paper ( c) At the focus (d) Fjocal length ( e) A black carbon paper absorbs more heat rays and hence burns a hole more easily (than a white paper).