Question

Between which two points of concave mirror should an object be placed to obtain a magnification of:

(a) −3
(b) +25
(c) −0.4

Answer 1

(a) An object, in front of a concave mirror, should be placed between the latter's centre of curvature (C) and focus (F) to obtain a magnification of −3.
(b) An object, in front of a concave mirror, should be placed between the latter's focus (F) and the pole (P) to obtain a magnification of +25. 
(c) An object, in front of a concave mirror, should be placed beyond the latter's centre of curvature (C) to obtain a magnification of −0.4.