An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focused image can be obtained? Find the size and the nature of the image.

u = – 27 cm, f = – 18 cm. h0 = 7.0 cm 1/v = 1/f- 1/u 1/v = -1/18 + 1/27 = -1/54 V = – 54 cm Screen must be placed at a distance of 54 cm from the mirror in front of it. hi/h0= v/u hi/h0= v/u hi/7 = +54/-27 hi= -2 x 7 = -14 cm. Thus, the image is of 14 cm length and is inverted image