Question

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 focussed image can be obtained? Find the size and the nature of the image.

Answer 1

Objective distance, u = 27 cm

Object height, h = 7 cm

Focal length, f = 30 cm

R = 2f, f = -18 cm

As per mirror formula

Screen should be placed in front of mirror at the distance of = 54 cm

Negative sign of magnification indicates image is real Magnification,

h1 = 7 × (2) = -14 cm

Image is inverted because of negative sign.