Question

An object is placed at (i) 10 cm, (ii) 5 cm in front of a concave mirror of radius of curvature 15 cm. Find the position, nature, and magnification of the image in each case.

Answer 1

The focal length f = –15/2 cm = –7.5 cm 

(i) The object distance u = –10 cm. Then Eq. (1) gives 

The image is 30 cm from the mirror on the same side as the object. Also, magnification m = -u/v = - (-30/-10) = -3. The image is magnified, real and inverted. 

(ii) The object distance u = –5 cm. Then from Eq. (1),

This image is formed at 15 cm behind the mirror. It is a virtual image. 

Magnification m = - (v/u) = - (15/-5) = 3. The image is magnified, virtual and erect.