Question

An object of height 5 cm is placed at 30 cm distance on the principal axis in front of a concave mirror of focal length 20 cm. Find the image distance and size of the image.

Answer 1

Object distance (u) = – 30 cm, Focal length (f) = – 20 cm, 

Height of object (h_o) = 5 cm, Image distance (v) = ?, Height of image (h_i) = ?

Mirror formula : 

∴ Image distance is 60 cm from the mirror.

Magnification (m) = -(v/u) = -(-60)/-30 = -2

Again m = h_i /h_o  ⇒ -2 = h_i /5 ⇒ h_i = -10 cm

∴ The image is real ,inverted with a height of 10 cm.