Question

An object 3 cm high is placed at a distance of 10 cm in front of converging mirror of focal length 20 cm Find the position ,nature and size of image formed

Answer 1

Given; height of object, h1 = 3 cm, u = -20 (the mirror is converging, i.e. convex), f = 20 cm

1/f = 1/v + 1/u

1/20= 1/v + 1/-20

1/20 = 1/v - 1/20

1/v= 1/20+ 1/20

1/v = 2/20 =1/10

v = + 10 cm

Nature= The image formed is virtual and erect (it is formed behind the mirror) because v is positive.

Position= The position of image is 10 cm behind the mirror.

m=-v/u

= -10/-20

=1/2

m = 0.5 cm

m = h2/h1

0.5 = h2/3

h2 = 0.5 × 3

h2 = 1.5 cm

Size= The size of image is 1.5 cm