Question

A point light source is kept in front of a convex mirror at a distance of 40 cm. The focal length of the mirror is 40 cm. Find the position of image. 

Answer 1

Given,

u = 40 cm (negative)

f = 40 cm (positive)

Mirror formula:

`1/u + 1/v = 1/f`

Substituting the values in the formula above, we get,

`- 1/40 + 1/v = 1/40`

`1/v = 1/40 + 1/40`

`1/v = (1 + 1)/40`

`1/v = 2/40`

`1/v = 1/20`

⇒ v = 20 cm.

The image is behind the mirror at a distance 20 cm.