Question

A 20 cm tall object is placed in front of a concave mirror with a radius of 31 cm. The distance of the object to the mirror is 94 cm. Calculate the focal length of the mirror.

Answer 1

The focal length of the concave mirror is -15.5 cm

Step-by-step explanation:

Given that,

Height of the object, h = 20 cm

Radius of curvature of the mirror, R = -31 cm (direction is opposite)

Object distance, u = -94 cm

We need to find the focal length of the mirror. The relation between the focal length and the radius of curvature of the mirror is as follows :

R = 2f

f is the focal length

`f=(R)/(2)`

`f=(-31)/(2)`

f = -15.5 cm

So, the focal length of the concave mirror is -15.5 cm. Hence, this is the required solution.