Question

an object is place at 30cm in front of concave mirror of focal length 15cm. at what distance from the mirror would a screen be placed in order to obtain a sharp image?

Answer 1

Hey there!!

We have ,

Object distance , u = -30

focal length = 15 cm

$\frac{1}{v} = \frac{1}{f} - \frac{1}{u} \\ \\ = \frac{ - 1}{15} + \frac{1}{30} \\ \\ = > \frac{ - 2 + 1}{30} \\ = > v \: = - 30 \: cm$
Hence at a distance of -30 cm image will form sharp and clean

Hope this helps u !!!

Answer 2

Object distance =-30
Focal length=-15

Object distance is twice the focal length

This in the case of concave mirror is the centre of curvature.

This implies the mirror should be at 30 cm