Question

An object is placed at a distance of 25 cmfrom a spherical mirror and its image is formed behind the mirror at the distance of 5 cm.Find the focal length of mirror.Name the type of mirror and one of its uses.

Answer 1

Object distance,u=-25cm
Image distance,v= +5 cm
For a mirror,we know that,
1/f=1/v+1/u
=1/(5) +1/(-25)
f =(-25)(5) / (-25+5)
f = 25/4
f = 6.25cm
This will be a convex mirror(focus is positive ).