An object is placed between a plane mirror and a concave mirror of focal length 15 cm as shown in Figure . Find the position of the images after two reflections.

Explanation

a. If reflection is first taken on the plane mirror:
For second reflection at the concave mirror:
`u=-40cm, f=-15cm`
`(1)/(v)+(1)/(-40)=-(1)/(15)rArrv=-24cm`
b. If reflection is first taken on the concave mirror:
`u=-20cm`
`(1)/(v)+(1)/(-20)=-(1)/(15) rArr v=-60cm`
Finally image will be formed at the pole of concave mirror.