You are asked to design a shaving mirror assuming that a person keeps it `10cm` from his face and views the magnified image of the face at the closest comfortable distance of `25cm`. The radius of curvature of the mirror would then be:

Options

A. 30 cm
B. 24 cm
C. 60 cm
D. 22 cm

Answer

C

Explanation

For the image to form at 25 cm from the observer.s eye, the image distance from the mirror should be 15 cm and the image will be formed beyond the mirror.

`u=-10cm" "v=+15cm`
Mirror formula
`(1)/(u)+(1)/(v)=(1)/(f)`
`(1)/((-10))+(1)/(15)=(1)/(f)`
`(-5)/(150)=(1)/(f)`
`rArr" "f=-30cm`
Radius of curvature `=R=2f=2xx30cm = 60cm`