A point object is placed at a distance of `20 cm` from a thin plano-concex lens of focal length `15 cm`. The plane surface of the lens is now silvered. The image created by the is at :

Options

A. `A. 60 cm` to the left of the system.
B. `B. 60 cm` to the right of the system.
C. `C. 12 cm` to the left of the system.
D. `D. 12 cm` to the right of the system.

Answer

C

Explanation

By mirror-lens combination formula
`(1)/(F)=(1)/(f_(m))-(1)/(f_(L))`
`(1)/(F)=(1)/(infty)-(2)/(15)`
By mirror formula
`(1)/(F)=(1)/(u)+(1)/(v) rArr -(2)/(15)=(1)/(-20)+(1)/(v)`
`rArr (1)/(v)=(1)/(20)-(2)/(15)=(3-8)/(60)`
`v=-12 cm` negartive means toward left