A biconvex lens of focal length 15 cm is in front of a plane mirror. The distance between the lens and the mirror is 10 cm. A small object is kept at a distance of 30 cm from the lens. The final image is

Options

A. Virtual and at a distance of `16 cm` from mirror
B. Real and at distance of `16 cm` from the mirror
C. Virtual and at a distance of `20 cm` from the mirror
D. Real and at a distance of `20 cm` from the mirror

Answer

B

Explanation

First image,
`(1)/(v)-(1)/(u)=(1)/(f)`
`(1)/(v)-(1)/(-30)=(1)/(15)`
`v=30` , iamge in formed `20 cm` behind the mirror.
Second image, by plane mirror will be at `20 cm` infront of plane mirror.

For third image `(1)/(v)-(1)/(10)=(1)/(15)`
`(1)/(v)=(1)/(10)+(1)/(15)=(3+2)/(30)=(5)/(30)`
`v=6 cm`