Where should an object be placed from a converging lens of focal length 20 cm, so as to obtain a real image of magnification 2?

Options

A. 50 cm
B. 30 cm
C. -50 cm
D. -30 cm

Answer

D

Explanation

For real image from converging lens,
`m = -2`
`therefore` Magnification, `m =(f)/(f+u)rArr -2=(f)/(u+f)=(20)/(u+20)`
`rArr " " u=-30 cm`