Question

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

Answer 1

Correct Answer - D
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`