Question

A convex lens of focal length 0.12 m produces a virtual n image which is thrice the size of the object. Find the distance between the object and the lens

• A. 0.04 m
• B. 0.08 m
• C. 0.12 m
• D. 0.24 m

Answer 1

The correct option is B 0.08 m

From lens formula
$\frac{1v-\frac{1}{u}}{=}\frac{1}{f}$
$\frac{u}{v}-1=\frac{u}{f}$
$\frac{u}{v}=\frac{u+f}{f}$
$\frac{v}{u}=\frac{f}{u+f}$
For a convex lens f = 0.12m and m=3 then find u
So , $3=\frac{0.12}{0.12+u}$
$0.36+3u=0.12$
$u=-0.08m$