Question

An object is put at a distance of 5cm from the first focus of a convex lens of focal length 10cm. If a real image is formed, its distance from the lens will be
A. 15cm
B. 20cm
C. 25cm
D. 30cm

Answer 1

Correct Answer - d.
`(1)/(v)-(1)/(u)=-(1)/(f)`
`(1)/(v)-(1)/(-15)=(1)/(f)`
or `(1)/(v)-(1)/(15)=(1)/(10)` or `(1)/(v)=(-2+3)/(30)`
or `v=30cm`