Question

A 5cm tall object is placed on the principal axis of a convex lens .it's 2cm image is formed on the screen placed at a distance 10cm from the lens . Calculate the focal length of the lens

Answer 1

height of object =5cm
height of image=2cm
u =10cm
m=hi/ho
m=5/2
m=v/u
5/2=v/10
v=25cm