Question

An object is placed on the principle axis of a convex lens of focal length 10 cm. If the distance of the object from the lens is 30

Answer 1

hope it's hlp ;
Thank you :-)

Answer 2

Lens formula1/f=1/v-1/u

Given u=-30 cm.and f=10cm. Now1/v=1/f+1/u;1/v=1/10-1/30

We get v=15cm.

Here we use negative sign for object distance u according to sign convention. Please go through rules of sign convention.