Question

object of height 4 cm is placed at a distance of 30 cm from the optical centre of a convex lens of focal length 20cm draw a ray diagram to find the position and size of the image formed mark optical Centre O and principal focus f on a diagram also find the approximate ratio of size of the image to size of the object

Answer 1

U will get v= 60 cm
Now
M= hi/ho= -v/u
hi/4=-60/-30
hi= 8cm.
Hope it is clear.

Answer 2

u=60 ,v=30
so u/v=60/30=2