Question

For a convex lens object is placed at a distance 7.5 it's image is found at10cm from the lens the focal length of the lens will be

Answer 1

Answer:

4.2cm

Explanation:

Given: u=-7.5cm v=10cm

As it is a convex lens, 1/v-1/u=1/f

1/10-(-1/7 5)=1/10+1/7.5=7.5+10/75=

175/750.

f=750/175 =4.2cm.

Answer 2

Answer:

answer attached in photo