Question

An object is placed first at infinity and then at 20 cm from the object side
focal plane of a convex lens. The two images thus formed are 5 cm apart.
The focal length of the lens is​

Answer 1

Answer:

1/f 1/v-1/u v=infinity u=20 1/20-1/ inf.

f = 20

Answer 2

Answer:

Explanation:

Pls check the attachment.