Question

Initially, two thin lenses were kept in contact. Now, if they are separated by d distance, what happens to the focal length of a combination ?

Answer 1

Initially, two thin lenses were kept in contact.

Now, if they are separated by d distance, the following things happen to the focal length of a combination.

The possible combinations are given below.

The power of these two thin lenses is the reciprocal of a focal length in meters.

When it comes to the powers, they are additive.