# What will happen to the focal length of convex lens which is placed inside water ?

##### 1 Answer

Feb 2, 2017

I would think that it gets bigger.

#### Explanation:

We know from the famous Lensmaker´s Formula that:

where:

Consider an exampe:

A lens that has a focal length of

In air:

In water:

substitute one into the other for

rearranging: