A concave lens (n = 1.5 ) is immersed in water ( n = 1.33 ). Now the lens will become

1. less convergent

2. more convergent

3. less divergent

4. more divergent

The focal length of a lens depends on the refractive index of the medium of the lens.

The change in focal length can be found by the formula,

Where, n is the refractive index of the material of the lens (n_lens) with respect to the refractive index of the medium (n_medium).

So, when immersed in water n decreases and hence focal length of the lens increases.

Here, n = 1.5/1.33 = 1.13 > 1

So, the lens will still be converging but its focal length will increase. Thus, it becomes less convergent.