What happens to focal length of a convex lens when it is immersed in water ?

Explanation

To determine what happens to the focal length of a convex lens when it is immersed in water, we can follow these steps:

### Step 1: Understand the Lens Formula
The lens formula is given by:
\[ \frac{1}{f} = (n - 1) \left( \frac{1}{r_1} - \frac{1}{r_2} \right) \]
where:
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