Find the behaviour of concave lens placed in a rarrer medium.

Explanation

To find the behavior of a concave lens placed in a rarer medium, we can follow these steps:

### Step 1: Understand the Lens Maker's Formula
The lens maker's formula is given by:

\[ \frac{1}{f} = \left( \frac{\mu_l}{\mu_m} - 1 \right) \left( \frac{1}{R_1} - \frac{1}{R_2} \right) \]
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