The critical angle of incidence in a glass slab placed in air is `45^@`. What will be be the critical angle when the glass slab is immersed in water of refractive index `1.33` ?

Explanation

To find the critical angle when a glass slab is immersed in water, we can follow these steps:

### Step 1: Understand the concept of critical angle
The critical angle is the angle of incidence above which total internal reflection occurs when light travels from a denser medium to a rarer medium. The critical angle (C) can be calculated using Snell's law.

### Step 2: Use Snell's Law
Snell's law states that:
\[
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