Write the relation between critical angle and refractive index of a medium.

Explanation

To derive the relation between the critical angle (θc) and the refractive index (ν) of a medium, we can follow these steps:

### Step 1: Understanding Total Internal Reflection (TIR)
Total Internal Reflection occurs when light travels from a denser medium to a rarer medium. The critical angle is the angle of incidence in the denser medium at which the angle of refraction in the rarer medium becomes 90 degrees.

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