## June 2, 2011

### 3.22 Critical angle and refractive index

Recall and use the relationship between critical angle and refractive index:

$\textup{sin}\, c = \frac{1}{n}$

c is the critical angle (in degrees,°)
n is Refractive index (no units)

Examples:
What is the refractive index of glass that has a critical angle of 42°?

$\textup{sin}\, c = \frac{1}{n}$

What is the critical angle for diamond? (Refractive index of diamond = 2.4)

$\textup{sin}\, c = \frac{1}{n}$

$\textup{sin}^{-1} \left (\frac{1}{2.4} \right ) = c$

$c = 24.6243...$

#### 1 comment:

1. Excellent
First answer should be n=1.5 as you only know c to 2s.f. so answer should be to 2s.f.