Critical Angle and TIF

```Q1. Define the term
‘refractive index’
Q2. α = 45o , β = 32o
Calculate the
refractive index
angle of refraction when the angle of
incident is; a) 30o b) 80o c) 0o
Q4. What happens to the period of the
wave when it gets refracted?
Medium
Air
Water (liquid)
Water (ice)
Vegetable Oil
Silica (quartz)
Human Cornea
Flint Glass
Diamond
Glycerol
Absolute
Refractive Index
1.00
1.33
1.31
1.46
1.46
1.38
1.65
2.42
1.47
n1 , n2 , n3 , … = absolute refractive index
1n2
= relative refractive index where:
n2
n

1 2
n1
Example:
If light travels from water to diamond, what
would be the relative refractive index?
Try this!
Refractive index of water = 1.33
Refractive index of air = 1.00
Light travels from water into air
Angle of incidence = 75o
Angle of refraction = ???
Critical Angle
The angle of incidence where light
entering an optically less dense medium
refracts at right angles
Total Internal Reflection
Where light is totally reflected instead
of being refracted. Occurs when the
angle of incidence is greater than the
critical angle.
```