Light Waves

Reflection

Light ray strikes plane (eg. Mirror) and returns to originating source.

Law of reflection

Angle of incidence=angle of reflection

Refraction

Light ray strikes plane and passes through the medium, altering ray speed

Normal

Line perpendicular to surface

Direction of refracted light in a denser medium

Towards the normal

Direction of refracted light in a less dense medium

Away from the normal

Total internal reflection (TIR)

When a refracted ray should be bigger than 90° it is reflected inside the more dense medium following the law of reflection

Critical angle

The minimum angle at which internal reflection takes place- happens when ray changes from just refracting to TIR

Uses of total internal reflection

Endoscope

Optical fibre broadband internet

Decorative fibre lights

Equation linking critical angle and ref reactive index

n=1/sinC