Refraction

Reflection & Refraction

Refraction

Air – lower refractive index

Water – higher refractive index

The Kingfisher•When light is passing from a higher refractive substance into a lower refractive substance the light rays bend away from the perpendicular to the surface.

perpendicular

Refraction

Air – lower refractive index

Water – higher refractive index

The Fish•When light is passing from a lower refractive substance into a higher refractive substance the light rays bend toward the perpendicular to the surface.

perpendicular

Refraction

Air – lower refractive index

Glass – higher refractive index

Glass Window

Air – lower refractive index

Refraction

•Light passing through a transparent material exits at the same angle it enters

Lens

ApplicationRefraction

Total Internal ReflectionTotal Internal Reflection

• Can occur when light inside glass block hits the edge at

certain angles

• As you increase the angle the ray gets bent

• However – at a particular angle called the Critical Angle

something strange happens

TOTAL INTERNAL REFLECTION OF LIGHT

NINCIDENT RAY

REFRACTED RAY

The ray is refracted parallel to the edge of the block at the

Critical angle

As we increase the angle of As we increase the angle of incidenceincidence

• As the angle of incidence increases, the ray is now only reflected back inside the block

• The edge of the block acts like a mirror• The ray does not pass out of the block• This is total internal reflection

So the 600 angle has total internal reflection

Internal ReflectionInternal Reflection• This occurs only when light travels from

more dense to less dense media.

AppplicationsAppplications• Fibre optics

– Communication– Lighting– Endoscopy