AQUINAS DIOCESAN GRAMMAR

Refraction of Light

AQUINAS DIOCESAN GRAMMAR

The bending of light is called refraction.

Refraction happens when light travels from one material (e.g. air) into a different material (e.g. glass or water).

AQUINAS DIOCESAN GRAMMAR

Incident ray

normal

refracted ray

normal

Glass block

Air

i

r

i = angle of incident

r = angle of refraction

AQUINAS DIOCESAN GRAMMAR

Light travels more slowly in glass than in air

In air (and a vacuum) light travels at 300,000,000 m/s (3 x 108 m/s), in glass its speed falls to 200,000,000 m/s (2 x 108 m/s).

Light is refracted because its speed changes when it enters another medium.

Demo

AQUINAS DIOCESAN GRAMMAR

The angle between the ray entering the block and the normal is called the angle of incidence (i).

The angle between the ray inside the block and the normal is called the angle of refraction (r).

normal

Glass block

Air

i

r

AQUINAS DIOCESAN GRAMMAR

Laws of Refraction

When a ray of light passes from an optically less dense medium to an optically more dense medium, at an angle, the ray is refracted towards the normal.

normal

Glass block

Air

i

r

normal

Glass block

Air

When a ray of light passes from an optically more dense medium to an optically less dense medium, at an angle, the ray is refracted away from the normal.

AQUINAS DIOCESAN GRAMMAR

What do you think will happen to a ray of light striking an air-glass boundary at 90o?

Glass block

Air

AQUINAS DIOCESAN GRAMMAR

O

I

O

Real depth Apparent depth

AQUINAS DIOCESAN GRAMMAR

AQUINAS DIOCESAN GRAMMAR

AQUINAS DIOCESAN GRAMMAR

Red Richard

Orange of

Yellow York

Green Gave

Blue Battle

Indigo In

Violet Vain

AQUINAS DIOCESAN GRAMMAR

AQUINAS DIOCESAN GRAMMAR

The light enters your eye through the transparent cornea, passes through the lens and is focused on the retina.

The retina is sensitive to light and sends messages to your brain by way of the optic nerve.

The iris changes in size to vary the amount of light that enters through the pupil.