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 10 8 m/s), in glass its speed falls to 200,000,000 m/s (2 x 10 8 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 90 o ? Glass block Air

AQUINAS DIOCESAN GRAMMAR O I O Real depthApparent depth

AQUINAS DIOCESAN GRAMMAR

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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.