Is there any rule governing the angle light is refracted through?

The first 200 words of this essay...

Is there any rule governing the angle light is refracted through?

Aim: To find a connection or rule governing that angle light is refracted through.

Introduction: Visible light is s form of energy that we can detect with our eyes. Light moves in waves.

The light that we can see has a wavelength of about 1/2000 of a millimetre. The speed of light in air is 300 million metres per second. This is about a million times faster than the speed of sound.

Light travels more slowly in glass than it does in air. It goes about two-thirds as fast through glass than it does in air. This is the reason why light is refracted. Since the light is being slowed down by the optically more dense medium, the ray of light travelling from the air into the glass will bend towards the normal. As below:

A number called the refractive index measures how quickly light travels through a certain material. To work this out you would need this following equation:

Refractive Index of a substance = Speed of light in air

Speed of light in the substance

The refractive