Reflection and Refraction

Reflection

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Reflection involves a change in direction of waves when they bounce off a barrier.

When light hits a mirror it bounces off the mirror. This is  reflection. The ray of light hitting the mirror is known as the incident ray and the ray of light bouncing off is called the reflected ray. 

The angle of incidence is always the same size as the angle of reflection.

Also, The angles are always measured from the ray to the normal line. The normal line is a line at right angles to the mirror.

The image is always the same distance behind the mirror as the object is in front and the image is always the same size as the object and it is laterally inverted (left becomes right)

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Refraction

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Refraction of waves involves a change in the direction of the waves when they pass from one medium to another, this is because different materials have different densities.. 

Refraction, or the bending of the path of the waves, is also accompanied by a change in the speed and the wavelength of the waves. All wave types can be refracted.

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Ray diagrams show the refraction of a wave at a boundary. 

Refraction can cause optical illusions as the light waves appear to come from a different position to their actual source.