Light energy

Crest

Highest point of a wave

Trough

Lowest point of a wave

Amplitude

Maximum displacement from central position of wave

Wavelength

Length of a wave

Frequency

How often waves are completed in a certain amount of time

Period

The time it takes for a wave to pass a point

Reflection

When light bounces off an object

Law of reflection

Angle of incidence is equal to angle of reflection

Angle of incidence

Angle between incident ray and normal

Angle of reflection

Angle between reflected ray and normal

Ray diagram

A diagram that shows how light travels

Refraction

When light changes speed and direction as it enters a medium with different density

Medium

A material that a wave travels through

Normal

An imaginary perpendicular line to the surface

Refractive index

The index that influences the speed of light in the material

Angle of refraction

The angle between refracted ray and normal

Convex lens

Lens thicker in the centre and converges light ray

Concave lens

Lens thinner in the middle and diverges light rays

Electromagnetic spectrum

Full range of waves