A wave can transfer energy but not matter Continuous wave has vibrating item at its source. Pulse is caused by single input of energy. Longitudinal wave involve particles of the medium vibrating parallel to the direction of travel of the energy. Transverse wave – the particle vibrates perpendicular to the direction of travel of the energy itself. 1D waves – transverse or longitudinal waves traveling along a rope or string. 2D waves – a ripple in waters surface or earthquakes.3D waves – sound / speaking or a bomb blast that travels outward in all directions. Medium: a substance carrying a wave. Violet light is slowed down most and has greatest refraction angle. Red is slowed least and refracted least. Energy must be present at source of wave.

Short wavelength = high freq (and vice versa) Critical angle = sin ^-1 ( n2/n1) or sin^1(v1/v2) Polarised light is light waves that have their electric fields aligned with each other. Blue sky |Sunlight reaches Earth's atmosphere and is scattered in all directions by all the gases and particles in the air. Blue light is scattered in all directions more than any other colour because it travels as shorter, smaller waves. (Shorter wavelength)