A wave is a transfer of energy and information.
The vibration of a transverse wave is perpendicular to the direction of which it is travelling (the wave moves up and down while the direction of the wave is PERPENDICULAR). For example, electromagnetic waves (can move through a vaccuum; e.g. light waves) are transverse as the waves' direction is perpendicular to the way it is vibrating.
The vibrations of a longitudinal wave is made up of compressions (when the waves are close together) and rarefractions (when the waves are spread apart). For example, mechanical waves (can travel through a medium; e.g. sound waves and waves on springs) are longitudinal or transverse because they compress, rarefracture and move perpendicular to the way it is vibrating.
As seen in this diagram, the wavelength can be measured in 3 different ways. The amplitude is the height to the position of rest and the frequency is the number of wave crests passing a point in 1 second (measured in hertz; Hz). A speed of a wave (measured in wavespeed; m/s) is measured by multiplying frequency (Hz) by wavelength (m).
A virtual image is sometimes seen due to a reflection. There are two rays of light in a reflection and that is an incidence ray and a reflected ray. The normal is an imaginary line perpendicular to the mirror's or glass' surface. The angle between the incidence ray and the normal is called the angle of …