In terms of classical wave theory, a very hot object such as any star or sun produces a range of electromagnetic waves. (E.g. The Sun produces ultraviolet light in addition to visible light) Electromagnetic waves are often collectively referred to as electromagnetic radiation.
Electromagnetic radiation is produced by acceleration or sudden movement of electrons. The electron in motion constitutes the electric current that generates the magnetic field in the wave.
- Electromagnetic waves are transverse waves, consisting of electric and magnetic waves at right angles to each other and perpendicular to the direction of wave propagation.
- Electromagnetic waves can travel through vacuum and do not need a medium to traverse. They can travel through solids, liquids and gases.
- All electromagnetic waves have the same speed in vacuum of 3 x 108 m s-1 (commonly referred to as the ‘speed of light’). But the speed slows down in other material media.