EM waves and the electromagnetic spectrum

Electromagnetic (EM) waves are transverse waves. Their vibrations or oscillations are changes in electrical and magnetic fields at right angles to the direction of wave travel.

All electromagnetic waves:

  • transfer energy as radiation from the source of the waves to an absorber
  • can travel through a vacuum such as in space
  • travel at the same speed through a vacuum or the air

Electromagnetic waves travel at 300,000,000 metres per second (m/s) through a vacuum.

Electromagnetic spectrum

Electromagnetic waves form a continuous spectrum of waves. This includes:

  • waves with a very short wavelength, high frequency and high energy
  • waves with a very long wavelength, low frequency and low energy

Electromagnetic waves can be separated into seven distinct groups in the spectrum.

All known forms of waves from radio waves to gamma raysThe electromagnetic spectrum

Often a phrase is used to help remember the order of the groups of the electromagnetic spectrum such as Roman Men Invented Very Unusual X-ray Guns.

Each group contains a range of frequencies. For example, visible light contains the limited range of frequencies that can be detected by the human eye:

  • red light has the lowest frequencies of visible light
  • violet light has the highest frequencies of visible light