Regions of the EM Spectrum

Regions of the EM Spectrum

The Electromagnetic Spectrum

Introduction to the EM Spectrum

  • The electromagnetic (EM) spectrum refers to the full range of all types of electromagnetic radiation.
  • Electromagnetic radiation is made up of photons – these are bundles of energy that travel in waves.
  • The different types of electromagnetic radiation are categorised by their wavelength. The shorter the wavelength, the higher the energy of the photons.

Radio Waves

  • Radio waves have the longest wavelengths in the EM spectrum.
  • They carry signals for television and radio. Even longer wavelengths carry data between satellites and the Earth.
  • Radio waves produce low energy and are non-ionising.


  • Microwaves have slightly shorter wavelengths.
  • They carry signals for mobile phones and are used to heat food in microwave ovens.
  • Like radio waves, microwaves are non-ionising and can cause tissues to heat up.

Infrared Waves

  • Infrared waves have shorter wavelengths than microwaves.
  • Infrared is responsible for the heat we feel from the Sun, a fire or a radiator.
  • They are used in heat sensors and thermal imaging cameras.

Visible Light

  • Visible light spectrum lies in the middle of the EM spectrum.
  • This is the only part of the spectrum we can perceive with our eyes.
  • It’s emitted by the Sun and also by anything hot enough to glow.

Ultraviolet Radiation

  • Ultraviolet (UV) radiation has a shorter wavelength than visible light.
  • It’s responsible for causing sunburns, but it’s also what our bodies need to produce vitamin D.
  • High-energy UV can cause damage to cells, which can lead to skin cancer.


  • X-rays are further along the spectrum with an even shorter wavelength.
  • They can pass through body tissue which makes them useful in medical imaging.
  • X-rays are high energy and can cause ionisation, which can lead to mutations and cancer.

Gamma Rays

  • Gamma rays have the shortest wavelength of the EM spectrum.
  • They are produced by nuclear reactions, such as those in the Sun or nuclear power plants.
  • Gamma rays are highly energetic and can cause cancer and other damage to living tissues.

Understanding the properties of each region of the EM spectrum allows us to harness these waves for modern technologies ranging from telecommunication systems to medical devices.