Electromagnetic Spectrum

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Electromagnetic radiation travels as waves and transfers energy from one place to another. All electromagnetic waves can travel through a vacuum, and they all travel at the same speed in a vacuum.

The electromagnetic spectrum is a continuous range of wavelengths. The types of radiation that occur in different parts of the spectrum have different uses and dangers, which depend on their wavelength and frequency.

What is a spectrum?

The visible spectrum

White light can be split up using a prism to form a spectrum. A prism is a block of glass with a triangular cross-section. The light waves are refracted as they enter and leave the prism. The shorter the wavelength of the light, the more it is refracted. As a result, red light is refracted the least and violet light is refracted the most, causing the coloured light to spread out to form a spectrum

The electromagnetic spectrum

Visible light is just one type of electromagnetic radiation. There are various types of electromagnetic radiation, some with longer wavelengths than visible light and some with shorter wavelengths than visible light.


Gamma radiation

Gamma waves have a very high frequency. Gamma radiation cannot be seen or felt. It mostly passes through skin and soft tissue, but some of it is absorbed by cells.

Gamma radiation is used, among other things, for the following purposes.

  • to sterilise surgical instruments
  • to kill harmful bacteria in food
  • to kill cancer cells (note that lower doses of gamma radiation could lead to cells becoming cancerous)


X-rays have a lower frequency than gamma radiation. Like gamma rays, they cannot be seen or felt. X-rays mostly pass through skin and…




really good way to remember the EM spectrum

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