Electromagnetic spectrum




To find out more about the diagram above . . . . read on!

Electromagnetic spectrum

Look carefully at the diagram at the top of the page. Now check out the following questions (and answers)!

  1. What unit is used to measure the frequency of visible light?
  2. Which type of electromagnetic radiation has the highest frequency?
  3. Do radio waves or gamma rays transport more energy?
  4. Shorter wavelength = higher frequency or lower frequency ?
  5. Lower frequency = longer wavelengths or shorter wavelengths?

About the Diagram

Introducing the diagram! Read back and forward between the image at the top of the page and the explanation below!

This diagram shows that the electromagnetic spectrum includes waves with all possible wavelengths, ranging from low energy radio waves through visible light to high energy gamma rays.

  • Notice that a wave with a longer wavelength has a lower frequency and carries less energy.
  • Notice that a wave with a shorter wavelength has a higher frequency and carries more energy.

Remember that:

  • The electromagnetic spectrum includes, in order of increasing frequency and decreasing wavelength: radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
  • There are no precisely defined boundaries between the bands of electromagnetic radiation in the electromagnetic spectrum. Each band is associated with different properties and applications – think of radios, microwaves, x-ray machines etc.
  • Visible light is only a very small part of the electromagnetic spectrum.
  • Energy (electromagnetic energy) is the radiant energy (light) transported by electromagnetic waves.
  • The term light can be used in three different ways:
    • Light can be used to mean the whole of the electromagnetic spectrum from radio waves, through visible light to gamma rays. A better term is radiant energy or photon energy.
    • Light can be used to mean the range of wavelengths and frequencies that can be detected by the human eye. A better term is visible light which refers to the wavelengths that correspond with the colours between red and violet, the visible spectrum.
    • Light can be used to mean the range of wavelengths and frequencies between infra-red and ultra-violet. This usage is useful because the outer limits of the visible spectrum change under different lighting conditions and for different individuals.
  • Referring to visible light simply as light is short-hand.
  • Visible light is not the same for all living things.

Follow the blue links for definitions . . . . or check the summaries of key terms below!

Some Key Terms

Move to the next level! Check out the following terms.


An electronvolt is a unit of energy commonly used to measure the energy carried by electromagnetic radiation. Electronvolts can be ...
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Energy is a property of matter. Everything contains energy including all forms of matter and so all objects. Energy is ...
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The frequency of electromagnetic radiation (light) refers to the number of wave-cycles of an electromagnetic wave that pass a given ...
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Hertz (Hz)

The hertz (symbol: Hz) is a unit used to measure the frequency of electromagnetic waves. Hertz are used when measuring ...
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A nanometre is a unit of measurement of the wavelength of electromagnetic radiation ...
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Wavelength is a measurement from any point on the path of a wave to the same point on its next ...
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