Long Waves to Short Waves




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

Long Waves to Short Waves

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

  1. Is an electromagnetic wave the same as a light wave?
  2. Is there a relationship between wavelength and colour?
  3. Can the wavelength of a wave be measured?
  4. Which has the longest wavelength, a red or a violet light wave?
  5. What is the range of wavelengths that correspond with what an observer might describe as green?

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 six electromagnetic waves. Each wave corresponds with a colour within the visible spectrum that an observer might recognise.

Remember that:

  • Electromagnetic waves, which are a form of electromagnetic radiation, propagating from a light source, travel through space and encounter different materials.
  • Colour is not a property of electromagnetic radiation, but an aspect of visual perception.
  • A human observer can distinguish between colours corresponding with many thousands of wavelengths of light in the visible spectrum. These colours are often called spectral colours.
  • The largest part of the electromagnetic spectrum is outside the wavelengths of visible light and so invisible to a human observer.
  • Beyond red are infrared, microwaves and radio waves for example. Some radio waves have a wavelength longer than a kilometre (1000 metres).
  • Beyond violet are ultraviolet, X-rays, and gamma rays for example. Some gamma rays have a wavelength of one billionth part of a metre.
  • There are no properties of electromagnetic radiation that distinguish visible light from other parts of the electromagnetic spectrum.
  • Objects appear to be different colours to an observer depending on the wavelengths, frequencies and amplitude of visible light at the moment it strikes the retina at the back of the eye.

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.


Things appear coloured to an observer because colour corresponds with a property of light that is visible to the human ...
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Electromagnetic spectrum

The electromagnetic spectrum includes electromagnetic waves with all possible wavelengths of electromagnetic radiation, ranging from low energy radio waves through ...
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ROYGBV is an acronym for the sequence of hues (colours) commonly described as making up a rainbow: red, orange, yellow, ...
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Visible light

Visible light is the range of wavelengths of electromagnetic radiation perceived as colour by human observers. Visible light is a ...
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Visible spectrum

The visible part of the electromagnetic spectrum is called the visible spectrum. The visible spectrum is the range of wavelengths ...
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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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