Electromagnetic Waves (CIE IGCSE Physics: Co-ordinated Sciences (Double Award))

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Ann H

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Ann H

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Electromagnetic waves

  • The electromagnetic spectrum is arranged in a specific order based on the wavelengths or frequencies of the radiation in each region
    • Regions with a long wavelength have a low frequency and vice versa
  • The main regions of the continuous electromagnetic (EM) spectrum from longest to shortest wavelength are:
    • Radio waves
    • Microwaves
    • Infrared
    • Visible (red, orange, yellow, green, blue, indigo, violet)
    • Ultraviolet
    • X-rays
    • Gamma rays

The electromagnetic spectrum in order of decreasing wavelength

EM spectrum diagram, downloadable AS & A Level Physics revision notes

Visible light is just one small part of a much bigger spectrum: The electromagnetic spectrum

Examiner Tip

See if you can make up a mnemonic to help you remember the EM spectrum!

One possibility is:

Raging Martians Invaded Venus Using X-ray Guns

The electromagnetic spectrum is usually given in order of decreasing wavelength and increasing frequency i.e. from radio waves to gamma waves

Remember:

  • Radios are big (long wavelength)
  • Gamma rays are emitted from atoms which are very small (short wavelength)

Properties of electromagnetic waves

  • All electromagnetic waves travel at the same high speed in a vacuum
  • Electromagnetic waves are defined as:

Transverse waves that transfer energy from the source of the waves to an absorber

The speed of electromagnetic waves

Extended tier only

  • The speed of electromagnetic waves in a vacuum is

3.0 × 108 m/s

  • This is approximately the same speed as electromagnetic waves in air

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Ann H

Author: Ann H

Expertise: Physics

Ann obtained her Maths and Physics degree from the University of Bath before completing her PGCE in Science and Maths teaching. She spent ten years teaching Maths and Physics to wonderful students from all around the world whilst living in China, Ethiopia and Nepal. Now based in beautiful Devon she is thrilled to be creating awesome Physics resources to make Physics more accessible and understandable for all students no matter their schooling or background.