Electromagnetic Waves (Cambridge (CIE) IGCSE Physics)

Revision Note

Katie M

Written by: Katie M

Reviewed by: Caroline Carroll

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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 Tips and Tricks

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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Katie M

Author: Katie M

Expertise: Physics

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.

Caroline Carroll

Author: Caroline Carroll

Expertise: Physics Subject Lead

Caroline graduated from the University of Nottingham with a degree in Chemistry and Molecular Physics. She spent several years working as an Industrial Chemist in the automotive industry before retraining to teach. Caroline has over 12 years of experience teaching GCSE and A-level chemistry and physics. She is passionate about creating high-quality resources to help students achieve their full potential.