P1 - Electromagnetic Waves and Communication

Everything you need to know about electromagnetic waves for your physics ocr exam.

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Electromagnetic Spectrum

Radio waves



Visible light



Gamma rays.

As you go down the list, the frequency increases, but the wavelength decreases. Also, they become more dangerous to humans.

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Properties of Electromagnetic Waves

The properties depend on frequency and wavelength. As these change, its interaction with other things changes.

This includes;

  • the way it's absorbed
  • way it's reflected
  • way it's transmitted
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Dangers of Electromagnetic Waves

The waves with higher frequencies and shorter wavelengths (e.g. x-rays) are more dangerous to living cells because they have more energy.

When electromagnetic radiation is absorbed, it causes heating and ionisation, which means atoms can lose or gain electrons - and this is dangerous.

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Electromagnetic Waves in Communication

Radio waves are used in radios. Microwaves are used in mobile phones.

That's quite easy to remember, isn't it? All you need to know now is the advantages and disadvantages of using different types of signals.


  • using light, radio and electrical signals means it travels very fast
  • electrical wires and optical fibres carry lots of information at speed
  • information sent through optical fibres and electrical wires are quite secure
  • wireless communication is portable


  • radio signals can be easily intercepted
  • cables can be difficult to repair if they get broken
  • wireless communication relies heavily on location to pick up a good signal strength.
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