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Electromagnetic Waves (CIE IGCSE Physics: Co-ordinated Sciences (Double Award))
Revision Note
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
Visible light is just one small part of a much bigger spectrum: The electromagnetic spectrum
Exam 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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