Electromagnetic Waves (Cambridge (CIE) IGCSE Physics)
Revision Note
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
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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