Electromagnetic Waves (Cambridge (CIE) IGCSE Physics): 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

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 (opens in a new tab) 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

$3.0\times {10}^8\mathrm{m}/\mathrm{s}$

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