Electromagnetic Waves – Learn

An electromagnetic wave is an electric and magnetic field oscillating together, perpendicular to each other. Electromagnetic waves are often referred to as being transverse electromagnetic waves.

Electromagnetic transverse waves are different from transverse matter waves:

  • Electromagnetic waves can travel through a vacuum.
  • They all travel at the speed of light (3\times 10^{ 8 }\cfrac { m }{ s } ) in a vacuum. They travel slower in other media.
  • Electromagnetic waves are self-propagating alternating electric and magnetic fields.
  • Because electromagnetic waves are hard to draw, we usually draw them as transverse matter waves.
  • The wavelength of an electromagnetic wave is the distance between the peaks of successive magnetic or electric field pulses.
  • We refer to the intensity of an electromagnetic wave rather than to its amplitude. The intensity of an electromagnetic wave depends on the number of photons in the beam. Each photon will have energy dependent on its frequency.
  • The period of an electromagnetic wave is the time for one wavelength to pass a given point.
  • The frequency of an electromagnetic wave is the number of wavelengths that pass a point each second. Frequency is measured in hertz (Hz).

The diagram below represents the electromagnetic spectrum. Each part of the spectrum covers a range of wavelengths and frequencies. The wavelengths and frequencies below reflect approximate measurements that apply to the different parts of the spectrum.

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