The electromagnetic spectrum (EMS) is the general name given to the known range of electromagnetic radiation. Wavelengths increase from approximately 10-18 m to 100 km, and this corresponds to frequencies decreasing from 3 × 1026 Hz to 3 ×103 Hz.
Electromagnetic radiation can be expressed in terms of energy, wavelength, or frequency. Frequency is measured in cycles per second, or Hertz. Wavelength is measured in meters. Energy is measured in electron volts.
The different types of radiation are defined by the the amount of energy found in the photons. Radio waves have photons with low energies, microwave photons have a little more energy than radio waves, infrared photons have still more, then visible, ultraviolet, X-rays, and, the most energetic of all, gamma-rays
