Radiation Definition and Examples

What Is Radiation?

While not radioactive, a candle does emit radiation in the forms of heat and light.
While not radioactive, a candle does emit radiation in the forms of heat and light. an aruni photography, Getty Images

Radiation and radioactivity are two misunderstood concepts. Here is the definition of radiation and a look at how it differs from radioactivity.

Radiation Definition

Radiation is the emission and propagation of energy in the form of waves, rays or particles. There are three main types of radiation:

  • Non-ionizing radiation: This is the release of energy from the lower-energy region of the electromagnetic spectrum. This includes light, radio, microwaves, infrared (heat), and ultraviolet light.
  • Ionizing radiation: This is radiation with sufficient energy to remove an electron from an atomic orbital, forming an ion. Ionizing radiation includes x-ray, gamma rays, alpha particles, and beta particles.
  • Neutrons: Neutrons are particles found in the atomic nucleus. When they break off of the nucleus, they have energy and act as radiation.

Examples of Radiation

Radiation includes emanation of any portion of the electromagnetic spectrum, plus it includes the release of particles. Examples include:

  • A burning candle emits radiation in the form of heat and light.
  • The Sun emits radiation in the form of light, heat, and particles.
  • Uranium-238 decaying into Thorium-234 emits radiation in the form of alpha particles.
  • Electrons dropping from one energy state to a lower state emit radiation in the form of a photon.

Difference Between Radiation and Radioactivity

Radiation is the release of energy, whether it takes the form of waves or particles. Radioactivity refers to the decay or splitting of an atomic nucleus. A radioactive material releases radiation when it decays. Examples of decay include alpha decay, beta decay, gamma decay, neutron release, and spontaneous fission.

All radioactive isotopes release radiation, but not all radiation comes from radioactivity.