Shining visible radiation from a torch beam onto a hand lights the hand up because the hand has been exposed to light.

Exposing objects to beams of radiation is called irradiation. The term applies to all types of radiation, including radiation from the nuclei of atoms.

Irradiation from radioactive decay can damage living cells. This can be put to good use as well as being a hazard.

Irradiation for sterilisation

Irradiation can be used to preserve fruit sold in supermarkets by exposing the fruit to a radioactive source - typically cobalt-60. The gamma rays emitted by the cobalt will destroy any bacteria on the fruit but will not change the fruit in any significant way. The process of irradiation does not cause the irradiated object to become radioactive.

Advantages and disadvantages of irradiation


  • Sterilisation can be done without high temperatures.
  • It can be used to kill bacteria on things that would melt.


  • It may not kill all bacteria on an object.