electromagnetic spectrum

Electromagnetic waves that are classified in ascending order of energy (frequency); they propagate at the speed of light (300,000 km/s).

visible light

Electromagnetic radiation that is perceived by the human eye and ranges from red to violet.

gamma rays

Electromagnetic waves of very high frequency that are emitted by radioactive bodies; they are the most radiant and harmful rays and are used especially in treating cancer.

X-rays

Electromagnetic waves used especially in radiology; frequent exposure can be harmful.

ultraviolet radiation

Electromagnetic waves used especially to tan skin and in microscopy, medicine and lighting (fluorescent tubes).

infrared radiation

Electromagnetic waves emitted by warm objects; their many uses include heating, medicine, aerial photography and weaponry.

microwaves

Short electromagnetic waves; their many applications include radar detection and microwave ovens.

radio waves

Very long electromagnetic waves (about 1 meter) having low frequency; they are used to transmit information (television, radio).