Key ideasKey ideas

The electromagnetic spectrum is made up of radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays. They have different wavelength ranges.

12.3 Waves of the electromagnetic spectrum

Electromagnetic wave

Typical wavelength Source Detector Application

Radio waves

Microwaves

Infrared radiation

radio communication,

radio and TV broadcasting

10–1 m – 104 m

radio and TV

transmitterantenna

10–2 m microwave transmitter

microwave receiver

microwave oven, satellite

communication, radar

10–4 mWarm or

hot objects, the Sun

skin, phototransistor,

blackened thermometer

thermography, infrared viewer, infrared lamp, remote control, auto-focus ca

mera

Electromagnetic wave

Typical wavelength Source Detector Application

Visible light

Ultraviolet radiation

X-rays 10–10 m

10–8 m

10–7 mhot objects,

the Sun, fluorescent materials

very hot objects, the

Sun, mercury lamp

X-ray tube

human eyes, photographic

film

fluorescent materials

photographic film

illumination

production of vitamin D,

sterilization, checking

banknotesmedical

diagnosis, checking for

cracks in joints

Electromagnetic wave

Typical wavelength Source Detector Application

Gamma rays 10–12 m radioactive substances

photographic film, Geiger-

Muller counter

kill cancer cells, sterilize

food