THE ELECTROMAGNETIC SPECTRUMBy Rishi Maran

Click on a type of wave

Gamma Rays

• WAVELENGTH - <10^(-11) m• FREQUENCY – > 3 x 10^19 Hz• Extremely high energy waves• Nuclear energy released from

nucleus of radioactive isotopes– E.g. uranium and plutonium

• Detected with a Geiger Counter

Uses• Radiotherapy• Tracer• Sterilise food

Ultraviolet (UV)

• WAVELENGTH – 1 * 10^(-8) – 4 * 10^(-7) m

• FREQUENCY – 7.5 * 10(14) – 3 * 10^(16) Hz

• Found in sunlight and mercury vapour lamps

• Detected with skin, photographic film & fluorescent chemicals

• Small amount of UV is vital– Helps produce Vitamin D– Too much causes damage to the skin

Uses• Kill bacteria• Astronomy research• Fluorescence

Visible Light

• WAVELENGTH- 4 * 10^(-7) – 7 * 10^(-7) m

• FREQUENCY- 4*10^(14) - 7.5 * 10^(14) Hz

• The only electromagnetic waves we can see

• Includes colours of the rainbow– ROYGBIV– Each colour has a different

wavelength– Red has longest wavelength, and

Violet has shortest wavelength– When all waves are seen

together, they make white light.

Uses• Seeing• Plants use it for photosynthesis• CD players and laser printers

Infrared (IR)

• WAVELENGTH- 7 * 10^(-7) – 1 * 10^(-3) m

• FREQUENCY- 3 * 10^(11) - 4 * 10^(14) Hz

• Often associated with heat• Released from vibrating atoms and

molecules– Hotter the object, the more the

energy released as IR radiation

Uses• Thermal Imaging• Night vision goggles• TV remote controls

Microwaves

• WAVELENGTH- 1 * 10^(-3) – 1 * 10^(-1) m

• FREQUENCY- 3 * 10^(9) – 3 * 10^(11) Hz• Sometimes called short-wave radio waves• Detected by parabolic dish antennas• Generated by vibrating electrons in

electrical devices• Able to pass through the ionosphere of

the atmosphere.

Uses• Satellite communications• Radar• Mobile phones• Microwave ovens

Radio Waves

• WAVELENGTH- > 1 * 10^(-1) m• FREQUENCY- < 3 * 10^(9) Hz• Generated by vibrating

electrons.• Have an extremely large

wavelength.– Long (ground) radio waves

bend to follow the Earth’s surface.

– Short (sky) radio waves reflect from the ionosphere as they cannot pass through. Uses

• Global communication• Radio and television

broadcasting.