Type of waveWavelength Range/mMethod of ProductionPropertiesApplications and Uses

Gamma raysx10-12

Emitted during radioactive decay 1. very penetrating 2. produce weak ionization 3. produce weak fluorescence 4. affect photo filmMedicine in chemotherapy

X-raysx10-10

Produced by firing electrons at a metal target 1. ionizing2. affect photo film3. penetrating4. produces fluorescence5. can produce photoelectric emissionUsed to look at bones because it can penetrate through skin and flesh

Ultravioletx10-8

1.Emitted by the Sun2.Electron energy level changes in atoms1. produces ionisation, fluorescence 2. initiates chemical reactions3. absorbed by plate glass4. produces the photoelectric effect5. affects photo filmTanning

Visible light7 x10-7 to 4x10-7

1.Emitted by the Sun2.Electron energy level changes in atoms1. starts chemical reactions (eg photosynthesis)2. affects photo filmVision

Infraredx10-5

1.Emitted by hot objects2.Molecular vibration3.Electron energy level changes in atoms 1. transfer of heat energy to materials2. modulation for short distance control (eg TV remotes)Conventional cooking

Microwavesx10-3 to x10-2

Produced by changing currents in a conductor 1. modulation of waves for communication2. resonance with molecules, producing heatMicrowave cooking and communication

Radiox 1 Produced by changing currents in a conductorwaves can be modulated for communicationCommunication and media

All the waves in the electromagnetic spectrum... travel the same speed in a vacuum; can be reflected, refracted, diffracted and polarised;are transverse waves.

Radio Waves:Used for radio broadcasts, amateur radio, television, and mobile phones. Different parts of the radio spectrum have been allocated to the various services. Radio waves have a much longer wavelength that light waves. The longest waves are several kilometers in length. The shortest ones are only millimeters long.They make the electrons in a piece of copper wire move; this means that they generate electric currents in the wire. In fact it works both ways: alternating currents in a copper wire generate electromagnetic waves, and electromagnetic waves generate alternating currents. The electric currents at radio frequencies (rf) are used by radio and television transmitters and receivers. I use frequencies of 145MHz (VHF), 14MHz (20m HF) and 3.7MHz (80m HF).Microwaves:Microwaves have such a short wavelength that they are very easily absorbed by water. This is why they are used in microwave ovens. What happens is that when the water in your TV dinner absorbs the microwaves, the energy of the microwaves is converted into heat: it makes the water molecules vibrate faster. Some people are frightened that the radio waves coming out of their mobile phones are short enough to cook their brains.Infra Red:These radio/light waves have a very short wavelength; their wavelength is longer than visible light. Infra-red can be detected by special infra-red film. If the police or MI5 shine an infra-red light on you they will be able to take a picture of you using infra-red film: you will not know that they have taken your photo. Animals like the pit-viper have infra-red detectors so that they can find their prey in the dark. The Visible Spectrum:Richard Of York Gave Battle In Vain. = Red, Orange, Yellow, Green, Blue, Indigo, and Violet. are the colours of the visible spectrum. We cannot see Infra-red, but we can feel it warm our skin when we sit in the sun. Infra-red has a longer wavelength (less energy) than Red light. We cannot see Ultra-violet light, but we feel our skin has been burnt by the sun if we were in the sun too long yesterday. It is the Ultra-violet which is thought to cause skin cancer. UV light has a shorter wavelength (more energy) than visible light.Ultra Violet:These waves have very high energy and very short wave lengths; shorter than visible light. Some animals like honey bees can see ultra-violet light. Some plants have white flowers, at least you think that they are all white, but they may appear to be different colours to a honey bee because of the amounts of ultra-violet light which they reflect.X-Rays:X-Rays have so much energy and such a short wavelength that they can go right through you. However, they cannot get through bone as easily as they can get through muscle. This is because your bones contain so much Calcium. If you have never had an X-Ray, try jumping off a high wall and breaking a bone. The doctors will soon have you fixed: they take an X-Ray to see which bones have been broken. If you break the bone in enough places they will have to use steel bolts to fix you up.X-Ray can also be used to find other problems in your body. If the doctors want to look for ulcers in your guts, they can give you a Barium meal. Like Calcium, the Barium absorbs X-Rays so the doctors can look at parts of your guts and find your ulcers. You get ulcers byGamma Rays:These are nasty ones. They have very high energy and will even go through metals. So they can be used for finding tiny cracks in metals. You cannot see the hairline cracks in an aeroplane wing with the naked eye. How would you like the wings to fall off the plane on your summer holiday flight to Neasden or wherever it is that you go. If the plane has been thoroughly checked you should be safe. Some radioactive materials produce gamma rays. Gamma rays and X-Rays can cause cancer, but gamma rays can also be used to destroy cancer cells: this is radio-therapy.