The Electromagnetic Spectrum
Electromagnetic waves occur when there is a disturbance in the electric force field, which is made up of charged particles like electrons and protons. Different kinds of waves are determined by how long their wavelengths are. A wavelength can be determined by how many times a wave completes its cycle over a set period of time. The shorter the wavelength, the more powerful the wave is and the more energy it has.
The longest wavelengths, like TV and radio waves can be about 20 meters or longer. They are used to transport information without using wires, and can even go through space. They work by sending electric currents through conductors called antennae which send and receive the wave impulses. These radio waves can communicate with submarines under water, create the radio we can listen to, and communicate into outer space.
There are also microwaves, which are between a millimeter and a meter long. We all think of the microwave ovens we use in the kitchen, but this is only one of their uses. They care also used in radar that can detect the range and speed of things. They are also useful for GPS and navigation systems.
Infrared waves are about 0.00001 meters. Infrared means “below red” in latin, because they are directly below visible light on the electromagnetic spectrum. They can be used for surveillance, night vision, tracking, wireless communication, and they are used extensively in weather forecasting.
Visible light is about 0.0000006 meters long in wavelength. The colors we see also have a spectrum of their own: red, orange, yellow, green, blue, indigo, violet. They also go in order of wavelength, with red being the longest and violet having the shortest length.
Ultraviolet, or UV rays are about 0.00000003 meters, and are usually associated with exposure to the sun. They can cause cancer, blisters, or scars if exposed too long. They are used in medicine for killing bacteria and viruses and sterilize equipment. They are also used to make blacklights, and experiments show that birds and insects can see UV light.
X-rays which are about 0.0000000009 meters, are used in medicine to photograph the bones and internal organs of a patient. And the highest energy waves are gamma which are produced through high energy protons or radioactive decay. They are so powerful that it takes large mass objects to absorb their energy. They can easily cause damage to living tissue, and are the most dangerous in a nuclear explosion.