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## Basic Electricity and Magnetism

Electric charge is created by the accumulation of electrons on an object. If an object becomes too negatively charged, it means it has an excess of electrons. Likewise, a positively charged object has less electrons.

The electricity that you receive in your wall socket that powers your lights and almost everything else in your house, even the computer you are staring at right now, is created by an electric current. Electric current is defined as the movement of electric charge. For example, a light bulb lights up because as the electrons move through the tungsten filament in the bulb, it heats and brightens up.

You may be wondering why you have two prongs in your electric plugs (you actually may have three; this will be explained later). Remember, electric current is made by moving charge. Therefore, if the electrons move in through one prong, they must move out through another. This is why you have two main prongs. Some outlets have three prongs. The third one, usually called the ground, is made for safety reasons. If you have a faulty electrical device, the charge may not move out through the other prong but instead move through you--basically electrocuting you (very bad). The third prong is usually connected to any metal casing around the device so that the charge will hopefully move into that prong instead of through you.

### Magnets

Magnetic fields are created by moving electric charge. Magnets have a north and south pole. A magnetic field is defined by the lines of force that go from the north to the south pole. The illustration to the right shows the imaginary field lines coming out of one pole and going into the other (click on the illustration for a VRML model of the field lines). Things that are naturally magnetic are magnetic because of the orientation of the moving electrons orbiting the nuclei in the atoms. Electromagnets are metals that become magnetic when a coil of wire with a electric current is wrapped around it. The current in the wire induces a magnetic field in the metal.

Magnetic fields in turn can also create electricity. For example, a rotating magnet can induce an electric current in a piece of wire. This is how many power plants operate. In a coal, oil, or nuclear power plant, water is heated and becomes steam, which is used to turn turbines. In a hydroelectric plant, water from a dam or waterfall is used to turn the turbines. These turbines spin magnets which create the electricity for your home.

Created by TQ Team 16600: Clyde Law, Chetan Taralekar, Jim Wang
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Team Coaches: Melanie Krieger, Chhaya Taralekar