Basic electricity is described in many ways. When an electric circuit flows through a conductor, a magnetic field (or "flux") develops around the conductor. The highest flux density occurs when the conductor is formed into a coil having many turns. In electronics and electrical technology, a coil is usually known as an inductor. If a steady DC current is run through the coil, you would have an electromagnet – a device with the properties of a conventional magnet, except you can turn it on or off by placing a switch in the circuit.<br />Basic Electrical Theory<br />There are four basic electrical quantities that we need to know:<br />Current<br />Potential Difference (Voltage)<br />Power<br />Resistance<br />Electrical Current<br />Current is a flow of charge. Each electron carries a charge of 1.6 × 10-19 coulombs. This is far too small to be any use, so we consider electricity to flow in packets called coulombs. When there is a flow of 1 coulomb per second, a current of 1 amp is flowing. Current circuit electric is measured in ampères, or amps (A).<br />Potential Difference<br />Potential difference is often referred to as voltage. There are several ways of defining voltage; the correct physics definition is energy per unit charge, in other words, how big a job of work each lump of charge can do.<br />Power in a Circuit<br />Power in a circuit can be worked out using the simple relationship:<br />Power (W) = Voltage (V) × Current (A)<br />Electrical Resistant Behaviour<br />This is the opposition to the flow of an electric current.<br />There's reciprocity in the interaction between electron flow and magnetism. If you sweep one pole of a magnet quickly past an electrical conductor (at a right angle to it), a voltage will be momentarily "induced" in the conductor. The polarity of the voltage will depend upon which pole of the magnet you're using, and in which direction it sweeps past the conductor.<br />This phenomenon becomes more apparent when the conductor is formed into a coil of many turns.