Electrical principles, like voltage, amperage and resistance, can be described as cars passing along the roadway. Voltage would be the vehicle's speed, amperage would be the number of vehicles on the road at the same time, and resistance would be the potholes in the road's surface.

Basically, electricity is a supply of atoms with an excess number of

electrons. The flow of electricity would then be the actual exchange of electrons from atom to atom (see Figure 1). Keeping with the cars-on-the-roadway analogy, we'll also discuss diodes, DC and AC current, and define the term "short circuit" in this article.

Diodes are one-way traffic cops. They only allow the electrons to flow in one direction, similar to a "one way" sign on the streets; they are the "check valve" in an electrical circuit. The two ends of a diode are called an anode (+) and a cathode (-). The cathode end of the diode has an extra amount of electrons stored in its materials. The anode has a shortage of electrons. Electrically, the anode has "holes" that happily accept those extra electrons from the cathode side. The light bulb is glowing because at the junction between the anode and cathode, the "holes" and the electrons meet. The electrons then fill in the "holes," lower the diode's resistance, and current then flows through the circuit.

The terms direct current (DC) and alternating current (AC) refer to the manner in which the electricity flo...