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Electronic Circuits
Before the invention of computers, people used the abacus, mechanical calculators, and electro-mechanical calculators to help process information. These devices were relatively slow because they relied on moving parts to process information. Inside a computer, information is rapidly processed using electronic circuits that do not have physical components that move.
Electrical Circuits and Terms
Electrical effects result when an imbalance of electric charge—an excess of positive or negative particles that are parts of atoms—attempts to balance itself. If the electric charge has a complete pathway to follow, the charge flows. This flow is called electrical current. The complete pathway is called an electrical circuit.
Circuits carry the electricity needed to do a defined task. The task is referred to as the electrical load. In our homes, for example, some circuits are designed to carry electricity through lightbulbs to light a room. Other circuits carry electricity to heat the elements on a kitchen stove. In a computer, circuits carry information during input, storage, information processing, and output.
Electrical current in a circuit behaves like water flowing in the water pipes of your house. Getting water to the kitchen sink requires four things: a suitable amount of water, a pipe to carry the water, a pressure difference between the source of the water and the tap, and a tap to turn the flow of water on or off.
Getting electricity to the kitchen toaster requires four things: a quantity of moving electrons, material that will carry these electrons to the toaster from the source of the electrons, a pressure difference between the source (power station) and the wall outlet, and a switch to turn the current on or off.
Simple electrical circuits consist of four parts—the conducting path, the electrical load, the power source, and a switch.
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Electric charge: The potential of electrons or protons to attract each other |
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Electrical current: The movement of electrons from one atom to another |
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Electrical load: Any component or circuit that consumes power delivered to it by a power source |
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Switch: Any device that allows the flow of electricity in a circuit when turned on, thereby completing the circuit pathway, or stopping the flow of electricity when turned off by creating a break in the circuit pathway. |
Consider the following simple electrical circuit consisting of a battery, lightbulb, wires, and switch.
In this circuit, the wire is the conducting path, the battery is the power source, and the bulb provides the electrical load. The action on the circuit is controlled with the switch. When the switch in this circuit is closed, there is a complete electrical path from the battery to the lightbulb and back to the battery. The bulb will light up as the current flows through it. If the switch is open, the circuit pathway is incomplete and the bulb does not light up.
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