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3.1 | |
Copper Media | |
| 3.1.4 | |
Current |
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Electrical current is the flow of charges
created when electrons move. In electrical circuits, the current is
caused by a flow of free electrons. When voltage, or electrical
pressure, is applied and there is a path for the current, electrons
move from the negative terminal along the path to the positive
terminal. The negative terminal repels the electrons and the positive
terminal attracts the electrons. The letter “I” represents current.
The unit of measurement for current is Ampere (Amp). Amp is defined as
the number of charges per second that pass by a point along a path.
If amperage or current can be thought of as the amount or volume of electron traffic that is flowing, then voltage can be thought of as the speed of the electron traffic. The combination of amperage and voltage equals wattage. Electrical devices such as light bulbs, motors and computer power supplies are rated in terms of watts. A watt is how much power a device consumes or produces. It is the current or amperage in an electrical circuit that really does the work. As an example, static electricity has very high voltage, so much that it can jump a gap of an inch or more. However, it has very low amperage and as a result can create a shock but not permanent injury. The starter motor in an automobile operates at a relatively low 12 volts but requires very high amperage to generate enough energy to turn over the engine. Lightning has very high voltage and high amperage and can do severe damage or injury.
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