How Does
How a Rheostat Works
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By eHow Contributing Writer
Rheostat Definition
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A rheostat is a simple device used to control the amount of current flowing through a circuit. A rheostat is a type of resistor. A resistor has that name because it resists the flow of electricity. Rheostats are variable (adjustable) resistors that have knobs or sliders that can be used to change their resistance. Rheostats are used in the circuits that control volume on stereos, light output on fixtures, and other electric circuits that have adjustable output levels.
Rheostat Construction
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A rheostat has a band of some resistive material attached on one end to an electric contact. The other contact touches the resistive material but can be moved. As the knob or slider is adjusted, the moving contact slides closer to or further away from the fixed contact. In knobs, the moving slider actually moves down along a spiral of graphite or another resistor; in sliders, it just moves along a straight strip.
How it Works
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Electricity is measured in voltage and amperage. Voltage is the amount of pressure the electricity exerts through the circuit, and amperage is the speed at which the electricity moves through it. The more resistance, the slower the electricity flows and the lower the amperage. When the moving contact is moved further away from the fixed one on the rheostat, the electricity has a greater distance to flow through the resistor. This increases the resistance, lowering the amperage of the electricity flowing through the rheostat.
eHow Article: How a Rheostat Works
