follow Dictionary.com

Get the details behind our redesign

variable resistor

variable resistor in Science
variable resistor  
See under resistor.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
Cite This Source
Encyclopedia Article for variable resistor

rheostat

adjustable resistor used in applications that require the adjustment of current or the varying of resistance in an electric circuit. The rheostat can adjust generator characteristics, dim lights, and start or control the speed of motors. Its resistance element can be a metal wire or ribbon, carbon, or a conducting liquid, depending on the application. For average currents, the metallic type is most common; for very small currents, the carbon type is used; and for large currents the electrolytic type, in which electrodes are placed in a conducting fluid, is most suitable. A special type of rheostat is the potentiometer, an instrument that measures an unknown voltage or potential difference by balancing it, wholly or in part, by a known potential difference. A more common potentiometer is simply a resistor with two fixed terminals and a third terminal connected to a variable contact arm; it is used for such purposes as a volume control in audio equipment.

Learn more about rheostat with a free trial on Britannica.com
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
Cite This Source

Word of The Day

Word Value for variable

13
16
Scrabble Words With Friends