Resistance: Difference between revisions
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<onlyinclude>Resistance is similar to [[friction]] for [[electrical energy]]; resistance causes the [[electrical energy]] to be lost as heat ([[thermal energy]]), just like friction causes [[mechanical energy]] to be lost as [[heat]].</onlyinclude> | <onlyinclude>Resistance is similar to [[friction]] for [[electrical energy]]; resistance causes the [[electrical energy]] to be lost as heat ([[thermal energy]]), just like friction causes [[mechanical energy]] to be lost as [[heat]].</onlyinclude> | ||
Resistance is a measure of how much voltage an electrical element needs in order to increase the electrical [[current]]. The actual resistance depends on both the [[resistivity]] and the geometry of the wire. Resistivity is a property of the material ( | Resistance is a measure of how much [[voltage]] an electrical element needs in order to increase the electrical [[current]]. The actual resistance depends on both the [[resistivity]] and the geometry of the [[wire]]. Resistivity is a property of the material ([[metal]]s have low resistivity; [[wood]] has high resistivity). Resistivity of a material helps determine how well it will conduct [[electricity]]. A higher resistance results in a lower current for a given voltage. Resistance is measured in [[Ohm]]s (Ω). | ||
While it is easy to think of resistance as a bad thing, many electronic | While it is easy to think of resistance as a bad thing, many electronic [[circuit]]s require [[resistor]]s (objects with high resistance, deliberately put in a circuit) to function! The resistance of a wire increases as its length increases and decreases as its thickness increases. When conducting [[electricity]] over long distances, like the [[electrical grid]], it's important to keep the resistance as low as possible. The wires in the electrical grid have a low resistivity and fairly large cross-sectional areas to allow them to conduct electricity over long distances with minimal loss. Please play with the simulation below to see how these values affect resistance. | ||
==PhET: Resistance in a wire== | ==PhET: Resistance in a wire== | ||
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<html><iframe src="http://phet.colorado.edu/sims/html/resistance-in-a-wire/latest/resistance-in-a-wire_en.html" width="800" height="600"></iframe></html> | <html><iframe src="http://phet.colorado.edu/sims/html/resistance-in-a-wire/latest/resistance-in-a-wire_en.html" width="800" height="600"></iframe></html> | ||
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Revision as of 20:08, 17 September 2015
Resistance is similar to friction for electrical energy; resistance causes the electrical energy to be lost as heat (thermal energy), just like friction causes mechanical energy to be lost as heat.
Resistance is a measure of how much voltage an electrical element needs in order to increase the electrical current. The actual resistance depends on both the resistivity and the geometry of the wire. Resistivity is a property of the material (metals have low resistivity; wood has high resistivity). Resistivity of a material helps determine how well it will conduct electricity. A higher resistance results in a lower current for a given voltage. Resistance is measured in Ohms (Ω).
While it is easy to think of resistance as a bad thing, many electronic circuits require resistors (objects with high resistance, deliberately put in a circuit) to function! The resistance of a wire increases as its length increases and decreases as its thickness increases. When conducting electricity over long distances, like the electrical grid, it's important to keep the resistance as low as possible. The wires in the electrical grid have a low resistivity and fairly large cross-sectional areas to allow them to conduct electricity over long distances with minimal loss. Please play with the simulation below to see how these values affect resistance.
PhET: Resistance in a wire
The University of Colorado has graciously allowed us to use the following Phet simulation. Explore the simulation to see how resistance changes depending on geometry and resistivity: