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voltage

Contributor(s): David Lewis

Voltage, also called electromotive force, is a quantitative expression of the potential difference in charge between two points in an electrical field. 

The greater the voltage, the greater the flow of electrical current (that is, the quantity of charge carriers that pass a fixed point per unit of time) through a conducting or semiconducting medium for a given resistance to the flow. Voltage is symbolized by an uppercase italic letter V or E. The standard unit is the volt, symbolized by a non-italic uppercase letter V. One volt will drive one coulomb (6.24 x 1018) charge carriers, such as electrons, through a resistance of one ohm in one second.

Voltage can be direct or alternating. A direct voltage maintains the same polarity at all times. In an alternating voltage, the polarity reverses direction periodically. The number of complete cycles per second is the frequency, which is measured in hertz (one cycle per second), kilohertz, megahertz, gigahertz, or terahertz. An example of direct voltage is the potential difference between the terminals of an electrochemical cell. Alternating voltage exists between the terminals of a common utility outlet.

A voltage produces an electrostatic field, even if no charge carriers move (that is, no current flows). As the voltage increases between two points separated by a specific distance, the electrostatic field becomes more intense. As the separation increases between two points having a given voltage with respect to each other, the electrostatic flux density diminishes in the region between them.

Also see current, resistance, and Ohm's Law for DC Circuits.

This was last updated in March 2019

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Finally...I've found the complete answer of my question. Thanks!
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May I just say I find it absolutely ridiculous to define a term using such esoteric language. Basically, one assumes, to be able to understand this, one must already be a well trained electrician or engineer, which is ironic as voltage seems to be a very basic term in their field. So in order for to learn about it, one must already be it. If you wanted to attract more users to this site, you would define your terms in less technical language so one can actually learn something.
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What kind of tool do you use to measure voltage?
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I found this helpful, but it would be nice if it were contrasted with the other measurements of electicity, such as amperage and current.
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Thank you very much. I got a perfect score of our test because of these.
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'Voltage can be direct or alternating.'
Are you really sure you want to phrase it like that? Even Britannica does not have 'Direct voltage' or 'Alternating voltage' definitions.
Most of the definitions I have came across would mention direct or alternating current not voltage. Are you completely sure the way you phrase it is correct?
Great article btw.
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thanks...for researching....:)
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Voltage is cool. Makes power. needs more dragons :)
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thank you'
i got full answer from this information,
i have another question '' what is the difference between  voltage and current"
please give answer... thank you..
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