# Volt

The volt (symbol: V ) is the unit IF of electromotive Force and Potential difference (or tension).

One owes this name with Alessandro Volta, inventive Italian of the battery in 1800.

It corresponds to the potential difference electric which exists between two points of a circuit traversed by a constant current of 1 amp when the power dissipated between these two points is equal to 1 Watt.

$\ mbox \left\{V\right\} = \ dfrac \left\{\ mbox \left\{W\right\}\right\} \left\{\ mbox \left\{has\right\}\right\} = \ dfrac \left\{\ mbox \left\{J\right\}\right\} \left\{\ mbox \left\{C\right\}\right\} = \ dfrac \left\{\ mbox \left\{m\right\} ^2 \ cdot \ mbox \left\{kg\right\}\right\} \left\{\ mbox \left\{S\right\} ^ \left\{3\right\} \ cdot \ mbox \left\{has\right\}\right\}$.

## Comparison with hydraulics

According to the analogy with hydraulics, often used to explain the electrical circuits by comparing them with pipes filled with water, the tension is comparable with the pressure of water; it determines the speed to which the electrons circulate in the circuit. The current (in amp), according to the same analogy, is a measurement of the volume of water which circulates at a given point, this flow being determined by the pressure (tension).

## Current nominal voltages

Nominal voltages of various familiar sources:
• Potential of action of the nervous Cell: around 75 mV

• Rechargeable battery in NiMH or NiCd: 1,2 V
• Battery with the mercury: 1,355 V
• not-refillable alkaline Pile (C. - with-D. piles AAA, AA, C and D): 1,5 V
• refillable Battery with lithium-polymer: 3,75 V
• Food of the circuits of logic to coupled transistors (circuit TTL): 5 V
• Pile PP3: 9 V
• electric System of an Automobile : 12 V
• Faceplate standard (effective stress):
• the Lightning: Very variable, generally in the neighborhoods of 100 MV.

Simple: Volt Zh-min-nan: Bó͘-lú-to͘h

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