Potential_difference

In physics, the potential difference is a quantity related to the amount of energy that would be required to move an object from one place to another against various types of forces. The term is most frequently used as an abbreviation of \'electrical potential difference\', but it also occurs in many other branches of physics. Only changes in potential or potential energy (not the absolute values) can ever be measured.

Explanation

Potential difference is the difference in some quantity between two points in a conservative vector field of that quantity. Some examples are listed below.

• In electrical engineering, electrical potential difference is the voltage present between two points, or the voltage drop transversely over an impedance (from one extremity to another). Rudolf F. Graf, "Potential difference", Dictionary of Electronics; Radio Shack, 1974-75. Fort Worth, Texas. ISBN B000AMFOZY It is related to the energy that would be required to move a unit of electrical charge from one point to the other against the electrostatic field that is present. As potential difference increases, the current increases as well. Units: joules per coulomb = volts
• In mechanics, the gravitational potential difference between two points on Earth is related to the energy that would be required to move a unit mass from one point to the other against the Earth\'s gravitational field. Units: joules per kilogram.
• In biology, the potential difference is the −65 mV difference in electrical charge between the internal components of a resting axon of a nerve compared to its external surface.
• In fluid systems the potential difference is the difference in pressure. Units: pascals.
• In thermal systems the potential difference is the difference in temperature. Units: kelvins.

In some engineering fields, "potential" is sometimes described as the \'across\' variable, whereas flux is the \'through\' variable. The product of the flux and the potential difference is the power, which is the time rate of change of energy.

The work done per unit charge is a measure of the amount of the accumulated or a measure of the potential energy that has been established. The greater the accumulated charge, more work has to be done in the movement of the charges because Coulomb forces of repulsion and attraction are larger. The work done per unit charge is known as potential. The unit of potential is the volt, and 1 V is equal to 1 J/C. The unit of electric potential was named after an Italian physicist Alessandro Volta.

If v is the voltage in volts, and w is the work in joules (J), and q is the charge in coulombs (C), then $v\; =\; \{\; dw\; \backslash over\; dq\; \}$ $\{\backslash mathrm\{J\}\; \backslash over\; \backslash mathrm\{C\}\}\; \backslash \; or\; \backslash \; \backslash mathrm\{V\}$

See also

• Extra low voltage
• Low voltage
• High voltage
• Extra high tension (EHT), extra high voltage
• Mains electricity (an article about domestic power supply voltages)
• List of countries with mains power plugs, voltages and frequencies
• Potential energy
• SI electromagnetism units

References

External links

• Potential vs. Potential difference

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