# Peltier effect

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## Peltier effect

(pĕl`tyā): see thermoelectricitythermoelectricity,
direct conversion of heat into electric energy, or vice versa. The term is generally restricted to the irreversible conversion of electricity into heat described by the English physicist James P.
.

## Peltier effect

A phenomenon discovered in 1834 by J. C. A. Peltier, who found that at the junction of two dissimilar metals carrying a small current the temperature rises or falls, depending upon the direction of the current. In view of experiments, which establish that the rate of intake or output of heat is proportional to the magnitude of the current, it can be shown that an electromotive force resides at a junction. Electromotive forces of this type are called Peltier emf's. See Seebeck effect, Thermoelectricity, Thomson effect

## Peltier Effect

an evolution or absorption of heat when an electric current flows through a contact, or junction, between two dissimilar conductors. Heat is evolved when the current passes in one direction across the junction and absorbed when the current passes in the other direction. The effect was discovered by J. Peltier in 1834.

The rate Q of heat liberation or absorption is proportional to the magnitude of the current I flowing across the junction: Q = ΠI. The Peltier coefficient Π = – TΔα, where T is the absolute temperature in °K and Δα is the difference between the thermoelectric coefficients of the conductors. Theoretical concepts permit the Peltier coefficient to be formulated in terms of the microscopic characteristics of conduction electrons. The effect is particularly large for semiconductors, a fact made use of in the design of semiconductor cooling and heating devices.

## Peltier effect

[pel′tyā i‚fekt]
(physics)
The phenomenon in which heat is evolved or absorbed at the junction of two dissimilar metals carrying a small current, depending upon the direction of the current.
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