Seebeck effect: a standalone construct

Thomas Johann Seebeck first observed the phenomenon in 1821 and described it in his 1826 paper Ueber die magnetische Polarisation der Metalle und Erze durch Temperaturdifferenz, reporting that a closed loop of two dissimilar conductors deflects a nearby compass needle when its two junctions are held at different temperatures. Seebeck read the deflection as magnetism, but it is now understood as the direct thermoelectric effect: a temperature difference along a conductor pushes its mobile charge carriers from the hot end toward the cold end, producing a voltage, and because two different materials respond by different amounts, joining them into a loop leaves a net voltage that can be read at the open ends. The size of the response for a given material is its Seebeck coefficient, also called thermopower, defined as the voltage produced per degree of temperature difference and reported in volts per kelvin, usually only microvolts per kelvin in metals and larger in semiconductors. The effect is the working principle of the thermocouple, the pairing of two wires used to measure temperature from the voltage at their junction, and of thermoelectric generators that convert heat directly into electric power with no moving parts. It is one of three linked thermoelectric effects: the reverse process in which a current carries heat is the Peltier effect, and the related heating or cooling along a current-carrying conductor that sits in a temperature gradient is the Thomson effect.[1][2][3]

Unit

A physical effect: a thermoelectric voltage set up by a temperature difference across dissimilar conductors, with the per-degree response (the Seebeck coefficient) reported in volts per kelvin

Recovery means

Not applicable

Measured by

Measured as the open-circuit voltage across a two-conductor junction divided by the temperature difference between its junctions, giving the Seebeck coefficient (commonly in microvolts per kelvin), under a controlled temperature gradient