Thermoelectricity

Clicking a thumbnail on this web page (http://chemistry.beloit.edu/edetc/cineplex/thermoelectric/index.html) shows a movie of that demonstration.

Between the two large heat sinks are several semiconductor crystals. A temperature differential between the two heat sinks causes a current to flow. This is show with the aid of the propeller connected to a DC motor. When the heat sinks are inverted, first the propeller stops and then reverses direction of rotation.

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