Electricity From Heat If one end of an iron wire is joined to one end of a copper wire to form what is called a thermocouple, a small amount of electricity will be generated when the junction is heated. The amount of current or voltage is in proportion to the heat applied. Other dissimilar metals will also generate electricity in the same way, but in different amount. Temperatures too high for measurement by conventional thermometers can be measured by feeding the electricity generated in a thermocouple into an instrument that is essentially a voltmeter calibrated to read degrees of temperature. In addition, a thermocouple may be installed in a furnace, and the electricity generated can be fed into an electric control system to govern the amount of fuel fed to the furnace, automatically holding the furnace to a constant temperature.
