apt-, ept-

1. A pair of dissimilar electrical conductors (such as platinum and platinum-rhodium, or copper and constantan), so joined that an electromotive force is developed by the thermoelectric effects when the junctions are at different temperatures; used for measuring temperature differences. Also known as thermojunction.
2. A device consisting of two different metallic conductors that are connected at both ends, producing a loop in which heat is converted into electrical current when there is a difference in temperature between their two junctions; used to measure the temperature of a third substance by connecting it to both junctions and measuring the voltage generated between them.