Wheatstone bridge

Wheatstone bridge, electric circuit used for comparing or measuring resistance. Four resistors, including the unknown one, are connected in a square, with a battery between one pair of diagonally opposite corners and a sensitive galvanometer between the other. When no current flows through the meter, the products of opposite pairs of resistances are equal. Similar bridge circuits are used for impedance measurement.

See also: Electric circuit; Wheatstone, Sir Charles.