The Wheatstone Bridge
Created | Updated Jun 6, 2003
The Wheatstone Bridge was invented by British mathematician Samuel Christie and popularized by Sir Charles Wheatstone (b. Feb. 6, 1802, Gloucester, Gloucestershire, Eng.- d. Oct. 19, 1875, Paris) in 1943.
The Bridge is a very sensitive electrical circuit used to accurately measure resistance. Therefor it can also be used to detect small changes in a resistor (due to e.g. a defect in the resistor, or a temperature change).
The bridge consists of four resistors arranged in a diamont shape. Two of the resistors are known, one is unknown and one is an adjustable resistor.
The voltage is measured between points a and b (Vab) in the drawing, by a voltage meter (a galvanometer for example). When Vab = 0 the bridge is said to be "balanced". To balance the bridge you must adjust the adjustable resistor until Vab = 0. When the bridge is balanced the unknown resistor can be calculated by: R1*Radj = R2*Runk.
The Bridge is a very sensitive electrical circuit used to accurately measure resistance. Therefor it can also be used to detect small changes in a resistor (due to e.g. a defect in the resistor, or a temperature change).
The bridge consists of four resistors arranged in a diamont shape. Two of the resistors are known, one is unknown and one is an adjustable resistor.
The voltage is measured between points a and b (Vab) in the drawing, by a voltage meter (a galvanometer for example). When Vab = 0 the bridge is said to be "balanced". To balance the bridge you must adjust the adjustable resistor until Vab = 0. When the bridge is balanced the unknown resistor can be calculated by: R1*Radj = R2*Runk.
