Wheatstonesilta

Wheatstone's Bridge, often referred to as Wheatstonesilta in some contexts, is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. It was invented by Samuel Hunter Christie in 1833 but was improved and popularized by Sir Charles Wheatstone, after whom it is named.

The circuit consists of four resistors arranged in a diamond shape. Two arms have known resistances (R1 and R2), and the third arm contains a variable resistor (R3) with a known resistance that can be adjusted. The fourth arm contains the unknown resistor (Rx). A galvanometer, a sensitive instrument for detecting small electric currents, is connected between the junction of R1 and R3, and the junction of R2 and Rx.

When the bridge is balanced, there is no current flowing through the galvanometer. This occurs when the ratio of the resistances in the known arms equals the ratio of the resistances in the arms containing the variable and unknown resistors. Mathematically, this balance condition is expressed as R1/R2 = R3/Rx. By adjusting R3 until the galvanometer reads zero, the unknown resistance Rx can be calculated using the formula Rx = (R3 * R2) / R1.

Wheatstone's Bridge is a fundamental circuit in electronics and is used in various applications, including strain gauges, resistance temperature detectors (RTDs), and in measurement devices for humidity, pressure, and light intensity. Its sensitivity and accuracy make it a valuable tool for precise resistance measurements.