Wheatstone bridge

Definition

A Wheatstone bridge is an electrical circuit used to precisely measure unknown resistances by balancing two legs of a bridge circuit. It consists of four resistors, a voltage source, and a galvanometer.

5 Must Know Facts For Your Next Test

1. The Wheatstone bridge is balanced when the ratio of the resistances in one leg is equal to the ratio in the other leg.
2. In its balanced state, the current through the galvanometer is zero.
3. It can be used to measure very small changes in resistance accurately.
4. The general formula for balance is $\frac{R_1}{R_2} = \frac{R_3}{R_x}$, where $R_x$ is the unknown resistance.
5. Adjusting either $R_1$, $R_2$, or $R_3$ will help achieve balance and determine the value of $R_x$.

Review Questions

Related terms

Galvanometer:

An instrument used to detect and measure small electric currents by deflection of a needle.

Null Measurements: A method in which instruments are adjusted until they show no response (null), indicating that certain conditions have been met.

Resistor:

A passive electrical component that provides resistance to current flow within a circuit.