Wheatstone bridge

A circuit of four resistors arranged in a bridge, used to determine an unknown resistance by balancing the circuit until no current flows through its detector branch.

Bridge circuit: An electrical network with multiple paths arranged to compare voltages or currents between two points. The Wheatstone bridge is a resistive bridge circuit whose balance compares potentials across its middle branch.
Electrical resistance: The opposition a material or component offers to electric current, measured in ohms. The bridge compares known resistances with an unknown resistance.
Strain gauge: A sensor whose electrical resistance changes as it is stretched or compressed. A Wheatstone bridge converts the gauge's small resistance change into a measurable voltage.
Kelvin double bridge: A bridge circuit designed to measure very low resistances while reducing errors from lead and contact resistance. It modifies the Wheatstone arrangement for low-resistance measurements where wiring resistance matters.
Kirchhoff's circuit laws: Rules stating that currents balance at circuit junctions and voltage changes sum to zero around closed loops. They yield the current and voltage relations used to derive the bridge's balance condition.
Ohm's law: The relation stating that voltage across a conductor equals current through it multiplied by its resistance. It connects each resistor's voltage drop and current when deriving bridge balance.
Load cell: A transducer that converts force or weight into an electrical signal, commonly using strain gauges. Load cells commonly use bridge-connected strain gauges to detect small deformations.
Maxwell bridge: An alternating-current bridge circuit used to measure an unknown inductance by balancing against known components. Unlike the Wheatstone bridge's direct-current resistance comparison, it balances reactive components.
Voltage divider: A series circuit that produces an output voltage determined by the ratio of its resistances. Each side of the bridge acts as a voltage divider whose midpoint potentials must match at balance.
Electric potential: Electric potential energy per unit charge at a point, measured in volts. Balance means the two detector-branch endpoints have equal electric potential.

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