Definition
A type of remote-indicating instrument circuit that measures position by comparing the inductance of two coils. As a movable iron core or armature shifts between the coils, the balance of inductance changes, and that change is converted into a meter reading at a remote display. Commonly used in aircraft fuel quantity, temperature, and position-indicating systems.
Plain English
A simple electrical circuit that senses the position of a moving part by comparing two coils, then sends that information to a gauge somewhere else in the aircraft.
Context Anchor
Seen in aircraft electrical, ignition, and avionics maintenance when a technician needs to measure or compare coils, windings, or similar electrical parts.
Derivation
Inductance comes from the Latin inducere, meaning 'to lead in' -- it describes how a coil 'leads in' a magnetic effect when current flows. Bridge refers to a balanced electrical circuit shaped so that two sides are compared against each other, like two halves meeting in the middle. Together, the term describes a circuit that compares two coils to detect a change.
Why Pilots Care
Many cockpit gauges rely on this kind of circuit to show what's happening at the wing, tank, or engine. Knowing the principle helps when troubleshooting a gauge that reads incorrectly -- the problem is often in the sensor, the wiring, or the bridge balance, not the gauge face itself.
Intuition Check
Do not read bridge as a structure you cross. Here, a bridge is an electrical comparison circuit used to measure an unknown value.
Example Sentence 1
The fuel quantity indicator uses an inductance bridge to translate float position in the tank into a reading on the cockpit gauge.
Example Sentence 2
During component testing, the inductance bridge showed the suspect inductor was outside tolerance and needed replacement.