Wheatstone Bridge
Definition
A clever circuit that measures unknown resistance by balancing — when the middle meter reads zero, the ratios match and you have your answer.
Technical definition
Four resistors in a diamond; the balance condition R₁/R₂ = R₃/R₄ gives null galvanometer current. Null methods beat direct meter accuracy.
Example
Strain gauges use Wheatstone bridges — a stretched wire's tiny resistance change unbalances the bridge, weighing trucks or sensing a touchscreen's force.
Common confusion
The bridge doesn't read a value off a dial — it measures by balancing to ZERO. The unknown is computed from the three known resistors at balance.