单词 | Wheatstone bridge |
释义 | Wheatstone bridge An electrical circuit for measuring the value of a resistance. In the illustration, R1 is a resistance of unknown value, R2 is a fixed resistance of known value, R3 and R4 are variable resistances with known values. When no current flows between A and B the bridge is said to be balanced, the galvanometer registers no deflection, and R1/R2 = R3/R4 . R1 can therefore be calculated. The Wheatstone bridge is used in various forms. In the metre bridge , a wire 1 metre long of uniform resistance is attached to the top of a board alongside a metre rule. A sliding contact is run along the wire, which corresponds to R3 and R4 , until the galvanometer registers zero. Most practical forms use one or more rotary rheostats to provide the variation. The device was popularized though not invented by Sir Charles Wheatstone.![]() Wheatstone bridge |
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