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The Wheatstone bridge is a circuit used to measure unknown electrical resistance by balancing two legs of a bridge circuit. R_unknown = R3 × (R2/R1).
Formel
At balance: R1/R2 = R3/Rx — solve for unknown Rx
- At
- R3/Rx — solve for unknown Rx — R3/Rx — solve for unknown Rx
- R1
- R3/Rx — solve for unknown Rx — R3/Rx — solve for unknown Rx
- R2
- R3/Rx — solve for unknown Rx — R3/Rx — solve for unknown Rx
- R3
- R3 value — Variable used in the calculation
- Rx
- Rx value — Variable used in the calculation
Trinn-for-trinn guide
- 1Four resistors arranged in a diamond (bridge) configuration
- 2A galvanometer in the centre detects current imbalance
- 3At balance: R1/R2 = R3/Rx — solve for unknown Rx
Løste eksempler
Inndata
R1=100Ω, R2=200Ω, R3=150Ω
Resultat
Rx = 300Ω
Bridge balanced when R1/R2 = R3/Rx
Vanlige feil å unngå
- ✕Assuming the bridge must be exact — modern circuits use operational amplifiers for nulling
- ✕Ignoring lead resistance in precision measurements
Ofte stilte spørsmål
What is a Wheatstone bridge used for?
Precision measurement of resistance, strain gauges, temperature sensors (RTDs), and load cells.
What happens when the bridge is balanced?
No current flows through the galvanometer. The voltage across it is zero.
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