如何计算Wheatstone
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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).
公式
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
分步指南
- 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
例题解析
输入
R1=100Ω, R2=200Ω, R3=150Ω
结果
Rx = 300Ω
Bridge balanced when R1/R2 = R3/Rx
常见错误注意事项
- ✕Assuming the bridge must be exact — modern circuits use operational amplifiers for nulling
- ✕Ignoring lead resistance in precision measurements
常见问题
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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