Wheatstone Bridge
Compute unknown resistance Rx at balance from known arms R1/R2/R3.
Inputs
Formula
Rx = R2·R3/R1
At balance the galvanometer reads zero; high precision.
Fundamentals
Compute unknown resistance Rx at balance from known arms R1/R2/R3.
This tool computes Wheatstone Bridge from the formula: Rx = R2·R3/R1
History
Design theory of gears, threads and bearings matured with machine tools and standardisation (AGMA, ISO) since the Industrial Revolution.
Engineering applications
Used for transmission design, joint strength checks and component selection.
Glossary
| Resistor R1 | Input parameter |
| Resistor R2 | Input parameter |
| Resistor R3 | Input parameter |
| Unknown Rx | Output result |
How to use
- Fill in Resistor R1, Resistor R2, Resistor R3 in the Inputs section (watch the unit on each field).
- Click Calculate; the tool evaluates the formula shown above.
- Read Unknown Rx in the results area.
Formula · Worked Example · Knowledge
Formula
核心计算关系：Rx = R2·R3/R1
输入变量：
- Resistor R1
R1— Ω - Resistor R2
R2— Ω - Resistor R3
R3— Ω
输出结果：
- Unknown Rx
Rx— Ω
假设/适用：Gearing/thread formulas assume standard, zero-backlash mounting; include error & load factors K_A.
Worked Example
根据公式 Rx = R2·R3/R1，取 Resistor R1 = 100 Ω；Resistor R2 = 100 Ω；Resistor R3 = 220 Ω。
代入计算得：Unknown Rx = 220 Ω。
Key Points
- Gearing/thread formulas assume standard, zero-backlash mounting; include error & load factors K_A.
- Compare stress with allowable stress and keep a safety factor (≥1.5, ≥2 for critical parts).
- For high speed/load also check lubrication, heat and fatigue life, not just static strength.
Parameters
Inputs
| Parameter | Symbol | Unit | Default |
|---|---|---|---|
| Resistor R1 (Ω) | R1 | Ω | 100 |
| Resistor R2 (Ω) | R2 | Ω | 100 |
| Resistor R3 (Ω) | R3 | Ω | 220 |
Outputs
| Result | Symbol | Unit |
|---|---|---|
| Unknown Rx | Rx | Ω |
Applications
- Common engineering use cases
FAQ
What formula does this tool use?
This tool computes per ISO / AGMA / ASME standard formulas: Rx = R2·R3/R1
How accurate are the results?
Results match input precision, based on SI units and common engineering approximations; for critical duty re-check with a safety factor.
Where is it used?
Common engineering use cases