Wheatstone Bridge Calculator
Calculate unknown resistance and bridge voltage in Wheatstone bridge circuits
Calculate Wheatstone Bridge
Fixed resistance in upper left arm
Variable resistance in lower right arm
Fixed resistance in upper right arm
Unknown Resistance (Rₓ)
Formula: Rₓ = (R₂/R₁) × R₃
Calculation: Rₓ = (0/0) × 0 = 0 Ω
Condition: Bridge is balanced when R₁/R₂ = R₃/Rₓ
Bridge Analysis
Balance Condition
0Example Calculation
Balanced Bridge Example
Given: R₁ = 6 Ω, R₂ = 9 Ω, R₃ = 4 Ω
Find: Rₓ for balanced bridge
Formula: Rₓ = (R₂/R₁) × R₃
Calculation: Rₓ = (9/6) × 4 = 6 Ω
Verification: R₁/R₂ = 6/9 = 0.667, R₃/Rₓ = 4/6 = 0.667 ✓
Unbalanced Bridge Example
Given: V = 12 V, R₁ = 100 Ω, R₂ = 200 Ω, R₃ = 150 Ω, Rₓ = 250 Ω
Formula: VG = V × (R₁/(R₁+R₂) - R₃/(R₃+Rₓ))
Calculation: VG = 12 × (100/300 - 150/400) = 12 × (0.333 - 0.375) = -0.5 V
Bridge Circuit
Classical Wheatstone bridge circuit diagram
Quick Reference
Balanced: R₁/R₂ = R₃/Rₓ
VG = 0 when bridge is balanced
Used for precise resistance measurement
Applications: strain gauges, temperature sensors
Understanding the Wheatstone Bridge
What is a Wheatstone Bridge?
The Wheatstone bridge is a fundamental electrical circuit used to measure unknown electrical resistance with high precision. It consists of four resistors arranged in a diamond (rhombus) configuration with a voltage source and a galvanometer.
Key Applications
- •Strain gauge measurements for stress and force detection
- •Temperature sensing with thermistors or RTDs
- •Pressure transducers and load cells
- •High-precision resistance measurement
Bridge Equations
Balanced Bridge:
R₁/R₂ = R₃/Rₓ
Rₓ = (R₂ × R₃)/R₁
Bridge Voltage:
VG = V × (R₁/(R₁+R₂) - R₃/(R₃+Rₓ))
Equivalent Resistance:
Req = (R₁+R₂)(R₃+Rₓ)/(R₁+R₂+R₃+Rₓ)
Note: Bridge sensitivity increases with higher supply voltage, but component heating should be considered.
Bridge Types and Configurations
| Configuration | Description | Application | Sensitivity |
|---|---|---|---|
| Quarter Bridge | One active strain gauge | Basic strain measurement | Low |
| Half Bridge | Two active strain gauges | Bending, temperature compensation | Medium |
| Full Bridge | Four active strain gauges | Load cells, pressure sensors | High |