Electrical & Computer
Wheatstone Bridge Lab
A Wheatstone bridge is two voltage dividers compared against each other, and its superpower is the balanced null: when R1·R4 = R2·R3 the output is exactly zero. That zero baseline is what lets the bridge resolve the minuscule resistance change of a strain gauge. Here one arm is an active gauge — apply strain ε and its resistance shifts by ΔR/R = GF·ε (GF is the gauge factor), unbalancing the bridge and deflecting the output meter. The readout shows the exact differential output Vout = Vex·(R2/(R1+R2) − R4/(R3+R4)) alongside the textbook quarter-bridge approximation Vout ≈ Vex·GF·ε/4, and how closely they agree. Tension reads positive, compression negative — the principle behind load cells, pressure sensors and scales.
1.25 mV
Output Vout
1.25 mV
Approx Vex·GF·ε/4
0.100 %
Gauge ΔR/R
0.05 %
Approx error
120 Ω
Nominal R
120.12 Ω
Active R2
One arm (R2*) is the strain gauge. At zero strain the bridge is balanced and Vout = 0 — the trick that lets it resolve a gauge's tiny ΔR/R = GF·ε. Strain unbalances it, giving Vout ≈ Vex·GF·ε/4 (the quarter-bridge formula). Tension reads positive, compression negative.
How to use this simulation
A Wheatstone bridge is two voltage dividers compared against each other, and its superpower is the balanced null: when R1·R4 = R2·R3 the output is exactly zero. That zero baseline is what lets the bridge resolve the minuscule resistance change of a strain gauge. Here one arm is an active gauge — apply strain ε and its resistance shifts by ΔR/R = GF·ε (GF is the gauge factor), unbalancing the bridge and deflecting the output meter. The readout shows the exact differential output Vout = Vex·(R2/(R1+R2) − R4/(R3+R4)) alongside the textbook quarter-bridge approximation Vout ≈ Vex·GF·ε/4, and how closely they agree. Tension reads positive, compression negative — the principle behind load cells, pressure sensors and scales.
Everything runs in your browser — no sign-up, no download. Change a value and the result updates instantly, so you can build a feel for how each input shapes the outcome. It pairs with Crameleon's practice exams and step sheets when you want to go from intuition to working the problems.