Wheatstone bridge & strain gauges worksheet with answers

Free printable Wheatstone bridge & strain gauges worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy
+−12 VR1​ = 500 ΩR2​ = 250 ΩR3​ = ?R4​ = 800 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 500 Ω, R₂ = 250 Ω and R₄ = 800 Ω. Find the setting R3.

R1 = 500 ΩR2 = 250 ΩR4 = 800 Ω
R3 = Ω
2.Easy
+−5 VR1​ = 500 ΩR2​ = 100 ΩR3​ = 10 ΩR4​ = 300 Ωab+−

In the bridge shown, Vs = 5 V, R₁ = 500 Ω and R₂ = 100 Ω. Find the voltage Va of node a with respect to the negative supply rail.

Vs = 5 VR1 = 500 ΩR2 = 100 ΩR3 = 10 ΩR4 = 300 Ω
Va = V
3.Medium
+−10 V330 Ω330 Ω + ΔR330 Ω330 Ωab+−Vab​ = ?

A bridge has four 330 Ω arms and Vs = 10 V. The sensor R₂ increases by ΔR = 49.5 Ω. Find the exact output Vab in mV.

Vs = 10 VR = 330 ΩΔR = 49.5 Ω
Vab = mV
4.Medium
+−3 V470 Ω470 Ω + ΔR470 Ω470 Ωab+−Vab​ = ?

A bridge has four 470 Ω arms and Vs = 3 V. The sensor R₂ increases by ΔR = 0.47 Ω. Using the small-change approximation, find the output Vab in mV.

Vs = 3 VR = 470 ΩΔR = 0.47 Ω
Vab = mV
5.Hard
+−10 V120 Ω − ΔR120 Ω + ΔR120 Ω + ΔR120 Ω − ΔRab+−Vo​ = ?

A bridge with 120 Ω arms is excited with 10 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.12 and the strain is 600 µε. Find the bridge output Vo in mV.

Vs = 10 VGF = 2.12ε = 600 µε
Vo = mV
6.Hard
+−3 V1000 Ω1000 Ω + ΔR1000 Ω1000 Ωab+−1.8 mV

A quarter bridge with one active gauge (GF = 2) is excited with 3 V. Under load the output reads 1.8 mV. Find the strain ε in µε.

Vs = 3 VGF = 2Vo = 1.8 mV
ε = µε

Answer key

  1. 1. R3 = 1600 Ω
  2. 2. Va = 0.8333 V
  3. 3. Vab = 348.8 mV
  4. 4. Vab = 0.75 mV
  5. 5. Vo = 12.72 mV
  6. 6. ε = 1200 µε

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