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
+−2 VR1​ = 150 ΩR2​ = 500 ΩR3​ = 100 ΩR4​ = 500 Ωab+−

The bridge shown is supplied with Vs = 2 V and its output is open. Find the current Is drawn from the supply, in mA.

Vs = 2 VR1 = 150 ΩR2 = 500 ΩR3 = 100 ΩR4 = 500 Ω
Is = mA
2.Easy
+−6 VR1​ = 80 ΩR2​ = 200 ΩR3​ = ?R4​ = 600 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 80 Ω, R₂ = 200 Ω and R₄ = 600 Ω. Find the setting R3.

R1 = 80 ΩR2 = 200 ΩR4 = 600 Ω
R3 = Ω
3.Medium
+−15 V300 Ω300 Ω + ΔR300 Ω300 Ωab+−Vab​ = ?

A bridge has four 300 Ω arms and Vs = 15 V. The sensor R₂ increases by ΔR = 2.4 Ω. Using the small-change approximation, find the output Vab in mV.

Vs = 15 VR = 300 ΩΔR = 2.4 Ω
Vab = mV
4.Medium
+−12 V400 Ω400 Ω + ΔR400 Ω400 Ωab+−Vab​ = ?

A bridge has four 400 Ω arms and Vs = 12 V. The sensor R₂ increases by ΔR = 80 Ω. Find the exact output Vab in mV.

Vs = 12 VR = 400 ΩΔR = 80 Ω
Vab = mV
5.Hard
+−5 V120 Ω120 Ω + ΔR120 Ω120 Ωab+−Vo​ = ?

A bridge with 120 Ω arms is excited with 5 V and has one active gauge (quarter bridge). The gauge factor is 2 and the strain is 1000 µε. Find the bridge output Vo in mV.

Vs = 5 VGF = 2ε = 1000 µε
Vo = mV
6.Hard
+−2.5 V1000 Ω − ΔR1000 Ω + ΔR1000 Ω1000 Ωab+−Vo​ = ?

A bridge with 1000 Ω arms is excited with 2.5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.1 and the strain is 1000 µε. Find the bridge output Vo in mV.

Vs = 2.5 VGF = 2.1ε = 1000 µε
Vo = mV

Answer key

  1. 1. Is = 6.41 mA
  2. 2. R3 = 240 Ω
  3. 3. Vab = 30 mV
  4. 4. Vab = 545.5 mV
  5. 5. Vo = 2.5 mV
  6. 6. Vo = 2.625 mV

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