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
+−10 VR1​ = 60 ΩR2​ = 10 ΩR3​ = 300 ΩR4​ = 40 Ωab+−Vab​ = ?

Find the open-circuit output voltage Vab = Va − Vb of the bridge shown, with Vs = 10 V.

Vs = 10 VR1 = 60 ΩR2 = 10 ΩR3 = 300 ΩR4 = 40 Ω
Vab = V
2.Easy
+−12 VR1​ = 20 ΩR2​ = 400 ΩR3​ = ?R4​ = 200 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 20 Ω, R₂ = 400 Ω and R₄ = 200 Ω. Find the setting R3.

R1 = 20 ΩR2 = 400 ΩR4 = 200 Ω
R3 = Ω
3.Medium
+−12 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−Vab​ = ?

A bridge has four 350 Ω arms and Vs = 12 V. The sensor R₂ increases by ΔR = 1.4 Ω. Using the small-change approximation, find the output Vab in mV.

Vs = 12 VR = 350 ΩΔR = 1.4 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 = 0.8 Ω. Using the small-change approximation, find the output Vab in mV.

Vs = 12 VR = 400 ΩΔR = 0.8 Ω
Vab = mV
5.Hard
+−5 V120 Ω − ΔR120 Ω + ΔR120 Ω120 Ωab+−Vo​ = ?

A bridge with 120 Ω arms is excited with 5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.12 and the strain is 600 µε. Find the bridge output Vo in mV.

Vs = 5 VGF = 2.12ε = 600 µε
Vo = mV
6.Hard
+−3 V120 Ω120 Ω + ΔR120 Ω120 Ωab+−1.8 mV

A strain gauge (GF = 2) on a member with E = 210 GPa forms a quarter bridge excited with 3 V. The output reads 1.8 mV. Find the axial stress σ in MPa.

Vs = 3 VGF = 2Vo = 1.8 mVE = 210 GPa
σ = MPa

Answer key

  1. 1. Vab = 0.2521 V
  2. 2. R3 = 10 Ω
  3. 3. Vab = 12 mV
  4. 4. Vab = 6 mV
  5. 5. Vo = 3.18 mV
  6. 6. σ = 252 MPa

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