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
+−15 VR1​ = 1000 ΩR2​ = 1000 ΩR3​ = ?R4​ = 120 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 1000 Ω, R₂ = 1000 Ω and R₄ = 120 Ω. Find the setting R3.

R1 = 1000 ΩR2 = 1000 ΩR4 = 120 Ω
R3 = Ω
2.Easy
+−5 VR1​ = 40 ΩR2​ = 100 ΩR3​ = ?R4​ = 10 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 40 Ω, R₂ = 100 Ω and R₄ = 10 Ω. Find the setting R3.

R1 = 40 ΩR2 = 100 ΩR4 = 10 Ω
R3 = Ω
3.Medium
+−9 V120 Ω120 Ω + ΔR120 Ω120 Ωab+−Vab​ = ?

A bridge has four 120 Ω arms and Vs = 9 V. The sensor R₂ increases by ΔR = 24 Ω. Find the exact output Vab in mV.

Vs = 9 VR = 120 ΩΔR = 24 Ω
Vab = mV
4.Medium
+−6 V300 Ω300 Ω + ΔR300 Ω300 Ωab+−Vab​ = ?

A bridge has four 300 Ω arms and Vs = 6 V. The sensor R₂ increases by ΔR = 0.75 Ω. Using the small-change approximation, find the output Vab in mV.

Vs = 6 VR = 300 ΩΔR = 0.75 Ω
Vab = mV
5.Hard
+−3 V350 Ω − ΔR350 Ω + ΔR350 Ω350 Ωab+−Vo​ = ?

A bridge with 350 Ω arms is excited with 3 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 250 µε. Find the bridge output Vo in mV.

Vs = 3 VGF = 2.12ε = 250 µε
Vo = mV
6.Hard
+−3 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−1.2 mV

A strain gauge (GF = 2) on a member with E = 210 GPa forms a quarter bridge excited with 3 V. The output reads 1.2 mV. Find the axial stress σ in MPa.

Vs = 3 VGF = 2Vo = 1.2 mVE = 210 GPa
σ = MPa

Answer key

  1. 1. R3 = 120 Ω
  2. 2. R3 = 4 Ω
  3. 3. Vab = 409.1 mV
  4. 4. Vab = 3.75 mV
  5. 5. Vo = 0.795 mV
  6. 6. σ = 168 MPa

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