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
+−3 VR1​ = 400 ΩR2​ = 150 ΩR3​ = 60 ΩR4​ = 400 Ωab+−

In the bridge shown, Vs = 3 V, R₁ = 400 Ω and R₂ = 150 Ω. Find the voltage Va of node a with respect to the negative supply rail.

Vs = 3 VR1 = 400 ΩR2 = 150 ΩR3 = 60 ΩR4 = 400 Ω
Va = V
2.Easy
+−2 VR1​ = 1000 ΩR2​ = 200 ΩR3​ = 10 ΩR4​ = 20 Ωab+−Vab​ = ?

Find the open-circuit output voltage Vab = Va − Vb of the bridge shown, with Vs = 2 V.

Vs = 2 VR1 = 1000 ΩR2 = 200 ΩR3 = 10 ΩR4 = 20 Ω
Vab = V
3.Medium
+−6 VR1​ = 40 ΩR2​ = 20 ΩR3​ = 10 ΩR4​ = 500 Ωab+−Rth​ = ?

Find the Thévenin resistance Rth of the bridge shown, seen from the output terminals a and b.

Vs = 6 VR1 = 40 ΩR2 = 20 ΩR3 = 10 ΩR4 = 500 Ω
Rth = Ω
4.Medium
+−3 V300 Ω300 Ω + ΔR300 Ω300 Ωab+−Vab​ = ?

A bridge has four 300 Ω arms and Vs = 3 V. The sensor R₂ increases by ΔR = 30 Ω. Find the exact output Vab in mV.

Vs = 3 VR = 300 ΩΔR = 30 Ω
Vab = mV
5.Hard
+−10 V120 Ω120 Ω + ΔR120 Ω120 Ωab+−3.18 mV

A quarter bridge with one active gauge (GF = 2.12) is excited with 10 V. Under load the output reads 3.18 mV. Find the strain ε in µε.

Vs = 10 VGF = 2.12Vo = 3.18 mV
ε = µε
6.Hard
+−3 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−1.23 mV

A strain gauge (GF = 2.05) on a member with E = 200 GPa forms a quarter bridge excited with 3 V. The output reads 1.23 mV. Find the axial stress σ in MPa.

Vs = 3 VGF = 2.05Vo = 1.23 mVE = 200 GPa
σ = MPa

Answer key

  1. 1. Va = 0.8182 V
  2. 2. Vab = −1 V
  3. 3. Rth = 23.14 Ω
  4. 4. Vab = 71.43 mV
  5. 5. ε = 600 µε
  6. 6. σ = 160 MPa

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