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
+−5 VR1​ = 60 ΩR2​ = 50 ΩR3​ = ?R4​ = 60 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 60 Ω, R₂ = 50 Ω and R₄ = 60 Ω. Find the setting R3.

R1 = 60 ΩR2 = 50 ΩR4 = 60 Ω
R3 = Ω
2.Easy
+−2 VR1​ = 1000 ΩR2​ = 600 ΩR3​ = 10 ΩR4​ = 10 Ωab+−Vab​ = ?

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

Vs = 2 VR1 = 1000 ΩR2 = 600 ΩR3 = 10 ΩR4 = 10 Ω
Vab = V
3.Medium
+−12 VR1​ = 80 ΩR2​ = 300 ΩR3​ = 400 ΩR4​ = 120 Ωab+−Rth​ = ?

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

Vs = 12 VR1 = 80 ΩR2 = 300 ΩR3 = 400 ΩR4 = 120 Ω
Rth = Ω
4.Medium
+−2 V220 Ω220 Ω + ΔR220 Ω220 Ωab+−9.9 mV

A bridge with four 220 Ω arms is supplied with 2 V. When the sensor R₂ changes, the output reads Vab = 9.9 mV. Find the exact change ΔR of R₂.

Vs = 2 VR = 220 ΩVab = 9.9 mV
ΔR = Ω
5.Hard
+−3 V120 Ω120 Ω + ΔR120 Ω120 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
6.Hard
+−10 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−Vo​ = ?

A bridge with 350 Ω arms is excited with 10 V and has one active gauge (quarter bridge). The gauge factor is 2.05 and the strain is 750 µε. Find the bridge output Vo in mV.

Vs = 10 VGF = 2.05ε = 750 µε
Vo = mV

Answer key

  1. 1. R3 = 72 Ω
  2. 2. Vab = −0.25 V
  3. 3. Rth = 155.5 Ω
  4. 4. ΔR = 4.4 Ω
  5. 5. ε = 1200 µε
  6. 6. Vo = 3.844 mV

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