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​ = 80 ΩR2​ = 200 ΩR3​ = 100 ΩR4​ = 200 Ωab+−Vab​ = ?

Find the open-circuit output voltage Vab = Va − Vb of the bridge shown, with Vs = 15 V.

Vs = 15 VR1 = 80 ΩR2 = 200 ΩR3 = 100 ΩR4 = 200 Ω
Vab = V
2.Easy
+−9 VR1​ = 300 ΩR2​ = 200 ΩR3​ = ?R4​ = 800 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 300 Ω, R₂ = 200 Ω and R₄ = 800 Ω. Find the setting R3.

R1 = 300 ΩR2 = 200 ΩR4 = 800 Ω
R3 = Ω
3.Medium
+−10 V300 Ω300 Ω300 Ω300 Ωab+−

A 300 Ω strain gauge is one arm (R₂) of a bridge with four equal 300 Ω arms and an excitation of 10 V. Find the power Pg dissipated in the gauge, in mW. Self-heating limits the excitation.

Vs = 10 VR = 300 Ω
Pg = mW
4.Medium
+−9 V100 Ω100 Ω + ΔR100 Ω100 Ωab+−173.1 mV

A bridge with four 100 Ω arms is supplied with 9 V. When the sensor R₂ changes, the output reads Vab = 173.1 mV. Find the exact change ΔR of R₂.

Vs = 9 VR = 100 ΩVab = 173.1 mV
ΔR = Ω
5.Hard
+−3 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−Vo​ = ?

A bridge with 350 Ω arms is excited with 3 V and has one active gauge (quarter bridge). The gauge factor is 2.12 and the strain is 1000 µε. Find the bridge output Vo in mV.

Vs = 3 VGF = 2.12ε = 1000 µε
Vo = mV
6.Hard
+−10 V120 Ω − ΔR120 Ω + ΔR120 Ω120 Ωab+−Vo​ = ?

A bridge with 120 Ω arms is excited with 10 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.05 and the strain is 250 µε. Find the bridge output Vo in mV.

Vs = 10 VGF = 2.05ε = 250 µε
Vo = mV

Answer key

  1. 1. Vab = 0.7143 V
  2. 2. R3 = 1200 Ω
  3. 3. Pg = 83.33 mW
  4. 4. ΔR = 8 Ω
  5. 5. Vo = 1.59 mV
  6. 6. Vo = 2.563 mV

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