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​ = 10 ΩR2​ = 150 ΩR3​ = 150 ΩR4​ = 50 Ωab+−

In the bridge shown, Vs = 3 V, R₁ = 10 Ω and R₂ = 150 Ω. Find the voltage Va of node a with respect to the negative supply rail.

Vs = 3 VR1 = 10 ΩR2 = 150 ΩR3 = 150 ΩR4 = 50 Ω
Va = V
2.Easy
+−9 VR1​ = 120 ΩR2​ = 20 ΩR3​ = ?R4​ = 300 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 120 Ω, R₂ = 20 Ω and R₄ = 300 Ω. Find the setting R3.

R1 = 120 ΩR2 = 20 ΩR4 = 300 Ω
R3 = Ω
3.Medium
+−3 V220 Ω220 Ω + ΔR220 Ω220 Ωab+−7.46 mV

A bridge with four 220 Ω arms is supplied with 3 V. When the sensor R₂ changes, the output reads Vab = 7.46 mV. Find the exact change ΔR of R₂.

Vs = 3 VR = 220 ΩVab = 7.46 mV
ΔR = Ω
4.Medium
+−9 V120 Ω120 Ω + ΔR120 Ω120 Ωab+−173.1 mV

A bridge with four 120 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 = 120 ΩVab = 173.1 mV
ΔR = Ω
5.Hard
+−10 V1000 Ω1000 Ω + ΔR1000 Ω1000 Ωab+−2.625 mV

A quarter bridge with one active gauge (GF = 2.1) is excited with 10 V. Under load the output reads 2.625 mV. Find the strain ε in µε.

Vs = 10 VGF = 2.1Vo = 2.625 mV
ε = µε
6.Hard
+−3 V1000 Ω − ΔR1000 Ω + ΔR1000 Ω + ΔR1000 Ω − ΔRab+−Vo​ = ?

A bridge with 1000 Ω arms is excited with 3 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.1 and the strain is 250 µε. Find the bridge output Vo in mV.

Vs = 3 VGF = 2.1ε = 250 µε
Vo = mV

Answer key

  1. 1. Va = 2.813 V
  2. 2. R3 = 1800 Ω
  3. 3. ΔR = 2.199 Ω
  4. 4. ΔR = 9.6 Ω
  5. 5. ε = 500 µε
  6. 6. Vo = 1.575 mV

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