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​ = 20 ΩR2​ = 40 ΩR3​ = 500 ΩR4​ = 250 Ωab+−

In the bridge shown, Vs = 15 V, R₁ = 20 Ω and R₂ = 40 Ω. Find the voltage Va of node a with respect to the negative supply rail.

Vs = 15 VR1 = 20 ΩR2 = 40 ΩR3 = 500 ΩR4 = 250 Ω
Va = V
2.Easy
+−3 VR1​ = 300 ΩR2​ = 100 ΩR3​ = ?R4​ = 500 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 300 Ω, R₂ = 100 Ω and R₄ = 500 Ω. Find the setting R3.

R1 = 300 ΩR2 = 100 ΩR4 = 500 Ω
R3 = Ω
3.Medium
+−10 V400 Ω400 Ω400 Ω400 Ωab+−

A 400 Ω strain gauge is one arm (R₂) of a bridge with four equal 400 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 = 400 Ω
Pg = mW
4.Medium
+−15 V300 Ω300 Ω + ΔR300 Ω300 Ωab+−288.5 mV

A bridge with four 300 Ω arms is supplied with 15 V. When the sensor R₂ changes, the output reads Vab = 288.5 mV. Find the exact change ΔR of R₂.

Vs = 15 VR = 300 ΩVab = 288.5 mV
ΔR = Ω
5.Hard
+−5 V1000 Ω − ΔR1000 Ω + ΔR1000 Ω1000 Ωab+−Vo​ = ?

A bridge with 1000 Ω arms is excited with 5 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 1200 µε. Find the bridge output Vo in mV.

Vs = 5 VGF = 2.12ε = 1200 µε
Vo = mV
6.Hard
+−5 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−0.641 mV

A quarter bridge with one active gauge (GF = 2.05) is excited with 5 V. Under load the output reads 0.641 mV. Find the strain ε in µε.

Vs = 5 VGF = 2.05Vo = 0.641 mV
ε = µε

Answer key

  1. 1. Va = 10 V
  2. 2. R3 = 1500 Ω
  3. 3. Pg = 62.5 mW
  4. 4. ΔR = 24 Ω
  5. 5. Vo = 6.36 mV
  6. 6. ε = 250.1 µε

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