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​ = 600 ΩR2​ = 1000 ΩR3​ = ?R4​ = 150 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 600 Ω, R₂ = 1000 Ω and R₄ = 150 Ω. Find the setting R3.

R1 = 600 ΩR2 = 1000 ΩR4 = 150 Ω
R3 = Ω
2.Easy
+−10 VR1​ = 500 ΩR2​ = 10 ΩR3​ = 1000 ΩR4​ = 120 Ωab+−

In the bridge shown, Vs = 10 V, R₁ = 500 Ω and R₂ = 10 Ω. Find the voltage Va of node a with respect to the negative supply rail.

Vs = 10 VR1 = 500 ΩR2 = 10 ΩR3 = 1000 ΩR4 = 120 Ω
Va = V
3.Medium
+−6 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 6 V. Find the power Pg dissipated in the gauge, in mW. Self-heating limits the excitation.

Vs = 6 VR = 400 Ω
Pg = mW
4.Medium
+−3 V220 Ω220 Ω + ΔR220 Ω220 Ωab+−57.69 mV

A bridge with four 220 Ω arms is supplied with 3 V. When the sensor R₂ changes, the output reads Vab = 57.69 mV. Find the exact change ΔR of R₂.

Vs = 3 VR = 220 ΩVab = 57.69 mV
ΔR = Ω
5.Hard
+−2.5 V350 Ω − ΔR350 Ω + ΔR350 Ω350 Ωab+−Vo​ = ?

A bridge with 350 Ω arms is excited with 2.5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2 and the strain is 1500 µε. Find the bridge output Vo in mV.

Vs = 2.5 VGF = 2ε = 1500 µε
Vo = mV
6.Hard
+−10 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−7.875 mV

A quarter bridge with one active gauge (GF = 2.1) is excited with 10 V. Under load the output reads 7.875 mV. Find the strain ε in µε.

Vs = 10 VGF = 2.1Vo = 7.875 mV
ε = µε

Answer key

  1. 1. R3 = 90 Ω
  2. 2. Va = 0.1961 V
  3. 3. Pg = 22.5 mW
  4. 4. ΔR = 17.6 Ω
  5. 5. Vo = 3.75 mV
  6. 6. ε = 1500 µε

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