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
+−9 VR1​ = 300 ΩR2​ = 1000 ΩR3​ = ?R4​ = 20 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 300 Ω, R₂ = 1000 Ω and R₄ = 20 Ω. Find the setting R3.

R1 = 300 ΩR2 = 1000 ΩR4 = 20 Ω
R3 = Ω
2.Easy
+−6 VR1​ = 100 ΩR2​ = 400 ΩR3​ = ?R4​ = 10 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 100 Ω, R₂ = 400 Ω and R₄ = 10 Ω. Find the setting R3.

R1 = 100 ΩR2 = 400 ΩR4 = 10 Ω
R3 = Ω
3.Medium
+−9 V300 Ω300 Ω + ΔR300 Ω300 Ωab+−22.39 mV

A bridge with four 300 Ω arms is supplied with 9 V. When the sensor R₂ changes, the output reads Vab = 22.39 mV. Find the exact change ΔR of R₂.

Vs = 9 VR = 300 ΩVab = 22.39 mV
ΔR = Ω
4.Medium
+−15 V330 Ω330 Ω + ΔR330 Ω330 Ωab+−Vab​ = ?

A bridge has four 330 Ω arms and Vs = 15 V. The sensor R₂ increases by ΔR = 66 Ω. Find the exact output Vab in mV.

Vs = 15 VR = 330 ΩΔR = 66 Ω
Vab = mV
5.Hard
+−12 V120 Ω − ΔR120 Ω + ΔR120 Ω + ΔR120 Ω − ΔRab+−Vo​ = ?

A load cell (a full bridge of strain gauges) has a rated output of 2.5 mV/V at its rated load of 100 kg. It is excited with 12 V. Find its output Vo under a load of 60 kg.

2.5 mV/VFrated = 100 kgVs = 12 VF = 60 kg
Vo = mV
6.Hard
+−3 V1000 Ω1000 Ω + ΔR1000 Ω1000 Ωab+−Vo​ = ?

A bridge with 1000 Ω arms is excited with 3 V and has one active gauge (quarter bridge). The gauge factor is 2 and the strain is 1200 µε. Find the bridge output Vo in mV.

Vs = 3 VGF = 2ε = 1200 µε
Vo = mV

Answer key

  1. 1. R3 = 6 Ω
  2. 2. R3 = 2.5 Ω
  3. 3. ΔR = 3 Ω
  4. 4. Vab = 681.8 mV
  5. 5. Vo = 18 mV
  6. 6. Vo = 1.8 mV

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