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​ = 800 ΩR3​ = ?R4​ = 300 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 80 Ω, R₂ = 800 Ω and R₄ = 300 Ω. Find the setting R3.

R1 = 80 ΩR2 = 800 ΩR4 = 300 Ω
R3 = Ω
2.Easy
+−10 VR1​ = 10 ΩR2​ = 200 ΩR3​ = 50 ΩR4​ = 50 Ωab+−Vab​ = ?

Find the open-circuit output voltage Vab = Va − Vb of the bridge shown, with Vs = 10 V.

Vs = 10 VR1 = 10 ΩR2 = 200 ΩR3 = 50 ΩR4 = 50 Ω
Vab = V
3.Medium
+−9 V330 Ω330 Ω + ΔR330 Ω330 Ωab+−214.3 mV

A bridge with four 330 Ω arms is supplied with 9 V. When the sensor R₂ changes, the output reads Vab = 214.3 mV. Find the exact change ΔR of R₂.

Vs = 9 VR = 330 ΩVab = 214.3 mV
ΔR = Ω
4.Medium
+−5 VR1​ = 10 ΩR2​ = 120 ΩR3​ = 1000 ΩR4​ = 300 ΩabGRg​ = 100 Ω

A galvanometer with a resistance of 100 Ω is connected between a and b of the bridge shown (Vs = 5 V). Find the galvanometer current Ig from a to b, in µA.

Vs = 5 VR1 = 10 ΩR2 = 120 ΩR3 = 1000 ΩR4 = 300 ΩRg = 100 Ω
Ig = µA
5.Hard
+−3 V120 Ω120 Ω + ΔR120 Ω120 Ωab+−1.537 mV

A quarter bridge with one active gauge (GF = 2.05) is excited with 3 V. Under load the output reads 1.537 mV. Find the strain ε in µε.

Vs = 3 VGF = 2.05Vo = 1.537 mV
ε = µε
6.Hard
+−5 V120 Ω − ΔR120 Ω + ΔR120 Ω + ΔR120 Ω − ΔRab+−Vo​ = ?

A bridge with 120 Ω arms is excited with 5 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.05 and the strain is 800 µε. Find the bridge output Vo in mV.

Vs = 5 VGF = 2.05ε = 800 µε
Vo = mV

Answer key

  1. 1. R3 = 30 Ω
  2. 2. Vab = 4.524 V
  3. 3. ΔR = 33 Ω
  4. 4. Ig = 10181 µA
  5. 5. ε = 999.7 µε
  6. 6. Vo = 8.2 mV

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