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
+−5 VR1​ = 80 ΩR2​ = 250 ΩR3​ = ?R4​ = 50 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 80 Ω, R₂ = 250 Ω and R₄ = 50 Ω. Find the setting R3.

R1 = 80 ΩR2 = 250 ΩR4 = 50 Ω
R3 = Ω
2.Easy
+−9 VR1​ = 150 ΩR2​ = 150 ΩR3​ = ?R4​ = 20 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 150 Ω, R₂ = 150 Ω and R₄ = 20 Ω. Find the setting R3.

R1 = 150 ΩR2 = 150 ΩR4 = 20 Ω
R3 = Ω
3.Medium
+−10 V300 Ω300 Ω300 Ω300 Ωab+−

A 300 Ω strain gauge is one arm (R₂) of a bridge with four equal 300 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 = 300 Ω
Pg = mW
4.Medium
+−5 VR1​ = 60 ΩR2​ = 60 ΩR3​ = 120 ΩR4​ = 500 Ωab+−Rth​ = ?

Find the Thévenin resistance Rth of the bridge shown, seen from the output terminals a and b.

Vs = 5 VR1 = 60 ΩR2 = 60 ΩR3 = 120 ΩR4 = 500 Ω
Rth = Ω
5.Hard
+−V1000 Ω1000 Ω + ΔR1000 Ω1000 Ωab+−

A 1000 Ω strain gauge with gauge factor 2.05 is bonded to a steel bar. Under load its resistance rises by 1.64 Ω. Find the strain ε in microstrain (µε).

R = 1000 ΩGF = 2.05ΔR = 1.64 Ω
ε = µε
6.Hard
+−V350 Ω350 Ω + ΔR350 Ω350 Ωab+−

A 350 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 0.525 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2ΔR = 0.525 Ω
ε = µε

Answer key

  1. 1. R3 = 16 Ω
  2. 2. R3 = 20 Ω
  3. 3. Pg = 83.33 mW
  4. 4. Rth = 126.8 Ω
  5. 5. ε = 800 µε
  6. 6. ε = 750 µε

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