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​ = 300 ΩR3​ = ?R4​ = 200 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 600 Ω, R₂ = 300 Ω and R₄ = 200 Ω. Find the setting R3.

R1 = 600 ΩR2 = 300 ΩR4 = 200 Ω
R3 = Ω
2.Easy
+−10 VR1​ = 500 ΩR2​ = 40 ΩR3​ = 250 ΩR4​ = ?abG0

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 500 Ω, R₂ = 40 Ω and R₃ = 250 Ω. Find the unknown resistor R4.

R1 = 500 ΩR2 = 40 ΩR3 = 250 Ω
R4 = Ω
3.Medium
+−12 V470 Ω470 Ω + ΔR470 Ω470 Ωab+−146.3 mV

A bridge with four 470 Ω arms is supplied with 12 V. When the sensor R₂ changes, the output reads Vab = 146.3 mV. Find the exact change ΔR of R₂.

Vs = 12 VR = 470 ΩVab = 146.3 mV
ΔR = Ω
4.Medium
+−10 V220 Ω220 Ω220 Ω220 Ωab+−

A 220 Ω strain gauge is one arm (R₂) of a bridge with four equal 220 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 = 220 Ω
Pg = mW
5.Hard
+−3 V120 Ω − ΔR120 Ω + ΔR120 Ω + ΔR120 Ω − ΔRab+−Vo​ = ?

A bridge with 120 Ω arms is excited with 3 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.12 and the strain is 400 µε. Find the bridge output Vo in mV.

Vs = 3 VGF = 2.12ε = 400 µε
Vo = mV
6.Hard
+−3 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−0.375 mV

A quarter bridge with one active gauge (GF = 2) is excited with 3 V. Under load the output reads 0.375 mV. Find the strain ε in µε.

Vs = 3 VGF = 2Vo = 0.375 mV
ε = µε

Answer key

  1. 1. R3 = 400 Ω
  2. 2. R4 = 20 Ω
  3. 3. ΔR = 23.5 Ω
  4. 4. Pg = 113.6 mW
  5. 5. Vo = 2.544 mV
  6. 6. ε = 250 µε

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