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​ = 100 ΩR2​ = 60 ΩR3​ = ?R4​ = 300 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 100 Ω, R₂ = 60 Ω and R₄ = 300 Ω. Find the setting R3.

R1 = 100 ΩR2 = 60 ΩR4 = 300 Ω
R3 = Ω
2.Easy
+−15 VR1​ = 600 ΩR2​ = 150 ΩR3​ = 250 ΩR4​ = 120 Ωab+−

The bridge shown is supplied with Vs = 15 V and its output is open. Find the current Is drawn from the supply, in mA.

Vs = 15 VR1 = 600 ΩR2 = 150 ΩR3 = 250 ΩR4 = 120 Ω
Is = mA
3.Medium
+−2 V470 Ω470 Ω470 Ω470 Ωab+−

A 470 Ω strain gauge is one arm (R₂) of a bridge with four equal 470 Ω arms and an excitation of 2 V. Find the power Pg dissipated in the gauge, in mW. Self-heating limits the excitation.

Vs = 2 VR = 470 Ω
Pg = mW
4.Medium
+−6 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 6 V. Find the power Pg dissipated in the gauge, in mW. Self-heating limits the excitation.

Vs = 6 VR = 220 Ω
Pg = mW
5.Hard
+−3 V350 Ω − ΔR350 Ω + ΔR350 Ω + ΔR350 Ω − ΔRab+−Vo​ = ?

A bridge with 350 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 and the strain is 1000 µε. Find the bridge output Vo in mV.

Vs = 3 VGF = 2ε = 1000 µε
Vo = mV
6.Hard
+−3 V120 Ω120 Ω + ΔR120 Ω120 Ωab+−Vo​

A quarter bridge (one active gauge, GF = 2.1) is excited with 3 V. The largest strain to be measured is 750 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

Vs = 3 VGF = 2.1εmax = 750 µεVFS = 5 V
G =

Answer key

  1. 1. R3 = 500 Ω
  2. 2. Is = 60.54 mA
  3. 3. Pg = 2.128 mW
  4. 4. Pg = 40.91 mW
  5. 5. Vo = 6 mV
  6. 6. G = 4233

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