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
+−6 VR1​ = 250 ΩR2​ = 100 ΩR3​ = ?R4​ = 40 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 250 Ω, R₂ = 100 Ω and R₄ = 40 Ω. Find the setting R3.

R1 = 250 ΩR2 = 100 ΩR4 = 40 Ω
R3 = Ω
2.Easy
+−9 VR1​ = 600 ΩR2​ = 400 ΩR3​ = ?R4​ = 20 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 600 Ω, R₂ = 400 Ω and R₄ = 20 Ω. Find the setting R3.

R1 = 600 ΩR2 = 400 ΩR4 = 20 Ω
R3 = Ω
3.Medium
+−10 V100 Ω100 Ω + ΔR100 Ω100 Ωab+−Vab​ = ?

A bridge has four 100 Ω arms and Vs = 10 V. The sensor R₂ increases by ΔR = 5 Ω. Find the exact output Vab in mV.

Vs = 10 VR = 100 ΩΔR = 5 Ω
Vab = mV
4.Medium
+−12 V100 Ω100 Ω + ΔR100 Ω100 Ωab+−339.6 mV

A bridge with four 100 Ω arms is supplied with 12 V. When the sensor R₂ changes, the output reads Vab = 339.6 mV. Find the exact change ΔR of R₂.

Vs = 12 VR = 100 ΩVab = 339.6 mV
ΔR = Ω
5.Hard
+−10 V120 Ω120 Ω + ΔR120 Ω120 Ωab+−Vo​

A quarter bridge (one active gauge, GF = 2.12) is excited with 10 V. The largest strain to be measured is 1000 µε, and it must give 2.5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

Vs = 10 VGF = 2.12εmax = 1000 µεVFS = 2.5 V
G =
6.Hard
+−2.5 V120 Ω120 Ω + ΔR120 Ω120 Ωab+−Vo​ = ?

A bridge with 120 Ω arms is excited with 2.5 V and has one active gauge (quarter bridge). The gauge factor is 2.05 and the strain is 500 µε. Find the bridge output Vo in mV.

Vs = 2.5 VGF = 2.05ε = 500 µε
Vo = mV

Answer key

  1. 1. R3 = 100 Ω
  2. 2. R3 = 30 Ω
  3. 3. Vab = 122 mV
  4. 4. ΔR = 12 Ω
  5. 5. G = 471.7
  6. 6. Vo = 0.6406 mV

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