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​ = 50 ΩR2​ = 10 ΩR3​ = ?R4​ = 60 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 50 Ω, R₂ = 10 Ω and R₄ = 60 Ω. Find the setting R3.

R1 = 50 ΩR2 = 10 ΩR4 = 60 Ω
R3 = Ω
2.Easy
+−2 VR1​ = 150 ΩR2​ = 50 ΩR3​ = ?R4​ = 600 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 150 Ω, R₂ = 50 Ω and R₄ = 600 Ω. Find the setting R3.

R1 = 150 ΩR2 = 50 ΩR4 = 600 Ω
R3 = Ω
3.Medium
+−6 VR1​ = 600 ΩR2​ = 150 ΩR3​ = 200 ΩR4​ = 400 Ωab+−Rth​ = ?

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

Vs = 6 VR1 = 600 ΩR2 = 150 ΩR3 = 200 ΩR4 = 400 Ω
Rth = Ω
4.Medium
+−15 V300 Ω300 Ω + ΔR300 Ω300 Ωab+−Vab​ = ?

A bridge has four 300 Ω arms and Vs = 15 V. The sensor R₂ increases by ΔR = 30 Ω. Find the exact output Vab in mV.

Vs = 15 VR = 300 ΩΔR = 30 Ω
Vab = mV
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 250 µε, and it must give 3.3 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

Vs = 10 VGF = 2.12εmax = 250 µεVFS = 3.3 V
G =
6.Hard
+−2.5 V120 Ω − ΔR120 Ω + ΔR120 Ω120 Ωab+−Vo​ = ?

A bridge with 120 Ω arms is excited with 2.5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2 and the strain is 1500 µε. Find the bridge output Vo in mV.

Vs = 2.5 VGF = 2ε = 1500 µε
Vo = mV

Answer key

  1. 1. R3 = 300 Ω
  2. 2. R3 = 1800 Ω
  3. 3. Rth = 253.3 Ω
  4. 4. Vab = 357.1 mV
  5. 5. G = 2491
  6. 6. Vo = 3.75 mV

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