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​ = 300 ΩR2​ = 150 ΩR3​ = ?R4​ = 600 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 300 Ω, R₂ = 150 Ω and R₄ = 600 Ω. Find the setting R3.

R1 = 300 ΩR2 = 150 ΩR4 = 600 Ω
R3 = Ω
2.Easy
2 ΩRₓBGACD60 cm

In a slide-wire (metre) bridge a known 2 Ω resistor sits in the left gap and an unknown resistor Rₓ in the right gap. The galvanometer reads zero when the jockey is 60 cm from the left end A of the 100 cm wire. Find Rx.

R = 2 Ωl = 60 cmL = 100 cm
Rx = Ω
3.Medium
+−12 V330 Ω330 Ω + ΔR330 Ω330 Ωab+−Vab​ = ?

A bridge has four 330 Ω arms and Vs = 12 V. The sensor R₂ increases by ΔR = 2.64 Ω. Using the small-change approximation, find the output Vab in mV.

Vs = 12 VR = 330 ΩΔR = 2.64 Ω
Vab = mV
4.Medium
+−3 V1000 Ω1000 Ω + ΔR1000 Ω1000 Ωab+−Vab​ = ?

A bridge has four 1000 Ω arms and Vs = 3 V. The sensor R₂ increases by ΔR = 8 Ω. Using the small-change approximation, find the output Vab in mV.

Vs = 3 VR = 1000 ΩΔR = 8 Ω
Vab = mV
5.Hard
+−5 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−Vo​

A quarter bridge (one active gauge, GF = 2.05) is excited with 5 V. The largest strain to be measured is 500 µε, and it must give 3.3 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

Vs = 5 VGF = 2.05εmax = 500 µεVFS = 3.3 V
G =
6.Hard
+−10 V1000 Ω − ΔR1000 Ω + ΔR1000 Ω + ΔR1000 Ω − ΔRab+−Vo​ = ?

A bridge with 1000 Ω arms is excited with 10 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2 and the strain is 600 µε. Find the bridge output Vo in mV.

Vs = 10 VGF = 2ε = 600 µε
Vo = mV

Answer key

  1. 1. R3 = 1200 Ω
  2. 2. Rx = 1.333 Ω
  3. 3. Vab = 24 mV
  4. 4. Vab = 6 mV
  5. 5. G = 2576
  6. 6. Vo = 12 mV

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