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
+−5 VR1​ = 400 ΩR2​ = 800 ΩR3​ = ?R4​ = 600 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 400 Ω, R₂ = 800 Ω and R₄ = 600 Ω. Find the setting R3.

R1 = 400 ΩR2 = 800 ΩR4 = 600 Ω
R3 = Ω
2.Easy
10 ΩRₓBGACD75 cm

In a slide-wire (metre) bridge a known 10 Ω resistor sits in the left gap and an unknown resistor Rₓ in the right gap. The galvanometer reads zero when the jockey is 75 cm from the left end A of the 100 cm wire. Find Rx.

R = 10 Ωl = 75 cmL = 100 cm
Rx = Ω
3.Medium
+−6 V200 Ω200 Ω + ΔR200 Ω200 Ωab+−Vab​ = ?

A bridge has four 200 Ω arms and Vs = 6 V. The sensor R₂ increases by ΔR = 30 Ω. Find the exact output Vab in mV.

Vs = 6 VR = 200 ΩΔR = 30 Ω
Vab = mV
4.Medium
+−5 V330 Ω330 Ω330 Ω330 Ωab+−

A 330 Ω strain gauge is one arm (R₂) of a bridge with four equal 330 Ω arms and an excitation of 5 V. Find the power Pg dissipated in the gauge, in mW. Self-heating limits the excitation.

Vs = 5 VR = 330 Ω
Pg = mW
5.Hard
+−3 V350 Ω − ΔR350 Ω + ΔR350 Ω350 Ωab+−Vo​ = ?

A bridge with 350 Ω arms is excited with 3 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.05 and the strain is 1500 µε. Find the bridge output Vo in mV.

Vs = 3 VGF = 2.05ε = 1500 µε
Vo = mV
6.Hard
+−10 V1000 Ω − ΔR1000 Ω + ΔR1000 Ω1000 Ωab+−Vo​ = ?

A bridge with 1000 Ω arms is excited with 10 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 1200 µε. Find the bridge output Vo in mV.

Vs = 10 VGF = 2ε = 1200 µε
Vo = mV

Answer key

  1. 1. R3 = 300 Ω
  2. 2. Rx = 3.333 Ω
  3. 3. Vab = 209.3 mV
  4. 4. Pg = 18.94 mW
  5. 5. Vo = 4.612 mV
  6. 6. Vo = 12 mV

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