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​ = 150 ΩR2​ = 800 ΩR3​ = ?R4​ = 600 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 150 Ω, R₂ = 800 Ω and R₄ = 600 Ω. Find the setting R3.

R1 = 150 ΩR2 = 800 ΩR4 = 600 Ω
R3 = Ω
2.Easy
+−6 VR1​ = 300 ΩR2​ = 300 ΩR3​ = 150 ΩR4​ = 150 Ωab+−

In the bridge shown, Vs = 6 V, R₁ = 300 Ω and R₂ = 300 Ω. Find the voltage Va of node a with respect to the negative supply rail.

Vs = 6 VR1 = 300 ΩR2 = 300 ΩR3 = 150 ΩR4 = 150 Ω
Va = V
3.Medium
+−15 VR1​ = 60 ΩR2​ = 60 ΩR3​ = 150 ΩR4​ = 100 ΩabGRg​ = 50 Ω

A galvanometer with a resistance of 50 Ω is connected between a and b of the bridge shown (Vs = 15 V). Find the galvanometer current Ig from a to b, in µA.

Vs = 15 VR1 = 60 ΩR2 = 60 ΩR3 = 150 ΩR4 = 100 ΩRg = 50 Ω
Ig = µA
4.Medium
+−5 V470 Ω470 Ω + ΔR470 Ω470 Ωab+−60.98 mV

A bridge with four 470 Ω arms is supplied with 5 V. When the sensor R₂ changes, the output reads Vab = 60.98 mV. Find the exact change ΔR of R₂.

Vs = 5 VR = 470 ΩVab = 60.98 mV
ΔR = Ω
5.Hard
+−3 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−0.922 mV

A strain gauge (GF = 2.05) on a member with E = 70 GPa forms a quarter bridge excited with 3 V. The output reads 0.922 mV. Find the axial stress σ in MPa.

Vs = 3 VGF = 2.05Vo = 0.922 mVE = 70 GPa
σ = MPa
6.Hard
+−2.5 V350 Ω − ΔR350 Ω + ΔR350 Ω + ΔR350 Ω − ΔRab+−Vo​ = ?

A bridge with 350 Ω arms is excited with 2.5 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.1 and the strain is 250 µε. Find the bridge output Vo in mV.

Vs = 2.5 VGF = 2.1ε = 250 µε
Vo = mV

Answer key

  1. 1. R3 = 112.5 Ω
  2. 2. Va = 3 V
  3. 3. Ig = 10714 µA
  4. 4. ΔR = 23.5 Ω
  5. 5. σ = 41.98 MPa
  6. 6. Vo = 1.313 mV

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