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
+−2 VR1​ = 800 ΩR2​ = 600 ΩR3​ = 120 ΩR4​ = 150 Ωab+−

In the bridge shown, Vs = 2 V, R₁ = 800 Ω and R₂ = 600 Ω. Find the voltage Va of node a with respect to the negative supply rail.

Vs = 2 VR1 = 800 ΩR2 = 600 ΩR3 = 120 ΩR4 = 150 Ω
Va = V
2.Easy
+−5 VR1​ = 40 ΩR2​ = 250 ΩR3​ = ?R4​ = 20 ΩabG0

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 40 Ω, R₂ = 250 Ω and R₄ = 20 Ω. Find the setting R3.

R1 = 40 ΩR2 = 250 ΩR4 = 20 Ω
R3 = Ω
3.Medium
+−10 V120 Ω120 Ω120 Ω120 Ωab+−

A 120 Ω strain gauge is one arm (R₂) of a bridge with four equal 120 Ω arms and an excitation of 10 V. Find the power Pg dissipated in the gauge, in mW. Self-heating limits the excitation.

Vs = 10 VR = 120 Ω
Pg = mW
4.Medium
+−10 V470 Ω470 Ω + ΔR470 Ω470 Ωab+−98.04 mV

A bridge with four 470 Ω arms is supplied with 10 V. When the sensor R₂ changes, the output reads Vab = 98.04 mV. Find the exact change ΔR of R₂.

Vs = 10 VR = 470 ΩVab = 98.04 mV
ΔR = Ω
5.Hard
+−2.5 V120 Ω − ΔR120 Ω + ΔR120 Ω + ΔR120 Ω − ΔRab+−Vo​ = ?

A bridge with 120 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 and the strain is 1500 µε. Find the bridge output Vo in mV.

Vs = 2.5 VGF = 2ε = 1500 µε
Vo = mV
6.Hard
+−2.5 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−Vo​

A quarter bridge (one active gauge, GF = 2.05) is excited with 2.5 V. The largest strain to be measured is 1000 µε, and it must give 3.3 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

Vs = 2.5 VGF = 2.05εmax = 1000 µεVFS = 3.3 V
G =

Answer key

  1. 1. Va = 0.8571 V
  2. 2. R3 = 3.2 Ω
  3. 3. Pg = 208.3 mW
  4. 4. ΔR = 18.8 Ω
  5. 5. Vo = 7.5 mV
  6. 6. G = 2576

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