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
+−12 VR1​ = 800 ΩR2​ = 400 ΩR3​ = ?R4​ = 600 ΩabG0

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

R1 = 800 ΩR2 = 400 ΩR4 = 600 Ω
R3 = Ω
2.Easy
+−3 VR1​ = 800 ΩR2​ = 200 ΩR3​ = 50 ΩR4​ = ?abG0

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 800 Ω, R₂ = 200 Ω and R₃ = 50 Ω. Find the unknown resistor R4.

R1 = 800 ΩR2 = 200 ΩR3 = 50 Ω
R4 = Ω
3.Medium
+−15 V330 Ω330 Ω + ΔR330 Ω330 Ωab+−74.26 mV

A bridge with four 330 Ω arms is supplied with 15 V. When the sensor R₂ changes, the output reads Vab = 74.26 mV. Find the exact change ΔR of R₂.

Vs = 15 VR = 330 ΩVab = 74.26 mV
ΔR = Ω
4.Medium
+−5 V300 Ω300 Ω300 Ω300 Ωab+−

A 300 Ω strain gauge is one arm (R₂) of a bridge with four equal 300 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 = 300 Ω
Pg = mW
5.Hard
+−3 V1000 Ω1000 Ω + ΔR1000 Ω1000 Ωab+−Vo​

A quarter bridge (one active gauge, GF = 2.05) is excited with 3 V. The largest strain to be measured is 250 µε, and it must give 10 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

Vs = 3 VGF = 2.05εmax = 250 µεVFS = 10 V
G =
6.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 1000 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 = 1000 µεVFS = 3.3 V
G =

Answer key

  1. 1. R3 = 1200 Ω
  2. 2. R4 = 12.5 Ω
  3. 3. ΔR = 6.6 Ω
  4. 4. Pg = 20.83 mW
  5. 5. G = 26016
  6. 6. G = 1288

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