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​ = 500 ΩR2​ = 60 ΩR3​ = 150 ΩR4​ = 100 Ωab+−

In the bridge shown, Vs = 2 V, R₁ = 500 Ω and R₂ = 60 Ω. Find the voltage Va of node a with respect to the negative supply rail.

Vs = 2 VR1 = 500 ΩR2 = 60 ΩR3 = 150 ΩR4 = 100 Ω
Va = V
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 V150 Ω150 Ω150 Ω150 Ωab+−

A 150 Ω strain gauge is one arm (R₂) of a bridge with four equal 150 Ω arms and an excitation of 6 V. Find the power Pg dissipated in the gauge, in mW. Self-heating limits the excitation.

Vs = 6 VR = 150 Ω
Pg = mW
4.Medium
+−10 V400 Ω400 Ω + ΔR400 Ω400 Ωab+−238.1 mV

A bridge with four 400 Ω arms is supplied with 10 V. When the sensor R₂ changes, the output reads Vab = 238.1 mV. Find the exact change ΔR of R₂.

Vs = 10 VR = 400 ΩVab = 238.1 mV
ΔR = Ω
5.Hard
+−10 V350 Ω350 Ω + ΔR350 Ω350 Ωab+−Vo​ = ?

A bridge with 350 Ω arms is excited with 10 V and has one active gauge (quarter bridge). The gauge factor is 2.1 and the strain is 200 µε. Find the bridge output Vo in mV.

Vs = 10 VGF = 2.1ε = 200 µε
Vo = mV
6.Hard
+−10 V350 Ω − ΔR350 Ω + ΔR350 Ω + ΔR350 Ω − ΔRab+−Vo​ = ?

A bridge with 350 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 200 µε. Find the bridge output Vo in mV.

Vs = 10 VGF = 2ε = 200 µε
Vo = mV

Answer key

  1. 1. Va = 0.2143 V
  2. 2. Rx = 3.333 Ω
  3. 3. Pg = 60 mW
  4. 4. ΔR = 40 Ω
  5. 5. Vo = 1.05 mV
  6. 6. Vo = 4 mV

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