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
+−10 VR1​ = 100 ΩR2​ = 80 ΩR3​ = 100 ΩR4​ = 600 Ωab+−Vab​ = ?

Find the open-circuit output voltage Vab = Va − Vb of the bridge shown, with Vs = 10 V.

Vs = 10 VR1 = 100 ΩR2 = 80 ΩR3 = 100 ΩR4 = 600 Ω
Vab = V
2.Easy
5 ΩRₓBGACD35 cm

In a slide-wire (metre) bridge a known 5 Ω resistor sits in the left gap and an unknown resistor Rₓ in the right gap. The galvanometer reads zero when the jockey is 35 cm from the left end A of the 100 cm wire. Find Rx.

R = 5 Ωl = 35 cmL = 100 cm
Rx = Ω
3.Medium
+−6 V150 Ω150 Ω + ΔR150 Ω150 Ωab+−169.8 mV

A bridge with four 150 Ω arms is supplied with 6 V. When the sensor R₂ changes, the output reads Vab = 169.8 mV. Find the exact change ΔR of R₂.

Vs = 6 VR = 150 ΩVab = 169.8 mV
ΔR = Ω
4.Medium
+−6 VR1​ = 150 ΩR2​ = 50 ΩR3​ = 800 ΩR4​ = 600 ΩabGRg​ = 20 Ω

A galvanometer with a resistance of 20 Ω is connected between a and b of the bridge shown (Vs = 6 V). Find the galvanometer current Ig from a to b, in µA.

Vs = 6 VR1 = 150 ΩR2 = 50 ΩR3 = 800 ΩR4 = 600 ΩRg = 20 Ω
Ig = µA
5.Hard
+−5 V120 Ω − ΔR120 Ω + ΔR120 Ω120 Ωab+−Vo​ = ?

A bridge with 120 Ω arms is excited with 5 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 500 µε. Find the bridge output Vo in mV.

Vs = 5 VGF = 2.05ε = 500 µε
Vo = mV
6.Hard
+−10 V120 Ω − ΔR120 Ω + ΔR120 Ω120 Ωab+−Vo​ = ?

A bridge with 120 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 2.1 and the strain is 400 µε. Find the bridge output Vo in mV.

Vs = 10 VGF = 2.1ε = 400 µε
Vo = mV

Answer key

  1. 1. Vab = −4.127 V
  2. 2. Rx = 9.286 Ω
  3. 3. ΔR = 18 Ω
  4. 4. Ig = −2676 µA
  5. 5. Vo = 2.563 mV
  6. 6. Vo = 4.2 mV

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