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

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 12 V.

V_s = 12 VR₁ = 80 ΩR₂ = 100 ΩR₃ = 500 ΩR₄ = 200 Ω

V_ab = V

2.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 3 V.

V_s = 3 VR₁ = 250 ΩR₂ = 800 ΩR₃ = 300 ΩR₄ = 400 Ω

V_ab = V

3.Medium

A bridge with four 220 Ω arms is supplied with 12 V. When the sensor R₂ changes, the output reads V_ab = 29.85 mV. Find the exact change ΔR of R₂.

V_s = 12 VR = 220 ΩV_ab = 29.85 mV

ΔR = Ω

4.Medium

Find the Thévenin resistance R_th of the bridge shown, seen from the output terminals a and b.

V_s = 10 VR₁ = 500 ΩR₂ = 1000 ΩR₃ = 800 ΩR₄ = 250 Ω

R_th = Ω

5.Hard

A load cell (a full bridge of strain gauges) has a rated output of 1 mV/V at its rated load of 50 kg. It is excited with 10 V. Find its output V_o under a load of 30 kg.

1 mV/VF_rated = 50 kgV_s = 10 VF = 30 kg

V_o = mV

6.Hard

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 1200 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.1ε = 1200 µε

V_o = mV

Answer key

1. V_ab = 3.238 V
2. V_ab = 0.5714 V
3. ΔR = 2.2 Ω
4. R_th = 523.8 Ω
5. V_o = 6 mV
6. V_o = 6.3 mV

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