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 = 5 V.

V_s = 5 VR₁ = 20 ΩR₂ = 1000 ΩR₃ = 60 ΩR₄ = 250 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 = 12 V.

V_s = 12 VR₁ = 20 ΩR₂ = 200 ΩR₃ = 80 ΩR₄ = 50 Ω

V_ab = V

3.Medium

A bridge has four 330 Ω arms and V_s = 2 V. The sensor R₂ increases by ΔR = 0.33 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 2 VR = 330 ΩΔR = 0.33 Ω

V_ab = mV

4.Medium

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

V_s = 6 VR₁ = 300 ΩR₂ = 250 ΩR₃ = 150 ΩR₄ = 1000 ΩR_g = 20 Ω

I_g = µA

5.Hard

A load cell (a full bridge of strain gauges) has a rated output of 2.5 mV/V at its rated load of 1000 kg. It is excited with 10 V. Find its output V_o under a load of 750 kg.

2.5 mV/VF_rated = 1000 kgV_s = 10 VF = 750 kg

V_o = mV

6.Hard

A 350 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 1.05 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2ΔR = 1.05 Ω

ε = µε

Answer key

1. V_ab = 0.8697 V
2. V_ab = 6.294 V
3. V_ab = 0.5 mV
4. I_g = −8682 µA
5. V_o = 18.75 mV
6. ε = 1500 µε

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