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 = 9 V.

V_s = 9 VR₁ = 100 ΩR₂ = 120 ΩR₃ = 60 ΩR₄ = 20 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 = 15 V.

V_s = 15 VR₁ = 80 ΩR₂ = 120 ΩR₃ = 150 ΩR₄ = 80 Ω

V_ab = V

3.Medium

A bridge has four 100 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 0.2 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 9 VR = 100 ΩΔR = 0.2 Ω

V_ab = mV

4.Medium

A bridge has four 500 Ω arms and V_s = 15 V. The sensor R₂ increases by ΔR = 5 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 15 VR = 500 ΩΔR = 5 Ω

V_ab = mV

5.Hard

A 120 Ω strain gauge with gauge factor 2.1 is bonded to a steel bar. Under load its resistance rises by 0.252 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2.1ΔR = 0.252 Ω

ε = µε

6.Hard

A strain gauge (GF = 2) on a member with E = 110 GPa forms a quarter bridge excited with 10 V. The output reads 3 mV. Find the axial stress σ in MPa.

V_s = 10 VGF = 2V_o = 3 mVE = 110 GPa

σ = MPa

Answer key

1. V_ab = 2.659 V
2. V_ab = 3.783 V
3. V_ab = 4.5 mV
4. V_ab = 37.5 mV
5. ε = 1000 µε
6. σ = 66 MPa

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