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

The bridge shown is supplied with V_s = 6 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 6 VR₁ = 250 ΩR₂ = 20 ΩR₃ = 20 ΩR₄ = 120 Ω

I_s = mA

2.Easy

The bridge shown is supplied with V_s = 2 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 2 VR₁ = 200 ΩR₂ = 60 ΩR₃ = 40 ΩR₄ = 60 Ω

I_s = mA

3.Medium

A bridge has four 150 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 0.75 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 9 VR = 150 ΩΔR = 0.75 Ω

V_ab = mV

4.Medium

A bridge has four 300 Ω arms and V_s = 5 V. The sensor R₂ increases by ΔR = 3 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 5 VR = 300 ΩΔR = 3 Ω

V_ab = mV

5.Hard

A strain gauge (GF = 2.1) on a member with E = 210 GPa forms a quarter bridge excited with 10 V. The output reads 2.625 mV. Find the axial stress σ in MPa.

V_s = 10 VGF = 2.1V_o = 2.625 mVE = 210 GPa

σ = MPa

6.Hard

A quarter bridge with one active gauge (GF = 2) is excited with 10 V. Under load the output reads 7.5 mV. Find the strain ε in µε.

V_s = 10 VGF = 2V_o = 7.5 mV

ε = µε

Answer key

1. I_s = 65.08 mA
2. I_s = 27.69 mA
3. V_ab = 11.25 mV
4. V_ab = 12.5 mV
5. σ = 105 MPa
6. ε = 1500 µε

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