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 Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 150 Ω, R₂ = 100 Ω and R₄ = 500 Ω. Find the setting R₃.

R₁ = 150 ΩR₂ = 100 ΩR₄ = 500 Ω

R₃ = Ω

2.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 6 V.

V_s = 6 VR₁ = 800 ΩR₂ = 500 ΩR₃ = 200 ΩR₄ = 100 Ω

V_ab = V

3.Medium

A bridge has four 350 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 3.5 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 9 VR = 350 ΩΔR = 3.5 Ω

V_ab = mV

4.Medium

A 250 Ω strain gauge is one arm (R₂) of a bridge with four equal 250 Ω arms and an excitation of 5 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 5 VR = 250 Ω

P_g = mW

5.Hard

A quarter bridge with one active gauge (GF = 2.12) is excited with 3 V. Under load the output reads 1.59 mV. Find the strain ε in µε.

V_s = 3 VGF = 2.12V_o = 1.59 mV

ε = µε

6.Hard

A strain gauge (GF = 2) on a member with E = 70 GPa forms a quarter bridge excited with 2.5 V. The output reads 1.875 mV. Find the axial stress σ in MPa.

V_s = 2.5 VGF = 2V_o = 1.875 mVE = 70 GPa

σ = MPa

Answer key

1. R₃ = 750 Ω
2. V_ab = 0.3077 V
3. V_ab = 22.5 mV
4. P_g = 25 mW
5. ε = 1000 µε
6. σ = 105 MPa

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