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 = 20 Ω, R₂ = 600 Ω and R₄ = 600 Ω. Find the setting R₃.

R₁ = 20 ΩR₂ = 600 ΩR₄ = 600 Ω

R₃ = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 500 Ω, R₂ = 200 Ω and R₄ = 200 Ω. Find the setting R₃.

R₁ = 500 ΩR₂ = 200 ΩR₄ = 200 Ω

R₃ = Ω

3.Medium

A bridge has four 300 Ω arms and V_s = 12 V. The sensor R₂ increases by ΔR = 0.6 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 12 VR = 300 ΩΔR = 0.6 Ω

V_ab = mV

4.Medium

A galvanometer with a resistance of 50 Ω is connected between a and b of the bridge shown (V_s = 9 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 9 VR₁ = 250 ΩR₂ = 500 ΩR₃ = 200 ΩR₄ = 20 ΩR_g = 50 Ω

I_g = µA

5.Hard

A quarter bridge with one active gauge (GF = 2.1) is excited with 3 V. Under load the output reads 0.394 mV. Find the strain ε in µε.

V_s = 3 VGF = 2.1V_o = 0.394 mV

ε = µε

6.Hard

A strain gauge (GF = 2.1) on a member with E = 70 GPa forms a quarter bridge excited with 3 V. The output reads 1.89 mV. Find the axial stress σ in MPa.

V_s = 3 VGF = 2.1V_o = 1.89 mVE = 70 GPa

σ = MPa

Answer key

1. R₃ = 20 Ω
2. R₃ = 500 Ω
3. V_ab = 6 mV
4. I_g = 22065 µA
5. ε = 250.2 µε
6. σ = 84 MPa

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