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 = 3 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 3 VR₁ = 100 ΩR₂ = 10 ΩR₃ = 80 ΩR₄ = 200 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 200 Ω, R₂ = 800 Ω and R₄ = 60 Ω. Find the setting R₃.

R₁ = 200 ΩR₂ = 800 ΩR₄ = 60 Ω

R₃ = Ω

3.Medium

Find the Thévenin resistance R_th of the bridge shown, seen from the output terminals a and b.

V_s = 3 VR₁ = 400 ΩR₂ = 50 ΩR₃ = 200 ΩR₄ = 40 Ω

R_th = Ω

4.Medium

A bridge has four 300 Ω arms and V_s = 5 V. The sensor R₂ increases by ΔR = 75 Ω. Find the exact output V_ab in mV.

V_s = 5 VR = 300 ΩΔR = 75 Ω

V_ab = mV

5.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 3 V. The largest strain to be measured is 500 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 3 VGF = 2ε_max = 500 µεV_FS = 5 V

G =

6.Hard

A strain gauge (GF = 2.1) on a member with E = 110 GPa forms a quarter bridge excited with 2.5 V. The output reads 0.525 mV. Find the axial stress σ in MPa.

V_s = 2.5 VGF = 2.1V_o = 0.525 mVE = 110 GPa

σ = MPa

Answer key

1. I_s = 37.99 mA
2. R₃ = 15 Ω
3. R_th = 77.78 Ω
4. V_ab = 277.8 mV
5. G = 6667
6. σ = 44 MPa

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