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 = 10 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 10 VR₁ = 1000 ΩR₂ = 120 ΩR₃ = 20 ΩR₄ = 400 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 40 Ω, R₂ = 100 Ω and R₄ = 800 Ω. Find the setting R₃.

R₁ = 40 ΩR₂ = 100 ΩR₄ = 800 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 = 10 VR₁ = 20 ΩR₂ = 40 ΩR₃ = 20 ΩR₄ = 500 Ω

R_th = Ω

4.Medium

A bridge has four 100 Ω arms and V_s = 3 V. The sensor R₂ increases by ΔR = 8 Ω. Find the exact output V_ab in mV.

V_s = 3 VR = 100 ΩΔR = 8 Ω

V_ab = mV

5.Hard

A strain gauge (GF = 2.05) on a member with E = 110 GPa forms a quarter bridge excited with 3 V. The output reads 2.306 mV. Find the axial stress σ in MPa.

V_s = 3 VGF = 2.05V_o = 2.306 mVE = 110 GPa

σ = MPa

6.Hard

A bridge with 1000 Ω arms is excited with 10 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.05 and the strain is 400 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2.05ε = 400 µε

V_o = mV

Answer key

1. I_s = 32.74 mA
2. R₃ = 320 Ω
3. R_th = 32.56 Ω
4. V_ab = 57.69 mV
5. σ = 165 MPa
6. V_o = 8.2 mV

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