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 = 60 Ω and R₄ = 20 Ω. Find the setting R₃.

R₁ = 150 ΩR₂ = 60 ΩR₄ = 20 Ω

R₃ = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 40 Ω, R₂ = 800 Ω and R₄ = 250 Ω. Find the setting R₃.

R₁ = 40 ΩR₂ = 800 ΩR₄ = 250 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 = 6 VR₁ = 100 ΩR₂ = 600 ΩR₃ = 1000 ΩR₄ = 40 Ω

R_th = Ω

4.Medium

A bridge has four 400 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 20 Ω. Find the exact output V_ab in mV.

V_s = 9 VR = 400 ΩΔR = 20 Ω

V_ab = mV

5.Hard

A quarter bridge with one active gauge (GF = 2.12) is excited with 5 V. Under load the output reads 2.12 mV. Find the strain ε in µε.

V_s = 5 VGF = 2.12V_o = 2.12 mV

ε = µε

6.Hard

A bridge with 120 Ω arms is excited with 5 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 = 5 VGF = 2.05ε = 400 µε

V_o = mV

Answer key

1. R₃ = 50 Ω
2. R₃ = 12.5 Ω
3. R_th = 124.2 Ω
4. V_ab = 109.8 mV
5. ε = 800 µε
6. V_o = 4.1 mV

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