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 = 12 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 12 VR₁ = 300 ΩR₂ = 100 ΩR₃ = 250 ΩR₄ = 80 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 80 Ω, R₂ = 500 Ω and R₄ = 150 Ω. Find the setting R₃.

R₁ = 80 ΩR₂ = 500 ΩR₄ = 150 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 = 50 ΩR₂ = 400 ΩR₃ = 200 ΩR₄ = 250 Ω

R_th = Ω

4.Medium

A bridge with four 1000 Ω arms is supplied with 6 V. When the sensor R₂ changes, the output reads V_ab = 142.9 mV. Find the exact change ΔR of R₂.

V_s = 6 VR = 1000 ΩV_ab = 142.9 mV

ΔR = Ω

5.Hard

A bridge with 350 Ω arms is excited with 5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.12 and the strain is 200 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.12ε = 200 µε

V_o = mV

6.Hard

A 350 Ω strain gauge with gauge factor 2.05 is bonded to a steel bar. Under load its resistance rises by 0.861 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2.05ΔR = 0.861 Ω

ε = µε

Answer key

1. I_s = 66.36 mA
2. R₃ = 24 Ω
3. R_th = 155.6 Ω
4. ΔR = 100 Ω
5. V_o = 1.06 mV
6. ε = 1200 µε

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