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

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 6 V.

V_s = 6 VR₁ = 120 ΩR₂ = 60 ΩR₃ = 10 ΩR₄ = 150 Ω

V_ab = V

2.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 = 250 ΩR₂ = 250 ΩR₃ = 10 ΩR₄ = 250 Ω

I_s = mA

3.Medium

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

V_s = 3 VR₁ = 60 ΩR₂ = 500 ΩR₃ = 400 ΩR₄ = 1000 Ω

R_th = Ω

4.Medium

A bridge has four 220 Ω arms and V_s = 5 V. The sensor R₂ increases by ΔR = 0.55 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 5 VR = 220 ΩΔR = 0.55 Ω

V_ab = mV

5.Hard

A quarter bridge with one active gauge (GF = 2.1) is excited with 10 V. Under load the output reads 2.625 mV. Find the strain ε in µε.

V_s = 10 VGF = 2.1V_o = 2.625 mV

ε = µε

6.Hard

A bridge with 350 Ω arms is excited with 10 V and has one active gauge (quarter bridge). The gauge factor is 2.1 and the strain is 1000 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2.1ε = 1000 µε

V_o = mV

Answer key

1. V_ab = −3.625 V
2. I_s = 17.54 mA
3. R_th = 339.3 Ω
4. V_ab = 3.125 mV
5. ε = 500 µε
6. V_o = 5.25 mV

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