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 = 9 V.

V_s = 9 VR₁ = 800 ΩR₂ = 250 ΩR₃ = 600 ΩR₄ = 50 Ω

V_ab = V

2.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 15 V.

V_s = 15 VR₁ = 120 ΩR₂ = 500 ΩR₃ = 500 ΩR₄ = 50 Ω

V_ab = V

3.Medium

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

V_s = 12 VR₁ = 40 ΩR₂ = 60 ΩR₃ = 1000 ΩR₄ = 800 Ω

R_th = Ω

4.Medium

A bridge has four 100 Ω arms and V_s = 12 V. The sensor R₂ increases by ΔR = 1 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 12 VR = 100 ΩΔR = 1 Ω

V_ab = mV

5.Hard

A bridge with 120 Ω arms is excited with 3 V and has one active gauge (quarter bridge). The gauge factor is 2.12 and the strain is 500 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.12ε = 500 µε

V_o = mV

6.Hard

A 1000 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 1 Ω. Find the strain ε in microstrain (µε).

R = 1000 ΩGF = 2ΔR = 1 Ω

ε = µε

Answer key

1. V_ab = 1.451 V
2. V_ab = 10.73 V
3. R_th = 468.4 Ω
4. V_ab = 30 mV
5. V_o = 0.795 mV
6. ε = 500 µε

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