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 = 15 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 15 VR₁ = 300 ΩR₂ = 40 ΩR₃ = 100 ΩR₄ = 10 Ω

I_s = mA

2.Easy

The bridge shown is supplied with V_s = 5 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 5 VR₁ = 250 ΩR₂ = 200 ΩR₃ = 1000 ΩR₄ = 250 Ω

I_s = mA

3.Medium

A bridge with four 100 Ω arms is supplied with 5 V. When the sensor R₂ changes, the output reads V_ab = 24.75 mV. Find the exact change ΔR of R₂.

V_s = 5 VR = 100 ΩV_ab = 24.75 mV

ΔR = Ω

4.Medium

A bridge has four 400 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 0.4 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 9 VR = 400 ΩΔR = 0.4 Ω

V_ab = mV

5.Hard

A bridge with 120 Ω arms is excited with 3 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.1 and the strain is 200 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.1ε = 200 µε

V_o = mV

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 and the strain is 250 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2ε = 250 µε

V_o = mV

Answer key

1. I_s = 180.5 mA
2. I_s = 15.11 mA
3. ΔR = 2 Ω
4. V_ab = 2.25 mV
5. V_o = 1.26 mV
6. V_o = 1.25 mV

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