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

In the bridge shown, V_s = 3 V, R₁ = 80 Ω and R₂ = 40 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 3 VR₁ = 80 ΩR₂ = 40 ΩR₃ = 800 ΩR₄ = 20 Ω

V_a = V

2.Easy

The bridge shown is supplied with V_s = 10 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 10 VR₁ = 300 ΩR₂ = 100 ΩR₃ = 20 ΩR₄ = 500 Ω

I_s = mA

3.Medium

A bridge with four 120 Ω arms is supplied with 12 V. When the sensor R₂ changes, the output reads V_ab = 285.7 mV. Find the exact change ΔR of R₂.

V_s = 12 VR = 120 ΩV_ab = 285.7 mV

ΔR = Ω

4.Medium

A bridge with four 200 Ω arms is supplied with 6 V. When the sensor R₂ changes, the output reads V_ab = 73.17 mV. Find the exact change ΔR of R₂.

V_s = 6 VR = 200 ΩV_ab = 73.17 mV

ΔR = Ω

5.Hard

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

R = 1000 ΩGF = 2ΔR = 2 Ω

ε = µε

6.Hard

A load cell (a full bridge of strain gauges) has a rated output of 2.5 mV/V at its rated load of 100 kg. It is excited with 5 V. Find its output V_o under a load of 60 kg.

2.5 mV/VF_rated = 100 kgV_s = 5 VF = 60 kg

V_o = mV

Answer key

1. V_a = 1 V
2. I_s = 44.23 mA
3. ΔR = 12 Ω
4. ΔR = 10 Ω
5. ε = 1000 µε
6. V_o = 7.5 mV

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