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 = 50 ΩR₂ = 400 ΩR₃ = 800 ΩR₄ = 1000 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 40 Ω, R₂ = 10 Ω and R₄ = 200 Ω. Find the setting R₃.

R₁ = 40 ΩR₂ = 10 ΩR₄ = 200 Ω

R₃ = Ω

3.Medium

A bridge with four 120 Ω arms is supplied with 2 V. When the sensor R₂ changes, the output reads V_ab = 9.9 mV. Find the exact change ΔR of R₂.

V_s = 2 VR = 120 ΩV_ab = 9.9 mV

ΔR = Ω

4.Medium

A bridge has four 150 Ω arms and V_s = 3 V. The sensor R₂ increases by ΔR = 7.5 Ω. Find the exact output V_ab in mV.

V_s = 3 VR = 150 ΩΔR = 7.5 Ω

V_ab = mV

5.Hard

A load cell (a full bridge of strain gauges) has a rated output of 3 mV/V at its rated load of 500 kg. It is excited with 12 V. Find its output V_o under a load of 400 kg.

3 mV/VF_rated = 500 kgV_s = 12 VF = 400 kg

V_o = mV

6.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 and the strain is 400 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2ε = 400 µε

V_o = mV

Answer key

1. I_s = 33.33 mA
2. R₃ = 800 Ω
3. ΔR = 2.4 Ω
4. V_ab = 36.59 mV
5. V_o = 28.8 mV
6. V_o = 2 mV

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