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 Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 150 Ω, R₂ = 10 Ω and R₄ = 200 Ω. Find the setting R₃.

R₁ = 150 ΩR₂ = 10 ΩR₄ = 200 Ω

R₃ = Ω

2.Easy

The bridge shown is supplied with V_s = 2 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 2 VR₁ = 1000 ΩR₂ = 600 ΩR₃ = 800 ΩR₄ = 20 Ω

I_s = mA

3.Medium

A bridge has four 330 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 3.3 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 9 VR = 330 ΩΔR = 3.3 Ω

V_ab = mV

4.Medium

A galvanometer with a resistance of 50 Ω is connected between a and b of the bridge shown (V_s = 5 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 5 VR₁ = 200 ΩR₂ = 600 ΩR₃ = 300 ΩR₄ = 200 ΩR_g = 50 Ω

I_g = µA

5.Hard

A load cell (a full bridge of strain gauges) has a rated output of 3 mV/V at its rated load of 100 kg. It is excited with 5 V. Find its output V_o under a load of 40 kg.

3 mV/VF_rated = 100 kgV_s = 5 VF = 40 kg

V_o = mV

6.Hard

A quarter bridge with one active gauge (GF = 2.12) is excited with 5 V. Under load the output reads 0.663 mV. Find the strain ε in µε.

V_s = 5 VGF = 2.12V_o = 0.663 mV

ε = µε

Answer key

1. R₃ = 3000 Ω
2. I_s = 3.689 mA
3. V_ab = 22.5 mV
4. I_g = 5469 µA
5. V_o = 6 mV
6. ε = 250.2 µε

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