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 = 6 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 6 VR₁ = 400 ΩR₂ = 100 ΩR₃ = 250 ΩR₄ = 10 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 20 Ω, R₂ = 80 Ω and R₄ = 60 Ω. Find the setting R₃.

R₁ = 20 ΩR₂ = 80 ΩR₄ = 60 Ω

R₃ = Ω

3.Medium

A galvanometer with a resistance of 20 Ω is connected between a and b of the bridge shown (V_s = 3 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 3 VR₁ = 1000 ΩR₂ = 800 ΩR₃ = 600 ΩR₄ = 50 ΩR_g = 20 Ω

I_g = µA

4.Medium

A bridge has four 1000 Ω arms and V_s = 10 V. The sensor R₂ increases by ΔR = 2.5 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 10 VR = 1000 ΩΔR = 2.5 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 2.12 and the strain is 750 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.12ε = 750 µε

V_o = mV

6.Hard

A bridge with 350 Ω arms is excited with 2.5 V and has one active gauge (quarter bridge). The gauge factor is 2.12 and the strain is 1200 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.12ε = 1200 µε

V_o = mV

Answer key

1. I_s = 35.08 mA
2. R₃ = 15 Ω
3. I_g = 2159 µA
4. V_ab = 6.25 mV
5. V_o = 4.77 mV
6. V_o = 1.59 mV

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