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 = 500 Ω and R₄ = 100 Ω. Find the setting R₃.

R₁ = 150 ΩR₂ = 500 ΩR₄ = 100 Ω

R₃ = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 300 Ω, R₂ = 250 Ω and R₄ = 1000 Ω. Find the setting R₃.

R₁ = 300 ΩR₂ = 250 ΩR₄ = 1000 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 = 15 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 15 VR₁ = 100 ΩR₂ = 10 ΩR₃ = 80 ΩR₄ = 100 ΩR_g = 20 Ω

I_g = µA

4.Medium

A bridge has four 350 Ω arms and V_s = 2 V. The sensor R₂ increases by ΔR = 52.5 Ω. Find the exact output V_ab in mV.

V_s = 2 VR = 350 ΩΔR = 52.5 Ω

V_ab = mV

5.Hard

A quarter bridge (one active gauge, GF = 2.05) is excited with 5 V. The largest strain to be measured is 1500 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 5 VGF = 2.05ε_max = 1500 µεV_FS = 5 V

G =

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 20 kg.

2.5 mV/VF_rated = 100 kgV_s = 5 VF = 20 kg

V_o = mV

Answer key

1. R₃ = 30 Ω
2. R₃ = 1200 Ω
3. I_g = −94780 µA
4. V_ab = 69.77 mV
5. G = 1301
6. V_o = 2.5 mV

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