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 = 150 ΩR₂ = 10 ΩR₃ = 100 ΩR₄ = 20 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 150 Ω, R₂ = 40 Ω and R₄ = 200 Ω. Find the setting R₃.

R₁ = 150 ΩR₂ = 40 ΩR₄ = 200 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 = 6 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 6 VR₁ = 250 ΩR₂ = 40 ΩR₃ = 40 ΩR₄ = 10 ΩR_g = 20 Ω

I_g = µA

4.Medium

A bridge has four 200 Ω arms and V_s = 5 V. The sensor R₂ increases by ΔR = 16 Ω. Find the exact output V_ab in mV.

V_s = 5 VR = 200 ΩΔR = 16 Ω

V_ab = mV

5.Hard

A 350 Ω strain gauge with gauge factor 2.1 is bonded to a steel bar. Under load its resistance rises by 1.103 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2.1ΔR = 1.103 Ω

ε = µε

6.Hard

A load cell (a full bridge of strain gauges) has a rated output of 1.5 mV/V at its rated load of 200 kg. It is excited with 5 V. Find its output V_o under a load of 50 kg.

1.5 mV/VF_rated = 200 kgV_s = 5 VF = 50 kg

V_o = mV

Answer key

1. I_s = 87.5 mA
2. R₃ = 750 Ω
3. I_g = −5960 µA
4. V_ab = 96.15 mV
5. ε = 1500 µε
6. V_o = 1.875 mV

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