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 = 3 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 3 VR₁ = 80 ΩR₂ = 200 ΩR₃ = 800 ΩR₄ = 120 Ω

I_s = mA

2.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 = 500 ΩR₃ = 300 ΩR₄ = 800 Ω

I_s = mA

3.Medium

A bridge has four 500 Ω arms and V_s = 6 V. The sensor R₂ increases by ΔR = 0.5 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 6 VR = 500 ΩΔR = 0.5 Ω

V_ab = mV

4.Medium

A bridge has four 250 Ω arms and V_s = 12 V. The sensor R₂ increases by ΔR = 2.5 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 12 VR = 250 ΩΔR = 2.5 Ω

V_ab = mV

5.Hard

A load cell (a full bridge of strain gauges) has a rated output of 1.5 mV/V at its rated load of 50 kg. It is excited with 12 V. Find its output V_o under a load of 40 kg.

1.5 mV/VF_rated = 50 kgV_s = 12 VF = 40 kg

V_o = mV

6.Hard

A load cell (a full bridge of strain gauges) has a rated output of 2 mV/V at its rated load of 50 kg. It is excited with 5 V. Find its output V_o under a load of 37.5 kg.

2 mV/VF_rated = 50 kgV_s = 5 VF = 37.5 kg

V_o = mV

Answer key

1. I_s = 13.98 mA
2. I_s = 12.12 mA
3. V_ab = 1.5 mV
4. V_ab = 30 mV
5. V_o = 14.4 mV
6. V_o = 7.5 mV

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