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

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 15 V.

V_s = 15 VR₁ = 800 ΩR₂ = 600 ΩR₃ = 120 ΩR₄ = 150 Ω

V_ab = V

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 = 500 ΩR₂ = 150 ΩR₃ = 80 ΩR₄ = 10 Ω

I_s = mA

3.Medium

A bridge has four 400 Ω arms and V_s = 15 V. The sensor R₂ increases by ΔR = 40 Ω. Find the exact output V_ab in mV.

V_s = 15 VR = 400 ΩΔR = 40 Ω

V_ab = mV

4.Medium

A 500 Ω strain gauge is one arm (R₂) of a bridge with four equal 500 Ω arms and an excitation of 3 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 3 VR = 500 Ω

P_g = mW

5.Hard

A load cell (a full bridge of strain gauges) has a rated output of 3 mV/V at its rated load of 200 kg. It is excited with 12 V. Find its output V_o under a load of 150 kg.

3 mV/VF_rated = 200 kgV_s = 12 VF = 150 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 2.65 mV. Find the strain ε in µε.

V_s = 5 VGF = 2.12V_o = 2.65 mV

ε = µε

Answer key

1. V_ab = −1.905 V
2. I_s = 75.9 mA
3. V_ab = 357.1 mV
4. P_g = 4.5 mW
5. V_o = 27 mV
6. ε = 1000 µε

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