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 = 9 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 9 VR₁ = 10 ΩR₂ = 600 ΩR₃ = 800 ΩR₄ = 400 Ω

I_s = mA

2.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 = 500 ΩR₃ = 40 ΩR₄ = 200 Ω

V_ab = V

3.Medium

A 150 Ω strain gauge is one arm (R₂) of a bridge with four equal 150 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 = 150 Ω

P_g = mW

4.Medium

A bridge has four 1000 Ω arms and V_s = 12 V. The sensor R₂ increases by ΔR = 50 Ω. Find the exact output V_ab in mV.

V_s = 12 VR = 1000 ΩΔR = 50 Ω

V_ab = mV

5.Hard

A quarter bridge with one active gauge (GF = 2.12) is excited with 5 V. Under load the output reads 3.975 mV. Find the strain ε in µε.

V_s = 5 VGF = 2.12V_o = 3.975 mV

ε = µε

6.Hard

A bridge with 1000 Ω arms is excited with 10 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2 and the strain is 750 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2ε = 750 µε

V_o = mV

Answer key

1. I_s = 22.25 mA
2. V_ab = −6.731 V
3. P_g = 15 mW
4. V_ab = 146.3 mV
5. ε = 1500 µε
6. V_o = 7.5 mV

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