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 = 100 ΩR₂ = 200 ΩR₃ = 100 ΩR₄ = 1000 Ω

I_s = mA

2.Easy

The bridge shown is supplied with V_s = 15 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 15 VR₁ = 800 ΩR₂ = 600 ΩR₃ = 10 ΩR₄ = 500 Ω

I_s = mA

3.Medium

A 350 Ω strain gauge is one arm (R₂) of a bridge with four equal 350 Ω arms and an excitation of 10 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 10 VR = 350 Ω

P_g = mW

4.Medium

A bridge with four 300 Ω arms is supplied with 15 V. When the sensor R₂ changes, the output reads V_ab = 147.1 mV. Find the exact change ΔR of R₂.

V_s = 15 VR = 300 ΩV_ab = 147.1 mV

ΔR = Ω

5.Hard

A 120 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 0.144 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2ΔR = 0.144 Ω

ε = µε

6.Hard

A 350 Ω strain gauge with gauge factor 2.05 is bonded to a steel bar. Under load its resistance rises by 0.574 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2.05ΔR = 0.574 Ω

ε = µε

Answer key

1. I_s = 12.73 mA
2. I_s = 40.13 mA
3. P_g = 71.43 mW
4. ΔR = 12 Ω
5. ε = 600 µε
6. ε = 800 µε

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