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 = 50 ΩR₂ = 150 ΩR₃ = 50 ΩR₄ = 120 Ω

I_s = mA

2.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 = 60 ΩR₂ = 60 ΩR₃ = 10 ΩR₄ = 400 Ω

I_s = mA

3.Medium

A 1000 Ω strain gauge is one arm (R₂) of a bridge with four equal 1000 Ω arms and an excitation of 2 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 2 VR = 1000 Ω

P_g = mW

4.Medium

A bridge has four 100 Ω arms and V_s = 5 V. The sensor R₂ increases by ΔR = 10 Ω. Find the exact output V_ab in mV.

V_s = 5 VR = 100 ΩΔR = 10 Ω

V_ab = mV

5.Hard

A strain gauge (GF = 2) on a member with E = 200 GPa forms a quarter bridge excited with 3 V. The output reads 1.5 mV. Find the axial stress σ in MPa.

V_s = 3 VGF = 2V_o = 1.5 mVE = 200 GPa

σ = MPa

6.Hard

A 1000 Ω strain gauge with gauge factor 2.12 is bonded to a steel bar. Under load its resistance rises by 0.53 Ω. Find the strain ε in microstrain (µε).

R = 1000 ΩGF = 2.12ΔR = 0.53 Ω

ε = µε

Answer key

1. I_s = 65.29 mA
2. I_s = 32.32 mA
3. P_g = 1 mW
4. V_ab = 119 mV
5. σ = 200 MPa
6. ε = 250 µε

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