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 Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 120 Ω, R₂ = 500 Ω and R₄ = 10 Ω. Find the setting R₃.

R₁ = 120 ΩR₂ = 500 ΩR₄ = 10 Ω

R₃ = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 120 Ω, R₂ = 400 Ω and R₄ = 60 Ω. Find the setting R₃.

R₁ = 120 ΩR₂ = 400 ΩR₄ = 60 Ω

R₃ = Ω

3.Medium

A galvanometer with a resistance of 200 Ω is connected between a and b of the bridge shown (V_s = 12 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 12 VR₁ = 250 ΩR₂ = 800 ΩR₃ = 500 ΩR₄ = 800 ΩR_g = 200 Ω

I_g = µA

4.Medium

A 220 Ω strain gauge is one arm (R₂) of a bridge with four equal 220 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 = 220 Ω

P_g = mW

5.Hard

A quarter bridge with one active gauge (GF = 2) is excited with 5 V. Under load the output reads 3.75 mV. Find the strain ε in µε.

V_s = 5 VGF = 2V_o = 3.75 mV

ε = µε

6.Hard

A strain gauge (GF = 2) on a member with E = 210 GPa forms a quarter bridge excited with 2.5 V. The output reads 1.5 mV. Find the axial stress σ in MPa.

V_s = 2.5 VGF = 2V_o = 1.5 mVE = 210 GPa

σ = MPa

Answer key

1. R₃ = 2.4 Ω
2. R₃ = 18 Ω
3. I_g = 2518 µA
4. P_g = 113.6 mW
5. ε = 1500 µε
6. σ = 252 MPa

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