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 = 100 Ω, R₂ = 40 Ω and R₄ = 800 Ω. Find the setting R₃.

R₁ = 100 ΩR₂ = 40 ΩR₄ = 800 Ω

R₃ = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 1000 Ω, R₂ = 300 Ω and R₃ = 300 Ω. Find the unknown resistor R₄.

R₁ = 1000 ΩR₂ = 300 ΩR₃ = 300 Ω

R₄ = Ω

3.Medium

A galvanometer with a resistance of 500 Ω is connected between a and b of the bridge shown (V_s = 3 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 3 VR₁ = 500 ΩR₂ = 100 ΩR₃ = 200 ΩR₄ = 80 ΩR_g = 500 Ω

I_g = µA

4.Medium

A galvanometer with a resistance of 100 Ω is connected between a and b of the bridge shown (V_s = 9 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 9 VR₁ = 250 ΩR₂ = 20 ΩR₃ = 100 ΩR₄ = 20 ΩR_g = 100 Ω

I_g = µA

5.Hard

A strain gauge (GF = 2.12) on a member with E = 70 GPa forms a quarter bridge excited with 3 V. The output reads 0.636 mV. Find the axial stress σ in MPa.

V_s = 3 VGF = 2.12V_o = 0.636 mVE = 70 GPa

σ = MPa

6.Hard

A bridge with 350 Ω arms is excited with 5 V and has one active gauge (quarter bridge). The gauge factor is 2.12 and the strain is 600 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.12ε = 600 µε

V_o = mV

Answer key

1. R₃ = 2000 Ω
2. R₄ = 90 Ω
3. I_g = −557.6 µA
4. I_g = −6164 µA
5. σ = 28 MPa
6. V_o = 1.59 mV

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