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.

New worksheet Practise online with hints

For teachers: free to print, copy and use in class. Every new worksheet has new values and its own answer key. A link to ExamProblems on your course page is appreciated.

Name: ____________________ Date: ____________

1.Easy

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 20 Ω, R₂ = 50 Ω and R₃ = 800 Ω. Find the unknown resistor R₄.

R₁ = 20 ΩR₂ = 50 ΩR₃ = 800 Ω

R₄ = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 600 Ω, R₂ = 40 Ω and R₄ = 80 Ω. Find the setting R₃.

R₁ = 600 ΩR₂ = 40 ΩR₄ = 80 Ω

R₃ = Ω

3.Medium

A bridge has four 120 Ω arms and V_s = 2 V. The sensor R₂ increases by ΔR = 0.24 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 2 VR = 120 ΩΔR = 0.24 Ω

V_ab = mV

4.Medium

Find the Thévenin resistance R_th of the bridge shown, seen from the output terminals a and b.

V_s = 15 VR₁ = 250 ΩR₂ = 50 ΩR₃ = 150 ΩR₄ = 120 Ω

R_th = Ω

5.Hard

A bridge with 350 Ω arms is excited with 5 V and has one active gauge (quarter bridge). The gauge factor is 2.05 and the strain is 1500 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.05ε = 1500 µε

V_o = mV

6.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 1.59 mV. Find the axial stress σ in MPa.

V_s = 3 VGF = 2.12V_o = 1.59 mVE = 70 GPa

σ = MPa

Answer key

1. R₄ = 2000 Ω
2. R₃ = 1200 Ω
3. V_ab = 1 mV
4. R_th = 108.3 Ω
5. V_o = 3.844 mV
6. σ = 70 MPa

Full step-by-step solutions: practise this topic on examproblems.com.