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 = 80 Ω, R₂ = 300 Ω and R₃ = 50 Ω. Find the unknown resistor R₄.

R₁ = 80 ΩR₂ = 300 ΩR₃ = 50 Ω

R₄ = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 120 Ω, R₂ = 200 Ω and R₄ = 150 Ω. Find the setting R₃.

R₁ = 120 ΩR₂ = 200 ΩR₄ = 150 Ω

R₃ = Ω

3.Medium

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

V_s = 12 VR₁ = 120 ΩR₂ = 100 ΩR₃ = 100 ΩR₄ = 10 Ω

R_th = Ω

4.Medium

A bridge has four 120 Ω arms and V_s = 6 V. The sensor R₂ increases by ΔR = 0.24 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 6 VR = 120 ΩΔR = 0.24 Ω

V_ab = mV

5.Hard

A bridge with 350 Ω arms is excited with 5 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.1 and the strain is 200 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.1ε = 200 µε

V_o = mV

6.Hard

A quarter bridge with one active gauge (GF = 2) is excited with 2.5 V. Under load the output reads 1.5 mV. Find the strain ε in µε.

V_s = 2.5 VGF = 2V_o = 1.5 mV

ε = µε

Answer key

1. R₄ = 187.5 Ω
2. R₃ = 90 Ω
3. R_th = 63.64 Ω
4. V_ab = 3 mV
5. V_o = 2.1 mV
6. ε = 1200 µε

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