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 bridge shown is supplied with V_s = 12 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 12 VR₁ = 200 ΩR₂ = 1000 ΩR₃ = 400 ΩR₄ = 40 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 250 Ω, R₂ = 80 Ω and R₃ = 20 Ω. Find the unknown resistor R₄.

R₁ = 250 ΩR₂ = 80 ΩR₃ = 20 Ω

R₄ = Ω

3.Medium

A bridge with four 300 Ω arms is supplied with 3 V. When the sensor R₂ changes, the output reads V_ab = 7.46 mV. Find the exact change ΔR of R₂.

V_s = 3 VR = 300 ΩV_ab = 7.46 mV

ΔR = Ω

4.Medium

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

V_s = 10 VR₁ = 50 ΩR₂ = 300 ΩR₃ = 100 ΩR₄ = 500 Ω

R_th = Ω

5.Hard

A bridge with 120 Ω arms is excited with 10 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2 and the strain is 400 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2ε = 400 µε

V_o = mV

6.Hard

A bridge with 350 Ω arms is excited with 3 V and has one active gauge (quarter bridge). The gauge factor is 2.12 and the strain is 1200 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.12ε = 1200 µε

V_o = mV

Answer key

1. I_s = 37.27 mA
2. R₄ = 6.4 Ω
3. ΔR = 2.999 Ω
4. R_th = 126.2 Ω
5. V_o = 8 mV
6. V_o = 1.908 mV

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