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

In a slide-wire (metre) bridge a known 20 Ω resistor sits in the left gap and an unknown resistor Rₓ in the right gap. The galvanometer reads zero when the jockey is 45 cm from the left end A of the 100 cm wire. Find R_x.

R = 20 Ωl = 45 cmL = 100 cm

R_x = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 120 Ω, R₂ = 60 Ω and R₄ = 100 Ω. Find the setting R₃.

R₁ = 120 ΩR₂ = 60 ΩR₄ = 100 Ω

R₃ = Ω

3.Medium

A bridge has four 400 Ω arms and V_s = 5 V. The sensor R₂ increases by ΔR = 60 Ω. Find the exact output V_ab in mV.

V_s = 5 VR = 400 ΩΔR = 60 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 = 120 ΩR₂ = 1000 ΩR₃ = 200 ΩR₄ = 120 Ω

R_th = Ω

5.Hard

A 120 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 0.18 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2ΔR = 0.18 Ω

ε = µε

6.Hard

A load cell (a full bridge of strain gauges) has a rated output of 1 mV/V at its rated load of 500 kg. It is excited with 12 V. Find its output V_o under a load of 400 kg.

1 mV/VF_rated = 500 kgV_s = 12 VF = 400 kg

V_o = mV

Answer key

1. R_x = 24.44 Ω
2. R₃ = 200 Ω
3. V_ab = 174.4 mV
4. R_th = 182.1 Ω
5. ε = 750 µε
6. V_o = 9.6 mV

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