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 2 Ω resistor sits in the left gap and an unknown resistor Rₓ in the right gap. The galvanometer reads zero when the jockey is 75 cm from the left end A of the 100 cm wire. Find R_x.

R = 2 Ωl = 75 cmL = 100 cm

R_x = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 40 Ω, R₂ = 800 Ω and R₃ = 250 Ω. Find the unknown resistor R₄.

R₁ = 40 ΩR₂ = 800 ΩR₃ = 250 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 = 6 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 6 VR₁ = 10 ΩR₂ = 100 ΩR₃ = 40 ΩR₄ = 100 ΩR_g = 500 Ω

I_g = µA

4.Medium

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

V_s = 9 VR₁ = 60 ΩR₂ = 250 ΩR₃ = 100 ΩR₄ = 800 Ω

R_th = Ω

5.Hard

A quarter bridge with one active gauge (GF = 2.1) is excited with 10 V. Under load the output reads 1.05 mV. Find the strain ε in µε.

V_s = 10 VGF = 2.1V_o = 1.05 mV

ε = µε

6.Hard

A bridge with 120 Ω arms is excited with 2.5 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.05 and the strain is 1200 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.05ε = 1200 µε

V_o = mV

Answer key

1. R_x = 0.6667 Ω
2. R₄ = 5000 Ω
3. I_g = 2174 µA
4. R_th = 137.3 Ω
5. ε = 200 µε
6. V_o = 6.15 mV

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