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 55 cm from the left end A of the 100 cm wire. Find R_x.

R = 20 Ωl = 55 cmL = 100 cm

R_x = Ω

2.Easy

In the bridge shown, V_s = 5 V, R₁ = 50 Ω and R₂ = 40 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 5 VR₁ = 50 ΩR₂ = 40 ΩR₃ = 50 ΩR₄ = 500 Ω

V_a = V

3.Medium

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

V_s = 10 VR₁ = 100 ΩR₂ = 10 ΩR₃ = 500 ΩR₄ = 800 Ω

R_th = Ω

4.Medium

A 330 Ω strain gauge is one arm (R₂) of a bridge with four equal 330 Ω arms and an excitation of 6 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 6 VR = 330 Ω

P_g = mW

5.Hard

A load cell (a full bridge of strain gauges) has a rated output of 3 mV/V at its rated load of 100 kg. It is excited with 12 V. Find its output V_o under a load of 60 kg.

3 mV/VF_rated = 100 kgV_s = 12 VF = 60 kg

V_o = mV

6.Hard

A bridge with 120 Ω arms is excited with 5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2 and the strain is 500 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2ε = 500 µε

V_o = mV

Answer key

1. R_x = 16.36 Ω
2. V_a = 2.222 V
3. R_th = 316.8 Ω
4. P_g = 27.27 mW
5. V_o = 21.6 mV
6. V_o = 2.5 mV

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