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 5 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 = 5 Ωl = 75 cmL = 100 cm

R_x = Ω

2.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 2 V.

V_s = 2 VR₁ = 500 ΩR₂ = 100 ΩR₃ = 500 ΩR₄ = 80 Ω

V_ab = V

3.Medium

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

V_s = 9 VR₁ = 20 ΩR₂ = 500 ΩR₃ = 40 ΩR₄ = 250 Ω

R_th = Ω

4.Medium

A 300 Ω strain gauge is one arm (R₂) of a bridge with four equal 300 Ω arms and an excitation of 3 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 3 VR = 300 Ω

P_g = mW

5.Hard

A 1000 Ω strain gauge with gauge factor 2.12 is bonded to a steel bar. Under load its resistance rises by 2.12 Ω. Find the strain ε in microstrain (µε).

R = 1000 ΩGF = 2.12ΔR = 2.12 Ω

ε = µε

6.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 250 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2ε = 250 µε

V_o = mV

Answer key

1. R_x = 1.667 Ω
2. V_ab = 0.05747 V
3. R_th = 53.71 Ω
4. P_g = 7.5 mW
5. ε = 1000 µε
6. V_o = 5 mV

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