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 the bridge shown, V_s = 15 V, R₁ = 1000 Ω and R₂ = 1000 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 15 VR₁ = 1000 ΩR₂ = 1000 ΩR₃ = 150 ΩR₄ = 150 Ω

V_a = V

2.Easy

In a slide-wire (metre) bridge a known 100 Ω resistor sits in the left gap and an unknown resistor Rₓ in the right gap. The galvanometer reads zero when the jockey is 65 cm from the left end A of the 100 cm wire. Find R_x.

R = 100 Ωl = 65 cmL = 100 cm

R_x = Ω

3.Medium

A bridge has four 100 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 8 Ω. Find the exact output V_ab in mV.

V_s = 9 VR = 100 ΩΔR = 8 Ω

V_ab = mV

4.Medium

A 470 Ω strain gauge is one arm (R₂) of a bridge with four equal 470 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 = 470 Ω

P_g = mW

5.Hard

A strain gauge (GF = 2.12) on a member with E = 200 GPa forms a quarter bridge excited with 2.5 V. The output reads 0.265 mV. Find the axial stress σ in MPa.

V_s = 2.5 VGF = 2.12V_o = 0.265 mVE = 200 GPa

σ = MPa

6.Hard

A 350 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 0.35 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2ΔR = 0.35 Ω

ε = µε

Answer key

1. V_a = 7.5 V
2. R_x = 53.85 Ω
3. V_ab = 173.1 mV
4. P_g = 19.15 mW
5. σ = 40 MPa
6. ε = 500 µε

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