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.

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1.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 5 V.

V_s = 5 VR₁ = 800 ΩR₂ = 1000 ΩR₃ = 300 ΩR₄ = 50 Ω

V_ab = V

2.Easy

In the bridge shown, V_s = 15 V, R₁ = 80 Ω and R₂ = 100 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 15 VR₁ = 80 ΩR₂ = 100 ΩR₃ = 600 ΩR₄ = 120 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 = 3 VR₁ = 20 ΩR₂ = 500 ΩR₃ = 100 ΩR₄ = 60 Ω

R_th = Ω

4.Medium

A bridge with four 200 Ω arms is supplied with 10 V. When the sensor R₂ changes, the output reads V_ab = 24.88 mV. Find the exact change ΔR of R₂.

V_s = 10 VR = 200 ΩV_ab = 24.88 mV

ΔR = Ω

5.Hard

A strain gauge (GF = 2.05) on a member with E = 110 GPa forms a quarter bridge excited with 10 V. The output reads 5.125 mV. Find the axial stress σ in MPa.

V_s = 10 VGF = 2.05V_o = 5.125 mVE = 110 GPa

σ = MPa

6.Hard

A load cell (a full bridge of strain gauges) has a rated output of 3 mV/V at its rated load of 50 kg. It is excited with 10 V. Find its output V_o under a load of 10 kg.

3 mV/VF_rated = 50 kgV_s = 10 VF = 10 kg

V_o = mV

Answer key

1. V_ab = 2.063 V
2. V_a = 8.333 V
3. R_th = 56.73 Ω
4. ΔR = 2 Ω
5. σ = 110 MPa
6. V_o = 6 mV

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