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 = 6 V.

V_s = 6 VR₁ = 150 ΩR₂ = 50 ΩR₃ = 40 ΩR₄ = 120 Ω

V_ab = V

2.Easy

In the bridge shown, V_s = 5 V, R₁ = 500 Ω and R₂ = 100 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 5 VR₁ = 500 ΩR₂ = 100 ΩR₃ = 800 ΩR₄ = 400 Ω

V_a = V

3.Medium

A bridge with four 250 Ω arms is supplied with 15 V. When the sensor R₂ changes, the output reads V_ab = 147.1 mV. Find the exact change ΔR of R₂.

V_s = 15 VR = 250 ΩV_ab = 147.1 mV

ΔR = Ω

4.Medium

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

V_s = 15 VR₁ = 1000 ΩR₂ = 600 ΩR₃ = 200 ΩR₄ = 100 Ω

R_th = Ω

5.Hard

A strain gauge (GF = 2.1) on a member with E = 200 GPa forms a quarter bridge excited with 2.5 V. The output reads 0.263 mV. Find the axial stress σ in MPa.

V_s = 2.5 VGF = 2.1V_o = 0.263 mVE = 200 GPa

σ = MPa

6.Hard

A bridge with 120 Ω arms is excited with 2.5 V and has one active gauge (quarter bridge). The gauge factor is 2 and the strain is 750 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2ε = 750 µε

V_o = mV

Answer key

1. V_ab = −3 V
2. V_a = 0.8333 V
3. ΔR = 10 Ω
4. R_th = 441.7 Ω
5. σ = 40.08 MPa
6. V_o = 0.9375 mV

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