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

In the bridge shown, V_s = 15 V, R₁ = 250 Ω and R₂ = 250 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 15 VR₁ = 250 ΩR₂ = 250 ΩR₃ = 100 ΩR₄ = 80 Ω

V_a = V

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 250 Ω, R₂ = 40 Ω and R₄ = 100 Ω. Find the setting R₃.

R₁ = 250 ΩR₂ = 40 ΩR₄ = 100 Ω

R₃ = Ω

3.Medium

A bridge has four 350 Ω arms and V_s = 10 V. The sensor R₂ increases by ΔR = 0.875 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 10 VR = 350 ΩΔR = 0.875 Ω

V_ab = mV

4.Medium

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

V_s = 9 VR₁ = 600 ΩR₂ = 20 ΩR₃ = 800 ΩR₄ = 300 Ω

R_th = Ω

5.Hard

A quarter bridge with one active gauge (GF = 2.05) is excited with 10 V. Under load the output reads 5.125 mV. Find the strain ε in µε.

V_s = 10 VGF = 2.05V_o = 5.125 mV

ε = µε

6.Hard

A load cell (a full bridge of strain gauges) has a rated output of 2 mV/V at its rated load of 100 kg. It is excited with 10 V. Find its output V_o under a load of 50 kg.

2 mV/VF_rated = 100 kgV_s = 10 VF = 50 kg

V_o = mV

Answer key

1. V_a = 7.5 V
2. R₃ = 625 Ω
3. V_ab = 6.25 mV
4. R_th = 237.5 Ω
5. ε = 1000 µε
6. V_o = 10 mV

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