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

The bridge shown is supplied with V_s = 5 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 5 VR₁ = 10 ΩR₂ = 120 ΩR₃ = 200 ΩR₄ = 300 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 500 Ω, R₂ = 10 Ω and R₄ = 80 Ω. Find the setting R₃.

R₁ = 500 ΩR₂ = 10 ΩR₄ = 80 Ω

R₃ = Ω

3.Medium

A bridge with four 120 Ω arms is supplied with 15 V. When the sensor R₂ changes, the output reads V_ab = 357.1 mV. Find the exact change ΔR of R₂.

V_s = 15 VR = 120 ΩV_ab = 357.1 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 = 250 ΩR₂ = 400 ΩR₃ = 10 ΩR₄ = 800 Ω

R_th = Ω

5.Hard

A quarter bridge with one active gauge (GF = 2.05) is excited with 3 V. Under load the output reads 1.23 mV. Find the strain ε in µε.

V_s = 3 VGF = 2.05V_o = 1.23 mV

ε = µε

6.Hard

A quarter bridge (one active gauge, GF = 2.12) is excited with 3 V. The largest strain to be measured is 800 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 3 VGF = 2.12ε_max = 800 µεV_FS = 5 V

G =

Answer key

1. I_s = 48.46 mA
2. R₃ = 4000 Ω
3. ΔR = 12 Ω
4. R_th = 163.7 Ω
5. ε = 800 µε
6. G = 3931

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