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 = 9 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 9 VR₁ = 60 ΩR₂ = 100 ΩR₃ = 600 ΩR₄ = 10 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 50 Ω, R₂ = 600 Ω and R₄ = 600 Ω. Find the setting R₃.

R₁ = 50 ΩR₂ = 600 ΩR₄ = 600 Ω

R₃ = Ω

3.Medium

A bridge with four 120 Ω arms is supplied with 12 V. When the sensor R₂ changes, the output reads V_ab = 59.41 mV. Find the exact change ΔR of R₂.

V_s = 12 VR = 120 ΩV_ab = 59.41 mV

ΔR = Ω

4.Medium

A 470 Ω strain gauge is one arm (R₂) of a bridge with four equal 470 Ω arms and an excitation of 5 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 5 VR = 470 Ω

P_g = mW

5.Hard

A quarter bridge (one active gauge, GF = 2.12) is excited with 5 V. The largest strain to be measured is 400 µε, and it must give 3.3 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 5 VGF = 2.12ε_max = 400 µεV_FS = 3.3 V

G =

6.Hard

A quarter bridge with one active gauge (GF = 2) is excited with 2.5 V. Under load the output reads 0.5 mV. Find the strain ε in µε.

V_s = 2.5 VGF = 2V_o = 0.5 mV

ε = µε

Answer key

1. I_s = 71 mA
2. R₃ = 50 Ω
3. ΔR = 2.4 Ω
4. P_g = 13.3 mW
5. G = 3113
6. ε = 400 µε

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