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 = 15 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 15 VR₁ = 40 ΩR₂ = 300 ΩR₃ = 150 ΩR₄ = 120 Ω

I_s = mA

2.Easy

In the bridge shown, V_s = 15 V, R₁ = 600 Ω and R₂ = 50 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 15 VR₁ = 600 ΩR₂ = 50 ΩR₃ = 60 ΩR₄ = 250 Ω

V_a = V

3.Medium

A bridge with four 350 Ω arms is supplied with 9 V. When the sensor R₂ changes, the output reads V_ab = 22.39 mV. Find the exact change ΔR of R₂.

V_s = 9 VR = 350 ΩV_ab = 22.39 mV

ΔR = Ω

4.Medium

A bridge has four 350 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 28 Ω. Find the exact output V_ab in mV.

V_s = 9 VR = 350 ΩΔR = 28 Ω

V_ab = mV

5.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 2.5 V. The largest strain to be measured is 250 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 2.5 VGF = 2ε_max = 250 µεV_FS = 5 V

G =

6.Hard

A 350 Ω strain gauge with gauge factor 2.05 is bonded to a steel bar. Under load its resistance rises by 0.5381 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2.05ΔR = 0.5381 Ω

ε = µε

Answer key

1. I_s = 99.67 mA
2. V_a = 1.154 V
3. ΔR = 3.5 Ω
4. V_ab = 173.1 mV
5. G = 16000
6. ε = 750 µε

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