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 = 6 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 6 VR₁ = 10 ΩR₂ = 80 ΩR₃ = 400 ΩR₄ = 1000 Ω

I_s = mA

2.Easy

In the bridge shown, V_s = 6 V, R₁ = 400 Ω and R₂ = 100 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 6 VR₁ = 400 ΩR₂ = 100 ΩR₃ = 60 ΩR₄ = 80 Ω

V_a = V

3.Medium

A bridge has four 220 Ω arms and V_s = 12 V. The sensor R₂ increases by ΔR = 11 Ω. Find the exact output V_ab in mV.

V_s = 12 VR = 220 ΩΔR = 11 Ω

V_ab = mV

4.Medium

A bridge with four 470 Ω arms is supplied with 12 V. When the sensor R₂ changes, the output reads V_ab = 146.3 mV. Find the exact change ΔR of R₂.

V_s = 12 VR = 470 ΩV_ab = 146.3 mV

ΔR = Ω

5.Hard

A quarter bridge with one active gauge (GF = 2) is excited with 2.5 V. Under load the output reads 1.875 mV. Find the strain ε in µε.

V_s = 2.5 VGF = 2V_o = 1.875 mV

ε = µε

6.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 5 V. The largest strain to be measured is 500 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 5 VGF = 2ε_max = 500 µεV_FS = 5 V

G =

Answer key

1. I_s = 70.95 mA
2. V_a = 1.2 V
3. V_ab = 146.3 mV
4. ΔR = 23.5 Ω
5. ε = 1500 µε
6. G = 4000

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