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

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 5 V.

V_s = 5 VR₁ = 60 ΩR₂ = 800 ΩR₃ = 600 ΩR₄ = 600 Ω

V_ab = V

2.Easy

The bridge shown is supplied with V_s = 10 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 10 VR₁ = 600 ΩR₂ = 600 ΩR₃ = 600 ΩR₄ = 150 Ω

I_s = mA

3.Medium

A bridge has four 200 Ω arms and V_s = 2 V. The sensor R₂ increases by ΔR = 1.6 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 2 VR = 200 ΩΔR = 1.6 Ω

V_ab = mV

4.Medium

A bridge has four 120 Ω arms and V_s = 2 V. The sensor R₂ increases by ΔR = 12 Ω. Find the exact output V_ab in mV.

V_s = 2 VR = 120 ΩΔR = 12 Ω

V_ab = mV

5.Hard

A quarter bridge (one active gauge, GF = 2.05) is excited with 5 V. The largest strain to be measured is 250 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 = 2.05ε_max = 250 µεV_FS = 3.3 V

G =

6.Hard

A bridge with 1000 Ω arms is excited with 10 V and has one active gauge (quarter bridge). The gauge factor is 2.12 and the strain is 800 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2.12ε = 800 µε

V_o = mV

Answer key

1. V_ab = 2.151 V
2. I_s = 21.67 mA
3. V_ab = 4 mV
4. V_ab = 47.62 mV
5. G = 5151
6. V_o = 4.24 mV

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