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 = 12 V.

V_s = 12 VR₁ = 60 ΩR₂ = 300 ΩR₃ = 20 ΩR₄ = 120 Ω

V_ab = V

2.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 15 V.

V_s = 15 VR₁ = 10 ΩR₂ = 40 ΩR₃ = 120 ΩR₄ = 150 Ω

V_ab = V

3.Medium

A bridge has four 400 Ω arms and V_s = 2 V. The sensor R₂ increases by ΔR = 80 Ω. Find the exact output V_ab in mV.

V_s = 2 VR = 400 ΩΔR = 80 Ω

V_ab = mV

4.Medium

A galvanometer with a resistance of 200 Ω is connected between a and b of the bridge shown (V_s = 15 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 15 VR₁ = 300 ΩR₂ = 250 ΩR₃ = 150 ΩR₄ = 20 ΩR_g = 200 Ω

I_g = µA

5.Hard

A bridge with 120 Ω arms is excited with 5 V and has one active gauge (quarter bridge). The gauge factor is 2 and the strain is 1000 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2ε = 1000 µε

V_o = mV

6.Hard

A quarter bridge (one active gauge, GF = 2.1) is excited with 5 V. The largest strain to be measured is 200 µε, and it must give 10 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 5 VGF = 2.1ε_max = 200 µεV_FS = 10 V

G =

Answer key

1. V_ab = −0.2857 V
2. V_ab = 3.667 V
3. V_ab = 90.91 mV
4. I_g = 14275 µA
5. V_o = 2.5 mV
6. G = 19048

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