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 = 80 ΩR₂ = 100 ΩR₃ = 600 ΩR₄ = 250 Ω

I_s = mA

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 = 50 ΩR₂ = 200 ΩR₃ = 250 ΩR₄ = 600 Ω

I_s = mA

3.Medium

A bridge has four 120 Ω arms and V_s = 10 V. The sensor R₂ increases by ΔR = 0.24 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 10 VR = 120 ΩΔR = 0.24 Ω

V_ab = mV

4.Medium

A galvanometer with a resistance of 100 Ω is connected between a and b of the bridge shown (V_s = 9 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 9 VR₁ = 250 ΩR₂ = 200 ΩR₃ = 250 ΩR₄ = 40 ΩR_g = 100 Ω

I_g = µA

5.Hard

A quarter bridge with one active gauge (GF = 2.1) is excited with 2.5 V. Under load the output reads 0.787 mV. Find the strain ε in µε.

V_s = 2.5 VGF = 2.1V_o = 0.787 mV

ε = µε

6.Hard

A 350 Ω strain gauge with gauge factor 2.1 is bonded to a steel bar. Under load its resistance rises by 0.147 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2.1ΔR = 0.147 Ω

ε = µε

Answer key

1. I_s = 101 mA
2. I_s = 51.76 mA
3. V_ab = 5 mV
4. I_g = 11232 µA
5. ε = 599.6 µε
6. ε = 200 µε

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