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

In the bridge shown, V_s = 9 V, R₁ = 120 Ω and R₂ = 250 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 9 VR₁ = 120 ΩR₂ = 250 ΩR₃ = 10 ΩR₄ = 20 Ω

V_a = V

2.Easy

The bridge shown is supplied with V_s = 9 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 9 VR₁ = 500 ΩR₂ = 60 ΩR₃ = 60 ΩR₄ = 40 Ω

I_s = mA

3.Medium

A bridge has four 400 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 1.6 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 9 VR = 400 ΩΔR = 1.6 Ω

V_ab = mV

4.Medium

A bridge has four 470 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 3.76 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 9 VR = 470 ΩΔR = 3.76 Ω

V_ab = mV

5.Hard

A quarter bridge with one active gauge (GF = 2) is excited with 2.5 V. Under load the output reads 1.5 mV. Find the strain ε in µε.

V_s = 2.5 VGF = 2V_o = 1.5 mV

ε = µε

6.Hard

A 120 Ω strain gauge with gauge factor 2.12 is bonded to a steel bar. Under load its resistance rises by 0.1908 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2.12ΔR = 0.1908 Ω

ε = µε

Answer key

1. V_a = 6.081 V
2. I_s = 106.1 mA
3. V_ab = 9 mV
4. V_ab = 18 mV
5. ε = 1200 µε
6. ε = 750 µε

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