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 = 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 = 800 ΩR₄ = 50 Ω

V_a = V

2.Easy

The bridge shown is supplied with V_s = 2 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 2 VR₁ = 80 ΩR₂ = 50 ΩR₃ = 500 ΩR₄ = 60 Ω

I_s = mA

3.Medium

A bridge has four 150 Ω arms and V_s = 3 V. The sensor R₂ increases by ΔR = 0.6 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 3 VR = 150 ΩΔR = 0.6 Ω

V_ab = mV

4.Medium

A bridge has four 400 Ω arms and V_s = 3 V. The sensor R₂ increases by ΔR = 80 Ω. Find the exact output V_ab in mV.

V_s = 3 VR = 400 ΩΔR = 80 Ω

V_ab = mV

5.Hard

A 120 Ω strain gauge with gauge factor 2.1 is bonded to a steel bar. Under load its resistance rises by 0.1008 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2.1ΔR = 0.1008 Ω

ε = µε

6.Hard

A quarter bridge with one active gauge (GF = 2.05) is excited with 10 V. Under load the output reads 1.281 mV. Find the strain ε in µε.

V_s = 10 VGF = 2.05V_o = 1.281 mV

ε = µε

Answer key

1. V_a = 1.2 V
2. I_s = 18.96 mA
3. V_ab = 3 mV
4. V_ab = 136.4 mV
5. ε = 400 µε
6. ε = 250 µε

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