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 = 12 V, R₁ = 50 Ω and R₂ = 400 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 12 VR₁ = 50 ΩR₂ = 400 ΩR₃ = 1000 ΩR₄ = 250 Ω

V_a = V

2.Easy

In the bridge shown, V_s = 5 V, R₁ = 200 Ω and R₂ = 120 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 5 VR₁ = 200 ΩR₂ = 120 ΩR₃ = 10 ΩR₄ = 600 Ω

V_a = V

3.Medium

A galvanometer with a resistance of 20 Ω is connected between a and b of the bridge shown (V_s = 3 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 3 VR₁ = 120 ΩR₂ = 200 ΩR₃ = 100 ΩR₄ = 300 ΩR_g = 20 Ω

I_g = µA

4.Medium

A bridge has four 500 Ω arms and V_s = 10 V. The sensor R₂ increases by ΔR = 4 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 10 VR = 500 ΩΔR = 4 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 0.5 mV. Find the strain ε in µε.

V_s = 2.5 VGF = 2V_o = 0.5 mV

ε = µε

6.Hard

A 350 Ω strain gauge with gauge factor 2.05 is bonded to a steel bar. Under load its resistance rises by 0.574 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2.05ΔR = 0.574 Ω

ε = µε

Answer key

1. V_a = 10.67 V
2. V_a = 1.875 V
3. I_g = −2206 µA
4. V_ab = 20 mV
5. ε = 400 µε
6. ε = 800 µε

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