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 Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 200 Ω, R₂ = 400 Ω and R₄ = 10 Ω. Find the setting R₃.

R₁ = 200 ΩR₂ = 400 ΩR₄ = 10 Ω

R₃ = Ω

2.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 6 V.

V_s = 6 VR₁ = 60 ΩR₂ = 100 ΩR₃ = 400 ΩR₄ = 400 Ω

V_ab = V

3.Medium

Find the Thévenin resistance R_th of the bridge shown, seen from the output terminals a and b.

V_s = 12 VR₁ = 80 ΩR₂ = 80 ΩR₃ = 250 ΩR₄ = 500 Ω

R_th = Ω

4.Medium

A galvanometer with a resistance of 500 Ω is connected between a and b of the bridge shown (V_s = 12 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 12 VR₁ = 80 ΩR₂ = 250 ΩR₃ = 800 ΩR₄ = 80 ΩR_g = 500 Ω

I_g = µA

5.Hard

A 120 Ω strain gauge with gauge factor 2.05 is bonded to a steel bar. Under load its resistance rises by 0.2952 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2.05ΔR = 0.2952 Ω

ε = µε

6.Hard

A 120 Ω strain gauge with gauge factor 2.05 is bonded to a steel bar. Under load its resistance rises by 0.123 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2.05ΔR = 0.123 Ω

ε = µε

Answer key

1. R₃ = 5 Ω
2. V_ab = 0.75 V
3. R_th = 206.7 Ω
4. I_g = 12632 µA
5. ε = 1200 µε
6. ε = 500 µε

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