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 = 120 Ω, R₂ = 100 Ω and R₄ = 10 Ω. Find the setting R₃.

R₁ = 120 ΩR₂ = 100 ΩR₄ = 10 Ω

R₃ = Ω

2.Easy

In the bridge shown, V_s = 5 V, R₁ = 20 Ω and R₂ = 80 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 5 VR₁ = 20 ΩR₂ = 80 ΩR₃ = 600 ΩR₄ = 600 Ω

V_a = V

3.Medium

A galvanometer with a resistance of 200 Ω is connected between a and b of the bridge shown (V_s = 2 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 2 VR₁ = 40 ΩR₂ = 40 ΩR₃ = 200 ΩR₄ = 100 ΩR_g = 200 Ω

I_g = µA

4.Medium

A bridge has four 220 Ω arms and V_s = 12 V. The sensor R₂ increases by ΔR = 0.55 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 12 VR = 220 ΩΔR = 0.55 Ω

V_ab = mV

5.Hard

A bridge with 1000 Ω arms is excited with 5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.12 and the strain is 750 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.12ε = 750 µε

V_o = mV

6.Hard

A 120 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 0.288 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2ΔR = 0.288 Ω

ε = µε

Answer key

1. R₃ = 12 Ω
2. V_a = 4 V
3. I_g = 1163 µA
4. V_ab = 7.5 mV
5. V_o = 3.975 mV
6. ε = 1200 µε

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