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

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 9 V.

V_s = 9 VR₁ = 600 ΩR₂ = 40 ΩR₃ = 600 ΩR₄ = 20 Ω

V_ab = V

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 120 Ω, R₂ = 500 Ω and R₄ = 1000 Ω. Find the setting R₃.

R₁ = 120 ΩR₂ = 500 ΩR₄ = 1000 Ω

R₃ = Ω

3.Medium

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

V_s = 6 VR₁ = 60 ΩR₂ = 10 ΩR₃ = 1000 ΩR₄ = 600 Ω

R_th = Ω

4.Medium

A galvanometer with a resistance of 20 Ω is connected between a and b of the bridge shown (V_s = 6 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 6 VR₁ = 60 ΩR₂ = 1000 ΩR₃ = 20 ΩR₄ = 60 ΩR_g = 20 Ω

I_g = µA

5.Hard

A bridge with 120 Ω arms is excited with 10 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2 and the strain is 200 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2ε = 200 µε

V_o = mV

6.Hard

A bridge with 350 Ω arms is excited with 3 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.1 and the strain is 1500 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.1ε = 1500 µε

V_o = mV

Answer key

1. V_ab = 0.2722 V
2. R₃ = 240 Ω
3. R_th = 383.6 Ω
4. I_g = 12667 µA
5. V_o = 4 mV
6. V_o = 9.45 mV

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