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 = 20 Ω, R₂ = 10 Ω and R₄ = 120 Ω. Find the setting R₃.

R₁ = 20 ΩR₂ = 10 ΩR₄ = 120 Ω

R₃ = Ω

2.Easy

The bridge shown is supplied with V_s = 9 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 9 VR₁ = 100 ΩR₂ = 40 ΩR₃ = 120 ΩR₄ = 20 Ω

I_s = mA

3.Medium

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

V_s = 15 VR₁ = 80 ΩR₂ = 50 ΩR₃ = 600 ΩR₄ = 200 Ω

R_th = Ω

4.Medium

A galvanometer with a resistance of 100 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 = 50 ΩR₂ = 800 ΩR₃ = 60 ΩR₄ = 300 ΩR_g = 100 Ω

I_g = µA

5.Hard

A bridge with 350 Ω arms is excited with 2.5 V and has one active gauge (quarter bridge). The gauge factor is 2.1 and the strain is 250 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.1ε = 250 µε

V_o = mV

6.Hard

A bridge with 120 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 2.12 and the strain is 400 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.12ε = 400 µε

V_o = mV

Answer key

1. R₃ = 240 Ω
2. I_s = 128.6 mA
3. R_th = 180.8 Ω
4. I_g = 1642 µA
5. V_o = 0.3281 mV
6. V_o = 2.544 mV

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