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 bridge shown is supplied with V_s = 2 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 2 VR₁ = 500 ΩR₂ = 500 ΩR₃ = 400 ΩR₄ = 800 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 80 Ω, R₂ = 250 Ω and R₃ = 300 Ω. Find the unknown resistor R₄.

R₁ = 80 ΩR₂ = 250 ΩR₃ = 300 Ω

R₄ = Ω

3.Medium

A bridge with four 300 Ω arms is supplied with 15 V. When the sensor R₂ changes, the output reads V_ab = 147.1 mV. Find the exact change ΔR of R₂.

V_s = 15 VR = 300 ΩV_ab = 147.1 mV

ΔR = Ω

4.Medium

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

V_s = 12 VR₁ = 10 ΩR₂ = 50 ΩR₃ = 60 ΩR₄ = 250 Ω

R_th = Ω

5.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 and the strain is 750 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2ε = 750 µε

V_o = mV

6.Hard

A bridge with 350 Ω arms is excited with 3 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.1 and the strain is 1200 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.1ε = 1200 µε

V_o = mV

Answer key

1. I_s = 3.667 mA
2. R₄ = 937.5 Ω
3. ΔR = 12 Ω
4. R_th = 56.72 Ω
5. V_o = 4.5 mV
6. V_o = 3.78 mV

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