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

In a slide-wire (metre) bridge a known 100 Ω resistor sits in the left gap and an unknown resistor Rₓ in the right gap. The galvanometer reads zero when the jockey is 60 cm from the left end A of the 100 cm wire. Find R_x.

R = 100 Ωl = 60 cmL = 100 cm

R_x = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 800 Ω, R₂ = 250 Ω and R₄ = 200 Ω. Find the setting R₃.

R₁ = 800 ΩR₂ = 250 ΩR₄ = 200 Ω

R₃ = Ω

3.Medium

A bridge has four 350 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 17.5 Ω. Find the exact output V_ab in mV.

V_s = 9 VR = 350 ΩΔR = 17.5 Ω

V_ab = mV

4.Medium

A bridge has four 300 Ω arms and V_s = 9 V. The sensor R₂ increases by ΔR = 60 Ω. Find the exact output V_ab in mV.

V_s = 9 VR = 300 ΩΔR = 60 Ω

V_ab = mV

5.Hard

A bridge with 120 Ω arms is excited with 5 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 1500 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.12ε = 1500 µε

V_o = mV

6.Hard

A 350 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 1.05 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2ΔR = 1.05 Ω

ε = µε

Answer key

1. R_x = 66.67 Ω
2. R₃ = 640 Ω
3. V_ab = 109.8 mV
4. V_ab = 409.1 mV
5. V_o = 15.9 mV
6. ε = 1500 µε

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