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: the galvanometer reads zero. R₁ = 250 Ω, R₂ = 300 Ω and R₃ = 500 Ω. Find the unknown resistor R₄.

R₁ = 250 ΩR₂ = 300 ΩR₃ = 500 Ω

R₄ = Ω

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 300 Ω, R₂ = 300 Ω and R₄ = 100 Ω. Find the setting R₃.

R₁ = 300 ΩR₂ = 300 ΩR₄ = 100 Ω

R₃ = Ω

3.Medium

A bridge has four 330 Ω arms and V_s = 3 V. The sensor R₂ increases by ΔR = 49.5 Ω. Find the exact output V_ab in mV.

V_s = 3 VR = 330 ΩΔR = 49.5 Ω

V_ab = mV

4.Medium

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

V_s = 5 VR₁ = 60 ΩR₂ = 500 ΩR₃ = 120 ΩR₄ = 150 Ω

R_th = Ω

5.Hard

A bridge with 1000 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 1000 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.1ε = 1000 µε

V_o = mV

6.Hard

A 120 Ω strain gauge with gauge factor 2.05 is bonded to a steel bar. Under load its resistance rises by 0.0492 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2.05ΔR = 0.0492 Ω

ε = µε

Answer key

1. R₄ = 600 Ω
2. R₃ = 100 Ω
3. V_ab = 104.7 mV
4. R_th = 120.2 Ω
5. V_o = 1.313 mV
6. ε = 200 µε

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