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 = 10 V.

V_s = 10 VR₁ = 300 ΩR₂ = 120 ΩR₃ = 120 ΩR₄ = 250 Ω

V_ab = V

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 500 Ω, R₂ = 1000 Ω and R₄ = 600 Ω. Find the setting R₃.

R₁ = 500 ΩR₂ = 1000 ΩR₄ = 600 Ω

R₃ = Ω

3.Medium

A 100 Ω strain gauge is one arm (R₂) of a bridge with four equal 100 Ω arms and an excitation of 10 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 10 VR = 100 Ω

P_g = mW

4.Medium

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

V_s = 10 VR₁ = 300 ΩR₂ = 50 ΩR₃ = 10 ΩR₄ = 1000 Ω

R_th = Ω

5.Hard

A bridge with 120 Ω arms is excited with 2.5 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 = 2.5 VGF = 2ε = 200 µε

V_o = mV

6.Hard

A 120 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 0.36 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2ΔR = 0.36 Ω

ε = µε

Answer key

1. V_ab = −3.9 V
2. R₃ = 300 Ω
3. P_g = 250 mW
4. R_th = 52.76 Ω
5. V_o = 1 mV
6. ε = 1500 µε

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