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 = 60 Ω, R₂ = 60 Ω and R₄ = 150 Ω. Find the setting R₃.

R₁ = 60 ΩR₂ = 60 ΩR₄ = 150 Ω

R₃ = Ω

2.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 = 80 ΩR₂ = 10 ΩR₃ = 120 ΩR₄ = 600 Ω

I_s = mA

3.Medium

A 500 Ω strain gauge is one arm (R₂) of a bridge with four equal 500 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 = 500 Ω

P_g = mW

4.Medium

A 400 Ω strain gauge is one arm (R₂) of a bridge with four equal 400 Ω arms and an excitation of 2 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 2 VR = 400 Ω

P_g = mW

5.Hard

A 120 Ω strain gauge with gauge factor 2.12 is bonded to a steel bar. Under load its resistance rises by 0.2035 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2.12ΔR = 0.2035 Ω

ε = µε

6.Hard

A bridge with 120 Ω arms is excited with 2.5 V and has two active gauges in adjacent arms, one in tension and one in compression (half 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

Answer key

1. R₃ = 150 Ω
2. I_s = 25 mA
3. P_g = 50 mW
4. P_g = 2.5 mW
5. ε = 800 µε
6. V_o = 0.5 mV

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