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 = 80 Ω, R₂ = 10 Ω and R₄ = 80 Ω. Find the setting R₃.

R₁ = 80 ΩR₂ = 10 ΩR₄ = 80 Ω

R₃ = Ω

2.Easy

The bridge shown is supplied with V_s = 12 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 12 VR₁ = 400 ΩR₂ = 50 ΩR₃ = 50 ΩR₄ = 120 Ω

I_s = mA

3.Medium

A 300 Ω strain gauge is one arm (R₂) of a bridge with four equal 300 Ω arms and an excitation of 5 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 5 VR = 300 Ω

P_g = mW

4.Medium

A galvanometer with a resistance of 20 Ω is connected between a and b of the bridge shown (V_s = 3 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 3 VR₁ = 40 ΩR₂ = 400 ΩR₃ = 600 ΩR₄ = 60 ΩR_g = 20 Ω

I_g = µA

5.Hard

A bridge with 350 Ω arms is excited with 10 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.12 and the strain is 750 µε. Find the bridge output V_o in mV.

V_s = 10 VGF = 2.12ε = 750 µε

V_o = mV

6.Hard

A bridge with 120 Ω arms is excited with 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 1200 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2ε = 1200 µε

V_o = mV

Answer key

1. R₃ = 640 Ω
2. I_s = 97.25 mA
3. P_g = 20.83 mW
4. I_g = 22131 µA
5. V_o = 7.95 mV
6. V_o = 6 mV

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