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 = 120 Ω, R₂ = 300 Ω and R₄ = 100 Ω. Find the setting R₃.

R₁ = 120 ΩR₂ = 300 ΩR₄ = 100 Ω

R₃ = Ω

2.Easy

The bridge shown is supplied with V_s = 5 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 5 VR₁ = 600 ΩR₂ = 1000 ΩR₃ = 50 ΩR₄ = 120 Ω

I_s = mA

3.Medium

A bridge has four 1000 Ω arms and V_s = 2 V. The sensor R₂ increases by ΔR = 50 Ω. Find the exact output V_ab in mV.

V_s = 2 VR = 1000 ΩΔR = 50 Ω

V_ab = mV

4.Medium

A galvanometer with a resistance of 20 Ω is connected between a and b of the bridge shown (V_s = 2 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 2 VR₁ = 300 ΩR₂ = 300 ΩR₃ = 10 ΩR₄ = 250 ΩR_g = 20 Ω

I_g = µA

5.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 2.05 and the strain is 600 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.05ε = 600 µε

V_o = mV

6.Hard

A quarter bridge with one active gauge (GF = 2) is excited with 5 V. Under load the output reads 1.25 mV. Find the strain ε in µε.

V_s = 5 VGF = 2V_o = 1.25 mV

ε = µε

Answer key

1. R₃ = 40 Ω
2. I_s = 32.54 mA
3. V_ab = 24.39 mV
4. I_g = −5139 µA
5. V_o = 3.075 mV
6. ε = 500 µε

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