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 bridge shown is supplied with V_s = 3 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 3 VR₁ = 150 ΩR₂ = 200 ΩR₃ = 600 ΩR₄ = 300 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 200 Ω, R₂ = 500 Ω and R₄ = 100 Ω. Find the setting R₃.

R₁ = 200 ΩR₂ = 500 ΩR₄ = 100 Ω

R₃ = Ω

3.Medium

A 120 Ω strain gauge is one arm (R₂) of a bridge with four equal 120 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 = 120 Ω

P_g = mW

4.Medium

A galvanometer with a resistance of 500 Ω is connected between a and b of the bridge shown (V_s = 6 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 6 VR₁ = 120 ΩR₂ = 500 ΩR₃ = 60 ΩR₄ = 120 ΩR_g = 500 Ω

I_g = µA

5.Hard

A bridge with 350 Ω arms is excited with 3 V and has one active gauge (quarter bridge). The gauge factor is 2.12 and the strain is 250 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.12ε = 250 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 0.288 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2ΔR = 0.288 Ω

ε = µε

Answer key

1. I_s = 11.9 mA
2. R₃ = 40 Ω
3. P_g = 8.333 mW
4. I_g = 1317 µA
5. V_o = 0.3975 mV
6. ε = 1200 µε

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