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 = 9 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 9 VR₁ = 50 ΩR₂ = 800 ΩR₃ = 500 ΩR₄ = 80 Ω

I_s = mA

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 600 Ω, R₂ = 400 Ω and R₄ = 400 Ω. Find the setting R₃.

R₁ = 600 ΩR₂ = 400 ΩR₄ = 400 Ω

R₃ = Ω

3.Medium

A 400 Ω strain gauge is one arm (R₂) of a bridge with four equal 400 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 = 400 Ω

P_g = mW

4.Medium

A bridge has four 1000 Ω arms and V_s = 6 V. The sensor R₂ increases by ΔR = 2 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 6 VR = 1000 ΩΔR = 2 Ω

V_ab = mV

5.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 2.5 V. The largest strain to be measured is 200 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 2.5 VGF = 2ε_max = 200 µεV_FS = 5 V

G =

6.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 2.5 V. The largest strain to be measured is 1000 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 2.5 VGF = 2ε_max = 1000 µεV_FS = 5 V

G =

Answer key

1. I_s = 26.11 mA
2. R₃ = 600 Ω
3. P_g = 62.5 mW
4. V_ab = 3 mV
5. G = 20000
6. G = 4000

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