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 = 12 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 12 VR₁ = 80 ΩR₂ = 150 ΩR₃ = 120 ΩR₄ = 60 Ω

I_s = mA

2.Easy

In the bridge shown, V_s = 3 V, R₁ = 400 Ω and R₂ = 50 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 3 VR₁ = 400 ΩR₂ = 50 ΩR₃ = 20 ΩR₄ = 60 Ω

V_a = V

3.Medium

A bridge has four 200 Ω arms and V_s = 10 V. The sensor R₂ increases by ΔR = 40 Ω. Find the exact output V_ab in mV.

V_s = 10 VR = 200 ΩΔR = 40 Ω

V_ab = mV

4.Medium

A bridge with four 350 Ω arms is supplied with 6 V. When the sensor R₂ changes, the output reads V_ab = 169.8 mV. Find the exact change ΔR of R₂.

V_s = 6 VR = 350 ΩV_ab = 169.8 mV

ΔR = Ω

5.Hard

A bridge with 120 Ω arms is excited with 3 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2 and the strain is 250 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2ε = 250 µε

V_o = mV

6.Hard

A bridge with 1000 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 2.12 and the strain is 1000 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.12ε = 1000 µε

V_o = mV

Answer key

1. I_s = 118.8 mA
2. V_a = 0.3333 V
3. V_ab = 454.5 mV
4. ΔR = 42 Ω
5. V_o = 1.5 mV
6. V_o = 2.65 mV

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