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

In the bridge shown, V_s = 12 V, R₁ = 500 Ω and R₂ = 10 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 12 VR₁ = 500 ΩR₂ = 10 ΩR₃ = 50 ΩR₄ = 400 Ω

V_a = V

2.Easy

In the bridge shown, V_s = 15 V, R₁ = 20 Ω and R₂ = 1000 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 15 VR₁ = 20 ΩR₂ = 1000 ΩR₃ = 300 ΩR₄ = 10 Ω

V_a = V

3.Medium

A bridge with four 150 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 = 150 ΩV_ab = 169.8 mV

ΔR = Ω

4.Medium

A galvanometer with a resistance of 50 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 = 600 ΩR₂ = 50 ΩR₃ = 60 ΩR₄ = 150 ΩR_g = 50 Ω

I_g = µA

5.Hard

A bridge with 1000 Ω arms is excited with 5 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2.12 and the strain is 800 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.12ε = 800 µε

V_o = mV

6.Hard

A bridge with 350 Ω arms is excited with 3 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 1500 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2.05ε = 1500 µε

V_o = mV

Answer key

1. V_a = 0.2353 V
2. V_a = 14.71 V
3. ΔR = 18 Ω
4. I_g = −9170 µA
5. V_o = 8.48 mV
6. V_o = 4.612 mV

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