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 = 6 V, R₁ = 800 Ω and R₂ = 800 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 6 VR₁ = 800 ΩR₂ = 800 ΩR₃ = 250 ΩR₄ = 10 Ω

V_a = V

2.Easy

In the bridge shown, V_s = 6 V, R₁ = 60 Ω and R₂ = 60 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 6 VR₁ = 60 ΩR₂ = 60 ΩR₃ = 60 ΩR₄ = 800 Ω

V_a = V

3.Medium

A bridge has four 120 Ω arms and V_s = 10 V. The sensor R₂ increases by ΔR = 0.12 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 10 VR = 120 ΩΔR = 0.12 Ω

V_ab = mV

4.Medium

A bridge has four 120 Ω arms and V_s = 2 V. The sensor R₂ increases by ΔR = 12 Ω. Find the exact output V_ab in mV.

V_s = 2 VR = 120 ΩΔR = 12 Ω

V_ab = mV

5.Hard

A load cell (a full bridge of strain gauges) has a rated output of 2.5 mV/V at its rated load of 100 kg. It is excited with 12 V. Find its output V_o under a load of 40 kg.

2.5 mV/VF_rated = 100 kgV_s = 12 VF = 40 kg

V_o = mV

6.Hard

A bridge with 350 Ω arms is excited with 2.5 V and has one active gauge (quarter bridge). The gauge factor is 2.1 and the strain is 500 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.1ε = 500 µε

V_o = mV

Answer key

1. V_a = 3 V
2. V_a = 3 V
3. V_ab = 2.5 mV
4. V_ab = 47.62 mV
5. V_o = 12 mV
6. V_o = 0.6563 mV

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