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 = 9 V, R₁ = 80 Ω and R₂ = 150 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 9 VR₁ = 80 ΩR₂ = 150 ΩR₃ = 600 ΩR₄ = 20 Ω

V_a = V

2.Easy

In the bridge shown, V_s = 10 V, R₁ = 500 Ω and R₂ = 40 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 10 VR₁ = 500 ΩR₂ = 40 ΩR₃ = 10 ΩR₄ = 40 Ω

V_a = V

3.Medium

A bridge has four 120 Ω arms and V_s = 12 V. The sensor R₂ increases by ΔR = 0.24 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 12 VR = 120 ΩΔR = 0.24 Ω

V_ab = mV

4.Medium

Find the Thévenin resistance R_th of the bridge shown, seen from the output terminals a and b.

V_s = 10 VR₁ = 200 ΩR₂ = 200 ΩR₃ = 150 ΩR₄ = 20 Ω

R_th = Ω

5.Hard

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

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

G =

6.Hard

A bridge with 120 Ω arms is excited with 2.5 V and has one active gauge (quarter bridge). The gauge factor is 2 and the strain is 200 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2ε = 200 µε

V_o = mV

Answer key

1. V_a = 5.87 V
2. V_a = 0.7407 V
3. V_ab = 6 mV
4. R_th = 117.6 Ω
5. G = 5000
6. V_o = 0.25 mV

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