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 = 5 V, R₁ = 120 Ω and R₂ = 50 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 5 VR₁ = 120 ΩR₂ = 50 ΩR₃ = 1000 ΩR₄ = 200 Ω

V_a = V

2.Easy

Find the open-circuit output voltage V_ab = V_a − V_b of the bridge shown, with V_s = 9 V.

V_s = 9 VR₁ = 10 ΩR₂ = 40 ΩR₃ = 40 ΩR₄ = 1000 Ω

V_ab = V

3.Medium

A bridge has four 400 Ω arms and V_s = 3 V. The sensor R₂ increases by ΔR = 40 Ω. Find the exact output V_ab in mV.

V_s = 3 VR = 400 ΩΔR = 40 Ω

V_ab = mV

4.Medium

A bridge has four 220 Ω arms and V_s = 5 V. The sensor R₂ increases by ΔR = 22 Ω. Find the exact output V_ab in mV.

V_s = 5 VR = 220 ΩΔR = 22 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 10 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 = 10 V

G =

6.Hard

A bridge with 1000 Ω arms is excited with 5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2 and the strain is 600 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2ε = 600 µε

V_o = mV

Answer key

1. V_a = 1.471 V
2. V_ab = −1.454 V
3. V_ab = 71.43 mV
4. V_ab = 119 mV
5. G = 40000
6. V_o = 3 mV

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