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 = 3 V, R₁ = 1000 Ω and R₂ = 600 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 3 VR₁ = 1000 ΩR₂ = 600 ΩR₃ = 500 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 = 6 V.

V_s = 6 VR₁ = 500 ΩR₂ = 20 ΩR₃ = 1000 ΩR₄ = 150 Ω

V_ab = V

3.Medium

A bridge has four 100 Ω arms and V_s = 15 V. The sensor R₂ increases by ΔR = 10 Ω. Find the exact output V_ab in mV.

V_s = 15 VR = 100 ΩΔR = 10 Ω

V_ab = mV

4.Medium

A bridge with four 250 Ω arms is supplied with 2 V. When the sensor R₂ changes, the output reads V_ab = 47.62 mV. Find the exact change ΔR of R₂.

V_s = 2 VR = 250 ΩV_ab = 47.62 mV

ΔR = Ω

5.Hard

A bridge with 120 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 and the strain is 750 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2ε = 750 µε

V_o = mV

6.Hard

A quarter bridge (one active gauge, GF = 2.05) is excited with 5 V. The largest strain to be measured is 500 µε, and it must give 5 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 5 VGF = 2.05ε_max = 500 µεV_FS = 5 V

G =

Answer key

1. V_a = 1.125 V
2. V_ab = −0.5518 V
3. V_ab = 357.1 mV
4. ΔR = 25 Ω
5. V_o = 7.5 mV
6. G = 3902

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