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 = 10 V, R₁ = 800 Ω and R₂ = 1000 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 10 VR₁ = 800 ΩR₂ = 1000 ΩR₃ = 50 ΩR₄ = 20 Ω

V_a = V

2.Easy

The bridge shown is supplied with V_s = 5 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 5 VR₁ = 800 ΩR₂ = 800 ΩR₃ = 200 ΩR₄ = 80 Ω

I_s = mA

3.Medium

A bridge with four 400 Ω arms is supplied with 2 V. When the sensor R₂ changes, the output reads V_ab = 38.46 mV. Find the exact change ΔR of R₂.

V_s = 2 VR = 400 ΩV_ab = 38.46 mV

ΔR = Ω

4.Medium

A bridge with four 400 Ω arms is supplied with 10 V. When the sensor R₂ changes, the output reads V_ab = 192.3 mV. Find the exact change ΔR of R₂.

V_s = 10 VR = 400 ΩV_ab = 192.3 mV

ΔR = Ω

5.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 3 V. The largest strain to be measured is 200 µε, and it must give 3.3 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 3 VGF = 2ε_max = 200 µεV_FS = 3.3 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 250 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2ε = 250 µε

V_o = mV

Answer key

1. V_a = 5.556 V
2. I_s = 20.98 mA
3. ΔR = 32 Ω
4. ΔR = 32 Ω
5. G = 11000
6. V_o = 0.3125 mV

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