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 = 2 V, R₁ = 250 Ω and R₂ = 100 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 2 VR₁ = 250 ΩR₂ = 100 ΩR₃ = 250 ΩR₄ = 600 Ω

V_a = V

2.Easy

The bridge shown is supplied with V_s = 6 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 6 VR₁ = 500 ΩR₂ = 300 ΩR₃ = 300 ΩR₄ = 300 Ω

I_s = mA

3.Medium

A bridge with four 200 Ω arms is supplied with 6 V. When the sensor R₂ changes, the output reads V_ab = 115.4 mV. Find the exact change ΔR of R₂.

V_s = 6 VR = 200 ΩV_ab = 115.4 mV

ΔR = Ω

4.Medium

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

V_s = 2 VR₁ = 120 ΩR₂ = 100 ΩR₃ = 80 ΩR₄ = 40 Ω

R_th = Ω

5.Hard

A 1000 Ω strain gauge with gauge factor 2.05 is bonded to a steel bar. Under load its resistance rises by 2.46 Ω. Find the strain ε in microstrain (µε).

R = 1000 ΩGF = 2.05ΔR = 2.46 Ω

ε = µε

6.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 2.5 V. The largest strain to be measured is 1200 µε, and it must give 3.3 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 2.5 VGF = 2ε_max = 1200 µεV_FS = 3.3 V

G =

Answer key

1. V_a = 0.5714 V
2. I_s = 17.5 mA
3. ΔR = 16 Ω
4. R_th = 81.21 Ω
5. ε = 1200 µε
6. G = 2200

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