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 = 150 Ω and R₂ = 300 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 3 VR₁ = 150 ΩR₂ = 300 ΩR₃ = 150 ΩR₄ = 400 Ω

V_a = V

2.Easy

The bridge shown is supplied with V_s = 2 V and its output is open. Find the current I_s drawn from the supply, in mA.

V_s = 2 VR₁ = 40 ΩR₂ = 500 ΩR₃ = 250 ΩR₄ = 600 Ω

I_s = mA

3.Medium

A bridge with four 120 Ω arms is supplied with 10 V. When the sensor R₂ changes, the output reads V_ab = 24.88 mV. Find the exact change ΔR of R₂.

V_s = 10 VR = 120 ΩV_ab = 24.88 mV

ΔR = Ω

4.Medium

A galvanometer with a resistance of 500 Ω is connected between a and b of the bridge shown (V_s = 12 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 12 VR₁ = 1000 ΩR₂ = 120 ΩR₃ = 80 ΩR₄ = 400 ΩR_g = 500 Ω

I_g = µA

5.Hard

A 120 Ω strain gauge with gauge factor 2.05 is bonded to a steel bar. Under load its resistance rises by 0.1476 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2.05ΔR = 0.1476 Ω

ε = µε

6.Hard

A 120 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 0.048 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2ΔR = 0.048 Ω

ε = µε

Answer key

1. V_a = 2 V
2. I_s = 6.057 mA
3. ΔR = 1.2 Ω
4. I_g = −12933 µA
5. ε = 600 µε
6. ε = 200 µε

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