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 = 300 Ω and R₂ = 10 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 5 VR₁ = 300 ΩR₂ = 10 ΩR₃ = 50 ΩR₄ = 50 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 = 12 V.

V_s = 12 VR₁ = 200 ΩR₂ = 40 ΩR₃ = 40 ΩR₄ = 60 Ω

V_ab = V

3.Medium

A bridge with four 200 Ω arms is supplied with 15 V. When the sensor R₂ changes, the output reads V_ab = 37.31 mV. Find the exact change ΔR of R₂.

V_s = 15 VR = 200 ΩV_ab = 37.31 mV

ΔR = Ω

4.Medium

A 220 Ω strain gauge is one arm (R₂) of a bridge with four equal 220 Ω arms and an excitation of 6 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 6 VR = 220 Ω

P_g = mW

5.Hard

A bridge with 1000 Ω arms is excited with 2.5 V and has two active gauges in adjacent arms, one in tension and one in compression (half bridge). The gauge factor is 2.12 and the strain is 600 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.12ε = 600 µε

V_o = mV

6.Hard

A 120 Ω strain gauge with gauge factor 2.12 is bonded to a steel bar. Under load its resistance rises by 0.05088 Ω. Find the strain ε in microstrain (µε).

R = 120 ΩGF = 2.12ΔR = 0.05088 Ω

ε = µε

Answer key

1. V_a = 0.1613 V
2. V_ab = −5.2 V
3. ΔR = 2 Ω
4. P_g = 40.91 mW
5. V_o = 1.59 mV
6. ε = 200 µε

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