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 = 20 Ω and R₂ = 150 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 5 VR₁ = 20 ΩR₂ = 150 ΩR₃ = 400 ΩR₄ = 250 Ω

V_a = V

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 120 Ω, R₂ = 300 Ω and R₄ = 400 Ω. Find the setting R₃.

R₁ = 120 ΩR₂ = 300 ΩR₄ = 400 Ω

R₃ = Ω

3.Medium

A bridge with four 120 Ω arms is supplied with 3 V. When the sensor R₂ changes, the output reads V_ab = 29.41 mV. Find the exact change ΔR of R₂.

V_s = 3 VR = 120 ΩV_ab = 29.41 mV

ΔR = Ω

4.Medium

A 120 Ω strain gauge is one arm (R₂) of a bridge with four equal 120 Ω arms and an excitation of 3 V. Find the power P_g dissipated in the gauge, in mW. Self-heating limits the excitation.

V_s = 3 VR = 120 Ω

P_g = mW

5.Hard

A bridge with 120 Ω arms is excited with 5 V and has one active gauge (quarter bridge). The gauge factor is 2.1 and the strain is 600 µε. Find the bridge output V_o in mV.

V_s = 5 VGF = 2.1ε = 600 µε

V_o = mV

6.Hard

A quarter bridge with one active gauge (GF = 2.05) is excited with 2.5 V. Under load the output reads 1.025 mV. Find the strain ε in µε.

V_s = 2.5 VGF = 2.05V_o = 1.025 mV

ε = µε

Answer key

1. V_a = 4.412 V
2. R₃ = 160 Ω
3. ΔR = 4.8 Ω
4. P_g = 18.75 mW
5. V_o = 1.575 mV
6. ε = 800 µε

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