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 = 15 V, R₁ = 250 Ω and R₂ = 80 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 15 VR₁ = 250 ΩR₂ = 80 ΩR₃ = 150 ΩR₄ = 120 Ω

V_a = V

2.Easy

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 600 Ω, R₂ = 200 Ω and R₃ = 300 Ω. Find the unknown resistor R₄.

R₁ = 600 ΩR₂ = 200 ΩR₃ = 300 Ω

R₄ = Ω

3.Medium

A bridge has four 120 Ω arms and V_s = 5 V. The sensor R₂ increases by ΔR = 0.6 Ω. Using the small-change approximation, find the output V_ab in mV.

V_s = 5 VR = 120 ΩΔR = 0.6 Ω

V_ab = mV

4.Medium

A bridge with four 1000 Ω arms is supplied with 5 V. When the sensor R₂ changes, the output reads V_ab = 60.98 mV. Find the exact change ΔR of R₂.

V_s = 5 VR = 1000 ΩV_ab = 60.98 mV

ΔR = Ω

5.Hard

A bridge with 120 Ω arms is excited with 2.5 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2 and the strain is 1500 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2ε = 1500 µε

V_o = mV

6.Hard

A 350 Ω strain gauge with gauge factor 2 is bonded to a steel bar. Under load its resistance rises by 0.7 Ω. Find the strain ε in microstrain (µε).

R = 350 ΩGF = 2ΔR = 0.7 Ω

ε = µε

Answer key

1. V_a = 3.636 V
2. R₄ = 100 Ω
3. V_ab = 6.25 mV
4. ΔR = 50 Ω
5. V_o = 7.5 mV
6. ε = 1000 µε

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