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 = 12 V, R₁ = 60 Ω and R₂ = 800 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 12 VR₁ = 60 ΩR₂ = 800 ΩR₃ = 800 ΩR₄ = 300 Ω

V_a = V

2.Easy

The Wheatstone bridge in the diagram is balanced: the galvanometer reads zero. R₁ = 100 Ω, R₂ = 200 Ω and R₃ = 20 Ω. Find the unknown resistor R₄.

R₁ = 100 ΩR₂ = 200 ΩR₃ = 20 Ω

R₄ = Ω

3.Medium

A bridge with four 300 Ω arms is supplied with 15 V. When the sensor R₂ changes, the output reads V_ab = 182.9 mV. Find the exact change ΔR of R₂.

V_s = 15 VR = 300 ΩV_ab = 182.9 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 = 10 VR₁ = 250 ΩR₂ = 600 ΩR₃ = 100 ΩR₄ = 200 Ω

R_th = Ω

5.Hard

A bridge with 350 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 2.1 and the strain is 1200 µε. Find the bridge output V_o in mV.

V_s = 2.5 VGF = 2.1ε = 1200 µε

V_o = mV

6.Hard

A bridge with 350 Ω arms is excited with 3 V and has four active gauges, two in tension and two in compression (full bridge). The gauge factor is 2 and the strain is 800 µε. Find the bridge output V_o in mV.

V_s = 3 VGF = 2ε = 800 µε

V_o = mV

Answer key

1. V_a = 11.16 V
2. R₄ = 40 Ω
3. ΔR = 15 Ω
4. R_th = 243.1 Ω
5. V_o = 6.3 mV
6. V_o = 4.8 mV

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