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 = 2 V, R₁ = 80 Ω and R₂ = 500 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 2 VR₁ = 80 ΩR₂ = 500 ΩR₃ = 300 ΩR₄ = 200 Ω

V_a = V

2.Easy

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 600 Ω, R₂ = 60 Ω and R₄ = 80 Ω. Find the setting R₃.

R₁ = 600 ΩR₂ = 60 ΩR₄ = 80 Ω

R₃ = Ω

3.Medium

A galvanometer with a resistance of 50 Ω is connected between a and b of the bridge shown (V_s = 2 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 2 VR₁ = 10 ΩR₂ = 400 ΩR₃ = 50 ΩR₄ = 800 ΩR_g = 50 Ω

I_g = µA

4.Medium

A bridge with four 220 Ω arms is supplied with 12 V. When the sensor R₂ changes, the output reads V_ab = 285.7 mV. Find the exact change ΔR of R₂.

V_s = 12 VR = 220 ΩV_ab = 285.7 mV

ΔR = Ω

5.Hard

A quarter bridge with one active gauge (GF = 2.05) is excited with 3 V. Under load the output reads 1.23 mV. Find the strain ε in µε.

V_s = 3 VGF = 2.05V_o = 1.23 mV

ε = µε

6.Hard

A quarter bridge (one active gauge, GF = 2.05) is excited with 2.5 V. The largest strain to be measured is 1000 µε, and it must give 3.3 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 2.5 VGF = 2.05ε_max = 1000 µεV_FS = 3.3 V

G =

Answer key

1. V_a = 1.724 V
2. R₃ = 800 Ω
3. I_g = 644.7 µA
4. ΔR = 22 Ω
5. ε = 800 µε
6. G = 2576

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