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

The Wheatstone bridge in the diagram is balanced by adjusting R₃. R₁ = 60 Ω, R₂ = 80 Ω and R₄ = 50 Ω. Find the setting R₃.

R₁ = 60 ΩR₂ = 80 ΩR₄ = 50 Ω

R₃ = Ω

2.Easy

In the bridge shown, V_s = 3 V, R₁ = 600 Ω and R₂ = 60 Ω. Find the voltage V_a of node a with respect to the negative supply rail.

V_s = 3 VR₁ = 600 ΩR₂ = 60 ΩR₃ = 40 ΩR₄ = 1000 Ω

V_a = V

3.Medium

A bridge with four 100 Ω arms is supplied with 2 V. When the sensor R₂ changes, the output reads V_ab = 24.39 mV. Find the exact change ΔR of R₂.

V_s = 2 VR = 100 ΩV_ab = 24.39 mV

ΔR = Ω

4.Medium

A galvanometer with a resistance of 200 Ω is connected between a and b of the bridge shown (V_s = 5 V). Find the galvanometer current I_g from a to b, in µA.

V_s = 5 VR₁ = 1000 ΩR₂ = 500 ΩR₃ = 800 ΩR₄ = 10 ΩR_g = 200 Ω

I_g = µA

5.Hard

A quarter bridge (one active gauge, GF = 2) is excited with 3 V. The largest strain to be measured is 1500 µε, and it must give 10 V at the input of an analogue-to-digital converter. Find the amplifier gain G.

V_s = 3 VGF = 2ε_max = 1500 µεV_FS = 10 V

G =

6.Hard

A bridge with 1000 Ω arms is excited with 2.5 V and has one active gauge (quarter 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

Answer key

1. R₃ = 37.5 Ω
2. V_a = 0.2727 V
3. ΔR = 5 Ω
4. I_g = 2955 µA
5. G = 4444
6. V_o = 1.875 mV

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