Calculate the resistance of an aluminium cable of length 10 km and diameter 2.0 mm if the resistivity of aluminium is 27 × 10−8 Ωm.
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Solution
Length of the cable wire, l = 10 km = 10000 m
Diameter of the cable wire, d = 2.0 mm
Radius of the cable wire, r = 0.1 mm = 0.0001 m = 10-4 m
Area of cross-section, `A=Api^2` 3.14 × 10-8 m2
Resistivity of the aluminium cable wire = 27 × 10−8 Ω m.
Let the resistance of the aluminium cable be R.
We know that `R=l/A`
R=P/A
`R=27xx10-8xx103.14xx10-8`
`R=(27xx10^-8xx10000)/(3.14xx10^-8)`
R = 86 Ω
Concept: System of Resistors - Resistors in Series
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