SSE JE Electrical Engineering 29 Oct 2020 Shift 2 Papers

Question : 166 of 200

Marks: +1, -0

Find the resistance of a 1 km strip of copper with rectangular cross section 2.5 cm by 0.05 cm, if

\ρ = 1.75 × 10^{-8} \Ω\m

Solution:

\ρ = 1.75 × 10^{-8} \Ω\m

\l = 1 \km = 1000 \m

\A = 2.5 × 0.05 \cm^2

= 0.125 × 10^{-4} \m^2

\R ={1.75 ×10^{-8} ×1000}/{0.125 ×10^{-4}}=1.4 \Ω

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