A long transmission cable must carry a steady current of

PHYSICS · Single correct · CBSE · Physics · Current Electricity · Current Electricity

Problem

A 200 m200\,\text{m} long transmission cable must carry a steady current of 50 A50\,\text{A}. Two cables, each of circular cross-sectional area 5.0×10−6 m25.0 \times 10^{-6}\,\text{m}^2, are being considered. Option I: aluminium, ρ=2.8×10−8 Ωm\rho = 2.8 \times 10^{-8}\,\Omega\text{m} Option II: steel, ρ=1.6×10−7 Ωm\rho = 1.6 \times 10^{-7}\,\Omega\text{m} For the same current, which cable will waste less power as heat, and by approximately what factor compared with the other option? (a) Steel cable; about 66 times less power loss (b) Aluminium cable; about 22 times less power loss (c) Aluminium cable; about 66 times less power loss (d) Steel cable; about 22 times less power loss

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