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## Homework Statement

Copper and aluminum are being considered for a high‐voltage transmission line that must carry a current of 51.4 A. The resistance per unit length is to be 0.176 Ω/km. Compute the magnitude of the current density for an aluminum cable.

## Homework Equations

[itex]R\quad =\quad \frac { \rho L }{ A } \\ J\quad =\quad \frac { I }{ A } [/itex]

## The Attempt at a Solution

[itex]\frac { R }{ L } \quad =\quad 0.176\frac { \Omega }{ km } \quad =\quad 1.76x10-4\frac { \Omega }{ m } \\ \\ \frac { R }{ L } \quad =\quad \frac { \rho }{ A } \quad \quad \quad \quad \quad A\quad =\quad \frac { I }{ J } \\ \\ \frac { R }{ L } \quad =\quad \frac { \rho J }{ I } \\ \\ \frac { RI }{ L\rho } \quad =\quad J\quad =\quad 1.76x10-4\quad *\quad \frac { 51.4 }{ 2.65x10-8 } \quad =\quad 3.41x10+5\quad [/itex]

This is marked as wrong, any tips?