2. What is the resistance at normal room temperature of 80 m of copper wire having a diameter of 0.64 mm? (Pcopper = 1.7241 x 10-8 Q- m at 20 °C).

An 18-gauge copper wire with a diameter of 1-mm carries a constant current of 1-A. The charge concentration in the wire is 8.5 x 1028 per cubic meter. Determine the resistance, in ohms, of a 77-m wire in milli-ohm. Use resistivity equal to 1.72x10-8 ohm-m.

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aY A copper wire with (32.3 m) Long, area (5 mm?) and Fhe cross-sectional the resistance is (120 r) at Zero tempera ture Co č) . When the temperature to (50 c) the resistance become rise (144 72), Determine the temperature cofficient (a) the specific resis tivity at (0 C) P.)