1. A 260 ft (79.25 m) length of size 4 AWG uncoated copper wire operating at a tem-
perature of 75°C has a resistance of approximately:
A. 0.0801 ohm.
C. 0.308 ohm.
E. 1.010 ohm.
B. 0.0792 ohm.
D. 0.524 ohm.

A 260 ft (79.25m) length of size 4 AWG uncoated copper wire operating at a temperature of 75°c has a resistance of 0.0792 ohm.

Explanation:

From the given data the area of size 4 AWG of the code is 21.2 mm², then K is the Resistivity of the material at 75°c is taken as ( 0.0214 ohm mm²/m ).

To find the resistance of 260 ft (79.25 m) of size 4 AWG,

R= K * L/ A

K = 0.0214 ohm mm²/m

L = 79.25 m

A = 21.2 mm²

R = 0.0214 *

  = 0.0214 * 3.738

  = 0.0792 ohm.

Thus the resistance of uncoated copper wire is 0.0792 ohm

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