At room temperature what is the strength of the electric field in a 12-gauge copper wire (diameter 2.05 mm that is needed to cause a 2.75 a current to flow?

Electric field strength = resistivity of copper x current density

where

p = 1.72 x 10^-8 ohm meter

diameter = 2.05mm=.00205 m

current = 2.75 A

get first the current density:

current density = current / cross section area

find the cross section area

cross section area = pi. (d/2) ^2;

cross section = 3.3 006x10-6 m^2

substitute the values

current density = 2.75A/3.3006x 10-6m^2

current density=35.55 x1 0^2 A/m^2

Electric field stregnth = 1.72 x 10^-8 ohm meter x 35.55 x10^2 A/m^2

Electric field stregnth = 46.415 Volts/m

The electric field strength of copper is 46.415 V/m.