(a) A copper wire and an iron wire have the same length and same diameter and carry same current I. In which wire is the electric field greater?(b) Can a 1mm in diameter copper wire have the same resistance as a tungsten wire of the same length?[Use p(copper)=1.7x10^-8 ohm meters, p(iron)=1x10^-8 ohm meters, p(tungsten)=5.6x10^-8 ohm meters]
a) for them to carry the same current (with equal lengths and diameters) the iron wire must have a higher voltage between the ends. Iron has higher resistance than copper. Because the iron wire has a higher voltage across an equal distance, it has a greater electric field. b) yes, but the tungsten wire must have a larger diameter than the copper.
a Since copper has higher resistivity than iron, the voltage drop in the copper wire with the same dimensions as the iron wire is greater, meaning more Volts/meter in the copper wire so the E field is greater in the copper wire. b Resistance is proportional to length, resistivity, and inversely proportional to diameter. Increasing the diameter could compensate for a material with higher resistivity. So the answer is yes.
