What is the length of copper wire is required to produce a 4mohm resistor? Assume the diameter of the wire is 1mm and that the resistivity roh copper is .0000000178ohmm

Answer 1

R = pL/A.

A = pi*r^2 = 3.14*(1/2)^2 = 0.7854 mm^2

4 = 1.78*10^-4*L/0.7854.
4 = 2.2664*10^-4L,
L = 1.765*10^4 mm = 17.65 m.