A copper wire has a square cross section 2.3 mm on a side. The wire is 4.0

Question:

A copper wire has a square cross section 2.3 mm on a side. The wire is 4.0 m long and carries a current of 3.6 A. The density of free electrons is 8.5 X 1028/m3. Find the magnitudes of
(a) The current density in the wire and
(b) The electric field in the wire.
(c) How much time is required for an electron to travel the length of the wire?