A copper wire has a circular cross section with a radius of 2.31 mm. HINT (a) If the wire carries a current of 3.78 A, find the drift speed (in m/s) of electrons in the wire. (Take the density of mobile charge carriers in copper n = 1.10 x 1029 electrons/m.) x m/s (b) For the same wire size and current, find the drift speed (in m/s) of electrons if the wire is made of aluminum with n = 2.11 x 1029 electrons/m m/s