A copper wire has a radius of 1 mm and carries current 1 A. What is the drift velocity of electrons? Copper has one free electron per atom. The atomic mass of copper is 63.5 times the mass of a proton. The copper density is 8.94 g/cm³. A. 0.074 mm/s B. 0.037 mm/s C. 0.024 mm/s D. 0.012 mm/s E. 0.061 mm/s