(a) for a face-centered cubic (fcc) unit cell, determine which plane has the highest atomic density (number of atoms per unit area): (100), (110) or (111).
(b) from your answer to (a) calculate the highest planar atomic density for cu (fcc with a = 3.61 a).
(c) for a body-centered cubic (bcc) unit cell, determine which plane has the highest atomic density (number of atoms per unit area): (100), (110) or (111).
(d) from your answer to (c) calculate the highest planar atomic density for fe (bcc with a = 2.86 a).

Auniform electric field exists in the region between two oppositely charged plane parallel plates separated by a distance of 1.60 cm . a proton is released from rest at the surface of the positively charged plate and strikes the surface of the opposite plate in a time interval of 3.20×10-6 s. 1-find the magnitude of the electric field. use 1.60×10-19c for the magnitude of the charge on an electron and 1.67×10-27kg for the mass of a proton 2-find the speed of the proton when it strikes the negatively charged plate