Here o is the conductivity of the material. (see Table 5-1 for various common materials Microscopically speaking, current in conductor forms due to the drift of conduction electrons = nev ere n-- the conduction electron density, the magnitude of the electron charge he drift velocity of the electron charge For example, in copper, n=8.5 102elctron/M3 if =100 A/M2, then the drift velocity 74×10-5M/s~026M/h 已 -the drift velocity is low different from thermal motion( 10-M/s