The Electron Density in Copper Is 8

Multiple Choice

The electron density in copper is 8.49 *10²⁸ electrons/m³.The electron charge is e = -1.60 *10 ^{- 19} C.When a 1.00 A current is present in a copper wire with a 0.40 cm² cross-section,the electron drift velocity,in m/s,with direction defined relative to the current density,is

A) -1.84 *10 ^{- 6}.
B) +1.84 * 10 ^{- 6}.
C) -1.84.
D) -5.43 * 10 ^- .
E) +5.43 * 10 ^- .