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 × 105.
E) +5.43 × 105.