The Diameter of No

Multiple Choice

The diameter of no. 12 copper wire is 0.081 in. The maximum safe current it can carry (in order to prevent fire danger in building construction) is 20 A. At this current, what is the drift velocity of the electrons? (The number of electron carriers in one cubic centimeter of copper is 8.5 × 10²².)

A) 0.044 mm/s
B) 0.44 mm/s
C) 0.44 cm/s
D) 0.44 m/s
E) 4.4 m/s