The density of free electrons in gold is 5.90 × 1028 m−3. A gold wire of length 30 cm and cross-sectional area 1.0 × 10−6 m2 carries a current of 1.18 A. The drift speed of electrons in the wire is close to
1
0.125 mm/s
2
2.4 mm/s
3
6.2 mm/s
4
1.3 cm/s