Question

The number density of free electrons in copper is 8.5 *10^28 . What is the time taken

Answer 1

Number density of free electrons in a copper conductor, n = 8.5 × 1028 m - 3 Length of the copper wire, l = 3.0 m

Area of cross-section of the wire, A = 2.0 × 10 - 6 m2

Current carried by the wire, I = 3.0 A, which is given by the relation,

I = nAeVd

Where,

e = Electric charge = 1.6 × 10 - 19 C

Vd = Drift velocity

Therefore, the time taken by an electron to drift from one end of the wire to the other is 2.7 × 104 s.