question_answer 13)

The number density of free electrons in a copper conductor estimated in Example 3.1 is 8.5 x 1028 m–3. How long does an electron take to drift from one end of a wire 3.0 m long to its other end? The area of cross-section of the wire is 2.0 x 10–6 m2 and it is carrying a current of 3.0 A. 

Answer:

Using  we get                                 = 1.1 × 10?4 m s?1                               Time taken,                 = 2.72 × 104s.