Explain the term ‘drift velocity’ of electrons in a conductor. Hence obtain the expression for the current through a conductor in terms of ‘drift velocity’.
The velocity gained by the accelerating electrons in uniform electric field inside the conductor is drift velocity. The average velocity, acquired by free electrons along the length of a metallic conductor, due to existing electric field is called drift velocity.
Let ‘n’ be the number density of free electrons in a conductor of length ‘l’ and area of cross-section ‘A’.
Total charge in the conductor, Q = Ne
= (nAl)e
Time taken, t is given by, 
Therefore, the current flowing across the conductor is given by, 
That is, 
, which is the amount of current flowing through a conductor in terms of drift velocity.
