Question

What is the difference b/w drift velocity and random motion of electrons. how electron change their velocities when electric field is applied?

Answer 1

DIFFERENCE BETWEEN DRIFT VELOCITY AND RANDOM MOTION OF ELECTRON
The drift velocity is the averagevelocity that a particle, such as anelectron, attains in a material due to an electric field. In general, an electronwill propagate randomly in a conductor at the Fermi velocity. An applied electric field will give this random motion a small net flow velocity in one direction.
HOW ELECTRON CHANGE THEIR VELOCITY
The definition of drift velocity can be understood by imagining the random motion of free electrons in a conductor. The free electrons move in a conductor with random velocities and random directions. When we apply an electric field across the conductor, the randomly moving electrons experience an electrical force in the direction of the field.Due to this field, the electrons do not give up their randomness of motion, but they will shift towards higher potential with their random motion. That means the electrons will drift towards higher potential along with their random motions. Thus, every electron will have a net velocity towards the higher potential end of the conductor, and we refer this net velocity as the drift velocity of electrons. Hopping, you understand the definition of drift velocity. The current due to this drift movement of electrons inside an electrically stressed conductor, is known as drift current. It is needless to say that every electric current is "drift current"