Current Through Metallic Conductor

Current Through Metallic Conductor;

The valance electrons in metals are not bound to the individual atoms but are free to move in metals. These electrons are called free electrons. The speed of randomly moving depend upon temperature. 

Motion Of Free electron metals:

The free electrons in metals are in random motion just like the molecules of the gas in the cantainer.

Current Through Metals When No Battery is Connected:

In this case.the rate at which free electrons pass throngh in from right to left in the same as the rate at which they pass from left to right.As a result,the current throngh the wire is zero.

Current Through Metals When Battery is Connected:

When the end of wire are connected to a battery,an electrons field is set up at every point within the wire.A force acts on the free electrons in a direction opposite to that electric field E.due to the applied field,the electron change their random motion in such a way that they drift slowly with a constant velocity in a direction opposite to the field. The velocity is called drift velocity.Hence,a current begins to flow through the conducter.

Drift Velocity:

The average constant speed with which free electrons drift (flow) when current flows through the conductor is called drift velocity.The drift velocity is of the order of 10m/sec or 1mm/ sec.

Acceleration Of Electrons:

The force experienced by the free electrons does not produce a net acceleration because the electrons keep on colliding with the atoms of the conducter. The overall effort of colliding is to transfer the energy of accelerating electrons to the lattice atoms.

Steady current is maintained is the wire when a constant potential difference is applied across it. It produces the necessary field e along the wire

Note:

The velocity of electrons at room temperature due to thermal motion is several hundred kilometers per second.