Electronic Devices - Semiconductors - Discussion

The free electrons in a conductor are already in motion due to thermal agitation. This is called random motion of electrons and it does not produce any current in the conductor as the average charge crossing any section of the conductor is zero.

However, when a potential difference is applied across the conductor, an electric field is set up inside the conductor which accelerates all the free electrons in a direction opposite to the field direction.

This produces a drift velocity for the free electrons which is superimposed on the thermal velocity. The drift of free electrons causes current flow through conductors.

The direction of conventional current is opposite to the direction of drift of free electrons.

In conductor without giving any external power supply, electrons moves randomly but in question it's not given. So how current is possible inside the conductor?

Without giving any source in conductor, I=0.
How answer B is correct, Please explain it.

According to energy band theory the band of energy level which are for away from the nucleus is conduction band so this electrons does not affect strongly by nucleus so it can move as freely with in conduction band. It cause electron current.

But I think he is asking about free electrons. But when current flows in a conductor, electrons flows in a specific direction opposite to that of current direction.

Therefore we can't say electrons are free.

Hello @Binod.

In the question movement of free e-(the movement itself saying that source already given to the device or condition what ever).

Yeah, you both correct.
Current is due to flow of free electrons.
Current direction is always opposite to flow of electrons direction.

Current flows opposite to the direction of electron. But definitely its our assumption current is because of electron only.

By flow of electrons it leads to the electrical conduction. The movement of flow of electrons is known as current.

How is it possible, without giving any external power supply to the conductor I=0.

Yeah it is obvious that flow of electrons lead to current.