Drift Velocity, Drift Current and Electron Mobility

The negatively charged particles of an atom, which are called electrons, move. This leads to the generation of electric current and electric fields. Moving electrons create magnetic fields as well. The velocity gained by charged particles, such as electrons in an electric field, is known as the drift velocity. The movement of electrons resulting from the applied electric field is the drift current. Electron mobility is the characteristic of an electron that states how quickly an electron can move through a semiconductor when attracted by an electric field. All of these properties apply to electrons in a conductor.

Drift Velocity

Imagine the random mobility of any free electron in a conductor to understand the definition of drift velocity. Free electrons flow at random speeds and in random directions in a conductor. If an electric field is applied to a conductor, then randomly travelling electrons are subjected to an electrical force towards the field’s direction.

The electrons do not give up their unpredictability of motion due to this field. However, they do shift towards a higher potential due to their random mobility. As a result of their random movements, the electrons will drift in the direction of greater potential. Thus, each electron will have the net velocity towards the higher potential of the wire’s end, which we call the electron drift velocity.

Electrons are driven towards positive potential more quickly after each interaction when the electric field intensity is raised. As a result, the electrons’ average drift velocity increases in the direction of positive potential i.e. in the opposite direction of the applied electric field. The drift velocity is directly proportional to the electric field for electrons in a conductor.

Formula of Drift Velocity

The formula to calculate the drift velocity is given below.

I = nAvQ

I is the amperes, the measured current passing through the conductor.

The letter n denotes the number of electrons.

The area of the conductor’s cross-section, measured in m², is A and the electrons’ drift velocity is v.

The charge of an electron, measured in Coulombs, is known as Q.

Drift Current

The electrons in a semiconductor constantly want to proceed straight towards the battery’s positive terminal. However, they shift the direction of flow due to the constant collisions with atoms. When an electron collides with an atom, it bounces in an unspecified path. The applied voltage does not prevent electrons from colliding and moving randomly, but it does cause them to drift towards the positive terminal.

Drift velocity is the average velocity obtained by an electron or hole due to the applied voltage or electric field. The drift current density is due to free electrons.

The electric current caused by the applied electric field, which is frequently expressed as the electromotive force applied for a certain distance, is known as drift current.

The electric current created by particles dragged by the electric field is known as drift current. The word is most typically associated with electrons in semiconductors, but the concept can be applied to metals and other materials.

The electric force causes drift current: charged particles are propelled by an electric field. 

Negatively charged electrons are forced in the direction opposite to the electric field. In contrast, positively charged holes are forced in the same direction. However, in both circumstances, the resulting conventional current will point in the same direction as the electric field.

When an electric field is supplied to an electron in a vacuum, it accelerates in an almost linear path. The drift stream appears to be very different up close. Electrons often move in all directions at random. They change direction repeatedly when clashing with other disturbances.

The electric field will gently accelerate them in a single way between impacts. So, on average, they move with the drift velocity, while the electrons will move at the (usually a lot faster) thermal velocity at any one time. The total drift current is determined by charge carrier concentration and mobility through the medium.

Electron Mobility

If an electric field is generated into a metal or semiconductor, electron mobility will describe how fast an electron will move through it. For holes, there is a corresponding quantity known as hole mobility. Both hole and electron mobility are referred to as carrier mobility.

Hole and electron mobility indicate the electrical mobility of the charged particles placed in fluid while an electric field is being applied.

Ivan’s electric field is applied over a part of the material, and the electrons act by migrating at a drift velocity.

Conclusion

The electrons in a conductor exhibit various properties while moving through the conductor, like drift velocity, drift current and electron mobility. Drift velocity is the velocity achieved by charged particles, such as electrons in an electric field. Drift current is the movement of electrons due to an applied electric field. Electron mobility is a property of electrons that describes how fast an electron will move through a semiconductor when attracted by an electric field. The drift velocity of an electric wire containing a lot of free electrons is significantly lower than the average.