Drift Velocity and Current in a Conductor

Drift velocity and thermal velocity are two types of velocities that describe the motion of electrons in a conductor. However, only the drift velocity determines the current in a conductor.

Drift Velocity:

- Drift velocity is the average velocity with which the free electrons move in a conductor due to the presence of an electric field.
- It is a very slow velocity, typically on the order of millimeters per second.
- The drift velocity of electrons is dependent on the electric field strength and the resistivity of the conductor.
- The direction of drift velocity is opposite to the direction of the electric field.

Current in a Conductor:

- Current is defined as the flow of electric charge through a conductor.
- It is measured in amperes (A) and is given by the rate of flow of charge per unit time.
- The direction of current is the direction of flow of positive charge.

Relationship Between Drift Velocity and Current:

- The current in a conductor is directly proportional to the drift velocity of electrons.
- As the drift velocity increases, the current in the conductor also increases.
- However, the drift velocity is very small compared to the thermal velocity, which is the velocity with which electrons move randomly due to thermal energy.
- Hence, the thermal velocity does not contribute significantly to the current in a conductor.

Conclusion:

Thus, we can conclude that only the drift velocity of electrons determines the current in a conductor. The thermal velocity does not contribute significantly to the current.