What is the Drift Velocity of free electrons in a conductor?
1 Answer
The drift velocity of free electrons in a conductor refers to the average velocity at which these electrons move in response to an electric field. In a metallic conductor, such as a wire, there are numerous free electrons that are not bound to individual atoms and are relatively free to move throughout the material.
When an electric potential difference (voltage) is applied across the conductor, an electric field is established within it. This electric field exerts a force on the free electrons, causing them to move in the direction of the electric field. However, they don't move with very high speeds like in a gas or a vacuum due to collisions with atoms and other electrons in the conductor.
The drift velocity, denoted by
v
d
, is the average velocity of these electrons as they move in response to the electric field. It's important to note that the drift velocity is generally quite small compared to the actual speeds of electrons. The formula for drift velocity is given by:
=
v
d
=
nAe
I
Where:
v
d
is the drift velocity of electrons (m/s).
I is the electric current flowing through the conductor (Amps).
n is the number of charge carriers (free electrons) per unit volume of the conductor (1/m³).
A is the cross-sectional area of the conductor (m²).
e is the elementary charge (approximately
1.602
×
1
0
−
19
1.602×10
−19
Coulombs).
As you can see from the formula, the drift velocity is directly proportional to the current and inversely proportional to the number of charge carriers and the cross-sectional area of the conductor. Since the drift velocity is typically quite small due to the high density of charge carriers in a conductor and the frequent collisions they experience, the actual electron speeds remain much higher but with random motion.
It's also worth noting that the drift velocity concept is a simplified model used to describe current flow in conductors. In reality, electrons move in a more complex and erratic manner due to collisions and interactions with the conductor's atomic lattice.
When an electric potential difference (voltage) is applied across the conductor, an electric field is established within it. This electric field exerts a force on the free electrons, causing them to move in the direction of the electric field. However, they don't move with very high speeds like in a gas or a vacuum due to collisions with atoms and other electrons in the conductor.
The drift velocity, denoted by
v
d
, is the average velocity of these electrons as they move in response to the electric field. It's important to note that the drift velocity is generally quite small compared to the actual speeds of electrons. The formula for drift velocity is given by:
=
v
d
=
nAe
I
Where:
v
d
is the drift velocity of electrons (m/s).
I is the electric current flowing through the conductor (Amps).
n is the number of charge carriers (free electrons) per unit volume of the conductor (1/m³).
A is the cross-sectional area of the conductor (m²).
e is the elementary charge (approximately
1.602
×
1
0
−
19
1.602×10
−19
Coulombs).
As you can see from the formula, the drift velocity is directly proportional to the current and inversely proportional to the number of charge carriers and the cross-sectional area of the conductor. Since the drift velocity is typically quite small due to the high density of charge carriers in a conductor and the frequent collisions they experience, the actual electron speeds remain much higher but with random motion.
It's also worth noting that the drift velocity concept is a simplified model used to describe current flow in conductors. In reality, electrons move in a more complex and erratic manner due to collisions and interactions with the conductor's atomic lattice.