Table of Contents
What is the relation between relaxation time and drift velocity?
The drift velocity is just the average velocity of the charge carriers in the conductor. So, as you now see, the drift velocity is proportional to the relaxation time . As the relaxation time increases the drift velocity increases, because the charge carriers have more time to accelerate between collisions.
What is the relation between current and drift velocity of a conductor with applied voltage?
v=aτ where v is the drift velocity, a is the acceleration and τ is the average relaxation time between two successive collisions. N=nV where N is the total number of electrons, n is the number density of electrons and V is the volume. This is the required relation between the current and the drift speed.
Why do electrons acquire drift velocity?
Electron gains kinetic energy. During movement, electrons collide with other accelerated electron and atom, so they loss kinetic energy. Hence, they cannot accelerate continuously, so they move with steady average drift velocity.
What is dimensional formula of relaxation time?
| Quantity | Dimension | Root definition and Notes |
|---|---|---|
| Relaxation rate | s-1 | 1/[Relaxation time] |
| Frequency of waves | s-1 | hertz |
| Phase drift rate | s-1 | [Phase angle]/[Time] |
| Angular velocity / speed | s-1 | [Plane angle]/[Time] |
What is the formula of relaxation time?
Relaxation time is defined as the time interval between two successive collisions of electrons in a conductor when current flows through it. It is denoted by τ. Consider a conductor having length l, area of cross section A and current density n. Therefore, the expression for electrical resistivity is given by ρ=mne2τ.
Why is drift velocity opposite to electric field?
Drift Velocity The electron paths thus appear nearly random, like the motion of atoms in a gas. However, there is an electric field in the conductor that causes the electrons to drift in the direction shown (opposite to the field, since they are negative).
How to calculate the drift velocity of electrons in a conductor?
Formula for calculating drift velocity of electron in a conductor of constant cross-sectional area is given by V = 1/ nAq Where, ‘v’ is the drift velocity of the electrons ‘I’ is the current flowing through the conductor (amperes)
What is the meaning of a=n in drift velocity?
A = represents the area of the cross-section of the conductor measured in m2. n = represent the number of electrons. As expressed in the formula above for the drift velocity, if out of the four quantities any three quantities are known, then the missing quantity can be found easily.
What is meant by drift current?
Since the electrons are said to be moving with drift velocity, even the current which results due to this drift movement of electrons in an electrically charged conductor is called as the drift current. In fact, every current flowing through the conductor is termed as the drift current.
How does cross sectional area affect drdrift velocity?
Drift velocity does not depend on the cross-sectional area or the diameter of any conductor. For the same p.d. Here, with V across the conductor, an increase in the cross-sectional area decreases the resistance R= (rho) (length)/ (cross-sectional area)