Question

Define drift velocity
and derive an expression
for it.​

Answer 1

Answer:

a drift velocity is the average velocity attained by charged particles, such as electrons, in a material due to an electric field. In general, an electron in a conductor will propagate randomly at the Fermi velocity, resulting in an average velocity of zero.

Explanation:

Following is the derivation of drift velocity:

F=−μE a=Fm=−μEm u=v+at

Here,

v = 0

t = T (relaxation time that is the time required by an electron to return to its initial equilibrium value)

u=aT (substituting for v and u)

∴u=(−μEm)T (substituting for a)

Answer 2

Answer:

Drift velocity is defined as the average velocity attained by the particles (electrons) of a given material due to an electric field that is proportional to current. Ohm’s law can be expressed in terms of drift velocity as follows:

u=μE

Where,

u: drift velocity (m/s)

μ: material’s electron mobility (m2/V.s)

E: electric field (V/m)

Derivation of Drift velocity

Following is the derivation of drift velocity:

F=−μE a=Fm=−μEm u=v+at

Here,

v = 0

t = T (relaxation time that is the time required by an electron to return to its initial equilibrium value)

u=aT (substituting for v and u)

∴u=(−μEm)T (substituting for a)

This is the final equation explaining drift velocity.

But as the temperature increases, the drift velocity of electrons increases in a metallic conductor.

This was the derivation of drift velocity. Stay tuned with BYJU’S and learn various other Physics topics.