Question

Derive the Expression for Drift Velocity​

Answer 1

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HERE IS THE ANSWER FOR YOU

DRIFT VELOCITY

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

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)

HOPE IT HELPS

Answer 2

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i) ❇

When conductor is subjected to an electric field E, each electron experience a force.

F=-eE

and acquires an acceleration

a = F/m = - eE/m -----(i)

Here m = mass of election, e = charge, E = electric field.

The average time difference between two consecutive collisions is known as relaxation time of election.

(ii)❇

According to drift velocity expression, relaxation time is the time interval between successive collisions of an electron on increasing temperature, the electrons move faster and more collisions occur quickly. Hence, relaxation time decreases with increase in temperature which implies that drift velocity also decreases with temperature.

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