Question

Write the definition of drift velocity

Answer 1

Drift Velocity ($v_d$)
When a potential difference (V) is applied across the conductor of length (I), then an electric field ($\overrightarrow{E}$) develops in the conductor ($E=\frac{V}{l}$) Due to this field each free electron of the conductor experiences an electric force $\overrightarrow{F}=-e\overrightarrow{E}$ towards the positive end of the conductor and hence it starts accelerated motion $(\overrightarrow{a}=\frac{\overrightarrow{F}}{m}$) m towards the positive end. During its accelerated motion it collides with the other electrons and positive ions of the conductor. Therefore its velocity always remains changing. This motion of electron is known as 'Drift motion' and the average velocity between two successive collisions is known as 'Drift velocity.' It is denoted by $v_d$.