23P3Q03

3a)

(Net) Rate of flow of electric charges.

3b)

Volume of the conductor\displaystyle =Al

Number of charges in the conductor \displaystyle =n(Al)

Amount of charges in the conductor \displaystyle \Delta Q=n(Al)q

Time taken for these charges to flow out of the conductor\displaystyle \Delta t=l\div v

Current \displaystyle I=\frac{\Delta Q}{\Delta t}=\frac{nAlq}{l\div v}=nAvq

3ci)

\displaystyle \begin{aligned}  I&=nAvq \\ 2.00&=\frac{1.45\times {{10}^{23}}}{A(3.00)}Av(1.60\times {{10}^{-19}}) \\ v&=2.59\times {{10}^{-4}}\text{ m }{{\text{s}}^{-1}} \end{aligned}

3cii)

At any one time, the electrons are travelling at high speed in different directions.

The drift velocity is average velocity of all the electrons in one direction along the wire.

OR

As the electrons move along the wire, they keep changing direction as they collide with the metal lattice again and again.

Even though the total distance travelled is very large (hence high speed), the net displacement is very small (hence low velocity).

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