Question

How long does it take electrons to get from a car battery to the starting motor? Assume the current is i and that the electrons travel through a copper wire with cross-sectional area Aand length L. The number of charge carriers per unit volume is n. State your answer in terms of the given variables, using e for the elementary charge.

Answer 1

`t=(L(nA))/(I)`

Step-by-step explanation:

The concentration of electron/volume is n

A is the cross-sectional Area

I the current

L the lenght

So,

The drift velocity of the electron is given by the equation,

`v = (I)/(n A)` (1)

The time required is given by,

`t = ( L)/( v)`

So putting (1) in (2) we have,

`t=(L(nA))/(I)`