1)suppose we start with an electron with zero initial velocity.Let Ï be
the typical time it would take for ourelectron to hit an atom. We can use this as
an average time between collisions as theelectron makes its way through the
material. What is the typical velocityof the electron when it hits an atom?
2) It turns out that the velocity you justcalculated is not a bad estimate of the drift
velocity, vd. Now, as we saw, there isanother way to write vd, namely
J = (âne)vd for electrons(remember J = i / A for uniform currentdensity), where
n is the number of charge carriers(electrons) per unit volume. Solve this for |vd|
and equate with what you got in (1).
3)In the above, you should have a J on oneside and an E on the other. Now J and E
are in another important equation from today. Given that, can youfind an
expression for the resistivity of the material, ??
4)Also, we just saw in lecture that R =(L/A)?, where L is the length of the wire and
A is its cross-sectional area. So, what
