*Effective mass *

An electron in a
crystal interacts with the lattice potential, hence its response to external
force is different from a free electron. Hence the deviation of electrons
behavior is taken into account by considering electrons to have effective mass.

It can be negative and
positive or infinite. It is given by

According to de-Broglie
theory, the velocity of an electron with wave vector K is the same as group velocity of
wave representing the electron i.e.

Whereis the angular frequency and is related to the
electron energy E by the relation.
In term of energy, the velocity is expressed as

Therefore by using eq. (2) in eq. (1), we get

Now

Hence to get
acceleration, differentiating this eq. w.r.t

From eq. (3) and (4), we get

Comparing this result
with classical result

In fig.is represented as a function of

## 1 Comments

u have explained each and every point...thankyou

ReplyDeleteIf you have any doubt, please let me know