Question

Define mobility of electrons.

Answer 1

Hint: We know that electron mobility is a type of measurement of how fast an electron can move in the presence of an external electric field. Then we have to write the formula derived for calculating the electro mobility. After that provide the SI unit used for defining mobility mathematically and then write its dimensional form.
Formulas used:
$\mu =\dfrac{{{V}_{d}}}{E}$
$[{{M}^{-1}}{{T}^{2}}A]$

Complete step by step answer:
The measurement of how fast an electron can move through a semiconductor or a metal which is under the influence of an external electric field is known as electron mobility.

We can show electron mobility mathematically by the equation,
$\mu =\dfrac{{{V}_{d}}}{E}$ .
The SI unit of electron mobility under the influence of an external electric field is shown as, ${{m}^{2}}{{V}^{-1}}{{s}^{-1}}$ .
When its SI unit is calculated dimensionally we see that $[{{M}^{-1}}{{T}^{2}}A]$ , is its dimensional form.

Additional Information:
We know that electrons or subatomic particles like electrons tend to move in all directions randomly at all times. But when they are in the presence of an electric field the particles or electrons do move in a random direction but they slowly tend to drift in one side or one direction, that is generally in the direction of the electric field that is applied. This net velocity of the electrons or subatomic particles is known as drift velocity.


Note:
In the formula for electron mobility under the presence of an external electric field, $\mu =\dfrac{{{V}_{d}}}{E}$, $\mu $ denotes the electron mobility, ${{V}_{d}}$ is the drift velocity of the electron and E is the external energy provided by the electric field. In its dimensional form $[{{M}^{-1}}{{T}^{2}}A]$, M denotes the mass, T denotes the time and A denotes electric current.