# Define the term ‘mobility’ of charge carriers. Write its S.I. unit.

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Updated on: September 25th, 2023

The drift velocity of the charge carrier per unit of the electric field is used to determine charge carrier mobility. Mobility = drift velocity/ electric field It is denoted by μ and is given as μ = vd/E. Electrons and other subatomic particles constantly migrate in arbitrary ways. When exposed to an electric field, electrons do travel randomly, but they do so slowly in the direction of the applied electric field.

### SI unit of Mobility

To determine drift velocity, we can apply the formula shown below:

I = nAvQ

Where, n is the number of electrons

I is the current flowing through the conductor which is measured in amperes

v is the drift velocity of the electrons

A is the area of the cross-section of the conductor which is measured in m2

Q is the charge of an electron which is measured in Coulombs

SI unit of mobility:

Since,

Mobility μ = drift velocity(vd)/ electric field(E)

SI unit of mobility = SI unit of drift velocity/ SI unit of electric field

SI unit of mobility = ms-1/ Vm-1

SI unit of mobility = m2 V-1 s-1

Summary:

## Define the term ‘mobility’ of charge carriers. Write its S.I. unit.

The drift velocity of the charge carrier per unit of the electric field is the mobility. m2 V-1 s-1 is the SI unit of mobility. The drift velocity refers to the overall speed of these electrons.

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