# Charge Density Formula

The charge density is the measure of electric charge per unit area of a surface, or per unit volume of a body or field.

The charge density tells us how much charge is stored in a particular field. Charge density can be determined in terms of volume, area, or length.

Depending on the nature of the surface charge density is given as the following

## Linear Charge Density

$\lambda =q/l$

where q is the charge and l is the length over which it is distributed

S.I unit of Linear charge density is coulomb/m

## Surface Charge Density

σ = q / A

where q is the charge and A is the area over which it is distributed

S.I unit of Linear charge density is coulomb/$m^{2}$

## Volume Charge Density

ρ = q / v

where q is the charge and V is the volume over which it is distributed

S.I unit of Linear charge density is coulomb/$m^{3}$

### Solved Example

Find the charge density if a charge of 8 C is present in a cube of 4 m3

Solution

Given :

Charge q = 8 C

Volume v = 4 m3

The charge density formula is given by

ρ = q / v

= 8 / 4

Charge density ρ = 2 C/m3