# Describing sources

## Introduction

We distinguish two types of sources:

• an imposed electric charge density (q0)
• an imposed electric potential (V0)

The describing of these two types of sources in Flux software is detailed in the following blocks.

## Imposed electric charge density

It is possible to impose a density of electric charge (q0) on a region by:

• using the material regions of dielectric type (as presented previously): the volume density of electric charge of sources is then one of the data entered during the definition of the dielectric region
• using the regions known as non-material of the type:

imposed density of electric charge

## Expression of the electric charge density

The electric charge density of sources represents the q term in the solved equation of electrostatic applications (see § Electro Static: solved equations).

The expression of this density depends on the used type of region. Information by the region type is gathered in the table below.

For a region… the density of the charges is a…
material

massive thin (withthickness) filiform (with cross-section)

volume density (or the total electric charge)

uniform or space dependent
non-material face (3D) surface density
line line density

## Imposed electric potential

It is possible to impose an electric potential (V0) on a region by:

• using the material regions of perfect conductor type (as presented previously): the electric potential is then one of the data entered during the definition of the region
• using the regions known as non-material of the type: imposed electric potential

## Expression of the electric potential

The expression of the electric potential depends on the used type of region.

Information by the region type is gathered in the table below.

For a region… the electric potential is…
perfect conductor uniform
imposed potential uniform or space dependent