# Formula: Polarization of a Material Electric field (E field)    Electric susceptibility

## Polarization

Unit
Polarization describes the density of electric dipoles in a material (number per volume) and induces a polarization field $$\class{purple}{E_{\text{p}}}$$, which can be aligned either opposite or in the same direction as the external electric field, thereby amplifying or weakening the external electric field.

## Electric field (E field)

Unit
External electric field in which the dielectric material is situated.

## Electric susceptibility

Unit
Electric susceptibility indicates how well a material can be polarized by an external electric field $$\class{purple}{E}$$. In other words, it quantifies how effectively the external electric field is weakened or strengthened within the material.
• For $$\class{green}{\chi_{\text{e}}} > 0$$, the external electric field is amplified within the material.
• For $$\class{green}{\chi_{\text{e}}} < 0$$, the external electric field is weakened within the material.
• For $$\class{green}{\chi_{\text{e}}} = 0$$, it is neither weakened nor strengthened. The "material" is vacuum.
Material Electric susceptibility
Vacuum 0
Air (0°C) 0.0005
Glass 4 bis 9
Water (0°C) 87
Water (40°C) 72.4
Ice (-20°C) 15
Hydrogen Cyanide 94
Ethanol (20°C) 24.8
Electric susceptibility of some materials

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