# Formula: Electric Susceptibility Relative permittivity

## 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

## Relative permittivity

Unit
Relative permittivity is an alternative quantity to susceptibility that describes how well a material can be polarized.

## The Most Useful Physics Formula Collection on the Internet

+ Perfect for high school and undergraduate physics students
+ Contains over 500 illustrated formulas on just 140 pages
+ Contains tables with examples and measured constants
+ Easy for everyone because without vectors and integrals