Formula: Electric Susceptibility Relative permittivity
$$ \class{green}{\chi_{\text e}} ~=~ \varepsilon_{\text r} ~-~ 1$$
$$ \class{green}{\chi_{\text e}} ~=~ \varepsilon_{\text r} ~-~ 1$$
$$\varepsilon_{\text r} ~=~ \class{green}{\chi_{\text e}} ~+~ 1$$
Electric susceptibility
$$ \class{green}{\chi_{\text e}} $$ 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 |
Relative permittivity
$$ \varepsilon_{\text r} $$ Unit $$ - $$
Relative permittivity is an alternative quantity to susceptibility that describes how well a material can be polarized.