As it is known that the polarization of dielectrics takes place in the external electric field. As the magnitude of electric field goes on increasing, the molecules starts spreading. At a certain stage when electric field will be increased to a higher limit, then the breaking of the molecules will start taking place. Due to this breakage of the molecules the dielectric will become a conducting material.
The proper definition of dielectric is: ‘Strength of dielectric means that the maximum magnitude of electric field that it can bear without having any breakage in the molecules.The dielectric strength of some of the materials is given with the values of the dielectric constant .
| Dielectric | Dielectric constant | Dielectric Strength |
| Mica | 6-7 | 80 |
| PVC | 5-6 | 30 |
| Zircon | 7.1-9.1 | ——- |
| Vaccum | 1.000 | ∞ |
| Polythene | 2.3 | 20-160 |
| Natural Rubber | 2.7-5.0 | 18-24 |
| Teflon | 2.1 | 16-20 |
To get freedom from danger, electric field is not applied equal to the strength of the object. The amount of electric field applied is only ten percent of the dielectric strength of the material.
