In physics, the term dielectric strength has the following meanings:
1. Of an insulating material, the maximum electric field strength that it can withstand intrinsically without breaking down, i.e., without experiencing failure of its insulating properties.
The theoretical dielectric strength of a material is an intrinsic property of the bulk material and is not dependent on the configuration of the material or the electrodes with which the field is applied.
2. For a given configuration of dielectric material and electrodes, the minimum electric field that produces breakdown.
At breakdown, the electric field frees bound electrons, turning the material into a conductor.
The field strength at which breakdown occurs in a given case is dependent on the respective geometries of the dielectric (insulator) and the electrodes with which the electric field is applied, as well as the rate of increase at which the electric field is applied.