Answer / sagar hingmire

Dielctric medium means a medium which is partially a
conductor & partially a insulator.
Take example of Air as dielectric medium,up to 30 kV air is
a good insulator but beyond 30 kV air acts as a
conductor.That means dielectric value or Breakdown voltage
(BDV) of air is 30 kV.
For water as we know water is very good conductor of
electricity,Heat so water is not a dielectric but it is a
conductor.

Answer / sidharth

Dielectrics are insulators. Only when the applied field across the medium is very high i.e. greater than the breakdown voltage of the dielectric, the dielectric breaks down, thus losing its prime property. SO, i think it cannot be called a 'partial conductor' since it is forced to conduct, not naturally.
Dielectric strength of dry air is 30kV/cm
" " " moist air is 10kV/cm
Water is a pure conductor.

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