Capacitance - Dielectric Strength

Dielectric strength is the measure of a dielectric's ability to resist electric stress without losing its insulating capabilities. A high dielectric constant does not always correspond to high dielectric strength. Distilled water has a fairly high dielectric constant but it has poor dielectric strength. Water, therefore, is not a useful dielectric for capacitors because it breaks down too easily. Some ceramics have dielectric constants as high as 10,000. These materials would be extremely valuable if they had better dielectric strength.