Question

If the dielectric constant and dielectric strength be denoted by $K$ and $X$ respectively, then a material, suitable for use as a dielectric in a capacitors, must have :

• A. high $K$ and high $X$
• B. high $K$ and low $X$
• C. low $K$ and high $X$
• D. low $K$ and low $X$

Answer 1

The correct option is A high $K$ and high $X$

The dielectric strength is the maximum electric field that a pure material can withstand under ideal conditions without breaking down. For high voltage capacitors we use practically high dielectric strength.
If a material with a high dielectric constant is placed in an electric field, the magnitude of that field will be measurably reduced within the volume of the dielectric. This fact is commonly used to increase the capacitance of a particular capacitor design.
So for good capacitors we require high K and high X.