One dielectric material that I use a lot is paraffin wax which can be found in art stores and is normally used for making candles. Another is resin, the easiest to find being automotive resin used for automotive body repairs.

The positive charges within the dielectric are displaced minutely in the direction of the electric field, and the negative charges are displaced minutely in the direction opposite to the electric field. This slight separation of charge, or polarization, reduces the electric field within the dielectric.

The higher the dielectric constant, the better a material functions as an insulator—for example, rubber has a very high dielectric constant, and so it is often used a protective coating around high voltage wires because its high k makes it a very poor conductor.

The value of the dielectric constant at room temperature (25 °C, or 77 °F) is 1.00059 for air, 2.25 for paraffin, 78.2 for water, and about 2,000 for barium titanate (BaTiO3) when the electric field is applied perpendicularly to the principal axis of the crystal.

The dielectric constant as determined by the method below is: 2.2. 2.2 is the capacitance of the wax capacitor (0.053 nF) divided by the capacitance of the air capacitor (0.024 nF).

Some common materials and their relative permittivity

Dielectric strength is an intrinsic material property that represents the maximum electric field a pure material is able to sustain ideally before its insulating properties begin to fail. It can also be described as the highest voltage needed to induce a dielectric breakdown [1].