Question

1-how each dielectric material has its own unique specific dielectric constant. The textbook and other resources refer to the constant as "k" but wouldn't each material having its own constant ruin the purpose of a "constant" being the same value for every dielectric material?

2-What the dielectric does exactly?

3-why we only consider one of two similar junctions in a circuit. Why do we not consider the other junction if they are equivalent equations?

Answer 1

Part 1:

The relative permittivity (k) is a measure of how easily a material is polarized when there is an external electric field on an insulator.

Remember that:

K is constant for the dielectric

Part 2:

A dielectric is used to increase the breaking potential for a capacitor. If you have a capacitor plate separated by air, there is a capacitance. When you use a dielectric, this capacitor will stored larger amount of charge.

Part 3:

Two junctions are similar, because the current the flow in is the same the current flows out.