Question

what is permiability and permittivity? what is the importance of using it in the electro and magnetostatics?

Answer 1

Note that both of these terms have their roots in the word "permit", so it's a question of how much they permit. Think of it like the opposite of "resist" as in "resistance", although technically the opposite to resistance is impedance.
permeability: (According to my science dictionary), the degree to which a solid admits the passage of fluids (there is also magnetic permeability).
permittivity: symbol: epsilon, normally we are talking about electrixc fields here, and the relative permittivity of different materials.The relative permittivity of a material under given conditions reflects the extent to which it concentrates electrostatic lines of flux.

Answer 2

They are both material constants (though constant is a bit of a misnomer since in materials they are usually temperature and frequency dependent). Put simply they are a coefficient of dielectric and magnetic materials which determines the degree of polarisation (for permittivity) magnetisation (for permeability) in response to an applied electric or magnetic field.

They are important in electro and magnetostatics, since they play a role in other applications. For example, a capacitor consisting of a dielectric of permittivity \(\varepsilon\) and thickness \(d\) sandwiched between two electrodes will have a capacitance equal to \[C=\frac{\varepsilon A}{d}\]Since the charge \(Q\) on a capacitor is given by \[Q=CV\] we can see that \[Q=\frac{\varepsilon AV}{d}\]and thus the amount of charge stored on a capacitor is dependent upon the magnitude of the permittivity. Therefore materials with a higher permittivity make better logic devices and volatile memories when integrated into silicon technology (Computer RAM, identity chips etc).

There is a direct analogue for permeability for magnetic materials, but I am less knowledgeable in this aspect.

Answer 3

thank u