In: Physics
3.3 L and C with non-vacuum filler
If we fill the space between the plates of a capacitor with an insulator the capacitance changes by a factor k called the dielectric constant due to a change in the electric field. A similar effect is observed if we fill the inner volume of a coil acting as a solenoid (the core of the solenoid), only the inductance changes due to a change in the magnetic field. Let us assume when we fill the core with some matter. The inductance will change from L to L
LC circuit in series: and
and the resonance can be found as:
We can review an example for it: the absolute permeability of a soft iron core is given as 80 milli-henries/m. And we can compute the equivalent relative permeability value:
And as we can see when ferromagnetic materials are used in the core the use of relative permeability to define the field strength gives a better idea of the strength of the magnetic field for the different types of materials used.
A better example to understand is: vacuum and air, both they have a relative permeability of one and for an iron core it is around 500, so we can say that the field strength of an iron core is 500 times stronger than an equivalent hollow air coil.