A coil is a wire, usually copper, wound, usually in a spiral, with or without a core.
This core can be air or a ferromagnetic material. When a core of ferromagnetic material is present, its inductance increases.
Compute a coil for a given inductance, works well on low inductance coils with an air core, require to know the Absolute Magnetic Permiability for other cores.
There is a reference table of Absolute Magnetic Permiability for various materials at the end of page.
Fill the three requeired values, the number of turns of wire, the diammeter of coil and the length.
*GEMENI NOTE:"There is no exact diameter beyond which the formula becomes invalid. The accuracy of the formula gradually decreases as the coil diameter increases or decreases, or as the coil shape departs from a perfect cylinder."
| N | Number of turns |
| u | Absolute Magnetic permiability henry/m |
| l | Lenth of coil in mm |
| A | Coil Area in mm |
| L | Coil inductance in henry |
| N | |
| d | |
| l | |
| u | |
| A | |
| L | |
| ---| Cientific Notation |--- | ||||
| femto | pico | nano | micro | mili |
| e-15 | e-12 | e-9 | e-6 | e-3 |
| Kilo | Mega | Giga | Tera | Peta |
| e+3 | e+6 | e+9 | e+12 | e+15 |
Absolute Magnetic permiability
| Material | Min. | Max. | Med. |
| Air | --- | --- | 1.257e-6 |
| Iron (99.95% pure Fe annealed in H) | --- | --- | 2.500e-1 |
| Iron (99.8% pure) | --- | --- | 6.300e-3 |
| Ferrite (cobalt nickel zinc) | 5.030e-5 | 1.570e-4 | 1.037e-4 |
| Ferritic stainless steel (annealed) | 1.260e-3 | 2.260e-3 | 1.760e-3 |
| Ferrite (nickel zinc) | 1.260e-5 | 2.890e-3 | 1.451e-3 |
| Ferrite (manganese zinc) | 4.400e-4 | 2.510e-2 | 1.277e-2 |
| Ferrite (magnesium manganese zinc) | 4.400e-4 | 6.280e-4 | 5.340e-4 |
References:
Electronics-Tutorials Permeability_(electromagnetism)