
The magnetic flux through the cross-sectional area of the core can be calculated as follows.

In accordance with the Ampere's Law, we can calculate the magnetic flux density in the core at an arbitrary distance r from its central axis. We can find the formula for the inductance of a rectangular cross-section toroidal coil step by step based on fundamental laws of electromagnetism. Inductance calculation of a ferrite toroid coil

Features of calculation of power supply chokes.How to calculate single layer LC-circuit coil in Coil64?.
