Electronic – the difference between flux and flux-linkage? how to calculate inductance of transmission lines

fluxmains

in calculating inductance of a single current carrying conductor how flux linkage is calculated?why flux is multiplied by a factor (X^2)/(r^2) to get flux linkage.
see the following images:

see the red marked line

Best Answer

dPhi is written as the flux through a cylindrical shell (dx) for a current I.

However, in this case, flux linkage is only part of the total flux derived from I, that is, the flux that derives from the part of the current that goes through a radial section of radius x < r.