Self-inductance of a toroid with a rectangular cross section

[Ravasash]

I have found answers on how to calculate the self-inductance of toroid of rectangular cross section, however my question says that "The winding are seen as a thin homogeneous currentlayer around the core" (excuse the translation). What does that mean for N? Does it mean N=1?

 

[Hesch]

Does it mean N=1?

Yes.
Say that the original values are: N = N_org , I = I_org.
In the approximated model the values become:
N_app = 1 , I_app = I_org * N_org.
The reason for this approximation is that the coil is formed like the thread on a screw, which make calculations difficult.