# Self inductance of a circular coil

I have read from my reference that the self inductance of a wire ring is derived in a non-trivial manner. I have copied an image off the result below, let me know if I should translate it to Latex.

My question is one regarding units. It seems the author goes straight from $$\frac{s^2}{cm} to$$ $$H$$. How can this be done? Henrys are in SI base units $$\frac{kg\cdot m^2}{s^2\cdot A^2}$$.

Furthermore, I have also read about the permeability of free space, $$u_0$$. Does that come into play here?

• – alephzero Feb 11 at 8:25