Table 1 Formulas approximate for how many turns are required to achieve a specified inductance

$\mathit{L}={\mathit{N}}^2\mathit{R}{\mu }_0{\mu }_{\mathit{r}}\left[\mathit{ln}\left(\frac{8\mathit{R}}{\mathit{a}}\right)-0.2\right]$

[62]

$\mathit{L}=\frac{{\mathit{r}}^2{\mathit{N}}^2}{\left(2\mathit{r}+2.8\mathit{d}\right)*{10}^3}$

[63]

$\mathit{L}=\frac{0.31{\left(\mathit{aN}\right)}^2}{6\mathit{a}+9\mathit{h}+10\mathit{b}}$

[64]

$\mathit{L}=2.9\mathit{ln}\left(\frac{9}{\mathit{D}}-\mathit{K}\right){\mathit{N}}^{1.9}$

[65]