The internal inductance of a straight wire of circular cross section with radius r, length l and permeability μ is

• A. \(\frac{\mu }{{2\pi }}In\left( {\frac{r}{l}} \right)H/m\)
• B. \(\frac{\mu }{{4\pi }}H/m\)
• C. \(\frac{\mu }{{8\pi }}H/m\)
• D. None of the above