The inductance of linear conductors of rectangular section

A short approximate formula for estimating the inductance of parallel linear conductors of rectangular section is developed. This formula is shown, theoretically and experimentally, to be reliable to within 2 per cent, provided that the length of the conductors is great compared with their section and spacing. An additional formula is put forward for estimating the end effect in those cases where the conductors cannot be assumed to be infinitely long. As the spacing between the lead and return conductors increases, the approximate formula approaches asymptotically to the theoretical formula from which it was developed. If this spacing exceeds half the perimeter of either conductor the difference between the approximate formula and the theoretical formula is less than ¿ per cent.