The computation of magnetic field strength of round coils of small cross section

WHEN a solenoid, or cylindrical coil, has no iron core, the magnetic field in the space around it or within it may be come used very precised. Formulas have been published¹ which take account of the length and thickness of the coil by algebra terms which have been obtained by an integration over the cross section of the coil. This requires a calculation to be made twice, once for the end of the coil nearer the point for which the magnetic field is being computed, and once for the farther end.