Abstract :
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.
