TITLE:
The Nonzero External Magnetic Field of Long Solenoids
AUTHORS:
Shiwei Ye
KEYWORDS:
Solenoid, Magnetic Flux Density, Vector Potential, Aharonov-Bohm Effect
JOURNAL NAME:
Journal of Electromagnetic Analysis and Applications,
Vol.14 No.2,
February
14,
2022
ABSTRACT: A widespread assertion has existed for a long time, believing the external field of an infinitely long solenoid should be zero, but it is proofed to be wrong in this work. The components of magnetic flux density of current-carrying, closely wound cylindrical solenoids are calculated. At a distant field point, the external field definitely has a nonzero component, being equal to that of a straight wire of equal length. Since this equivalence is length-independent, it still holds true for ideal solenoids having infinite length. Hence the incorrect and still spreading inference about long solenoids should be rectified. Furthermore, theoretical and experimental discussions involving solenoids should be reviewed again carefully.