| 单词 | magnetic moment |
| 释义 | magnetic moment The ratio between the maximum torque (Tmax) exerted on a magnet, current-carrying coil, or moving charge situated in a magnetic field and the strength of that field. It is thus a measure of the strength of a magnet or current-carrying coil. In the Sommerfeld approach this quantity (also called electromagnetic moment or magnetic area moment ) is Tmax/B. In the Kennelly approach the quantity (also called magnetic dipole moment ) is Tmax/H. In the case of a magnet placed in a magnetic field of field strength H, the maximum torque Tmax occurs when the axis of the magnet is perpendicular to the field. In the case of a coil of N turns and area A carrying a current I, the magnetic moment can be shown to be m = T/B = NIA or m = T/H = µNIA . Magnetic moments are measured in SI units in A m2.An orbital electron has an orbital magnetic moment IA, where I is the equivalent current as the electron moves round its orbit. It is given by I = qω/2π , where q is the electronic charge and ω is its angular velocity. The orbital magnetic moment is therefore IA = qωA/2π , where A is the orbital area. If the electron is spinning there is also a spin magnetic moment (see spin); atomic nuclei also have magnetic moments (see nuclear moment) |
| 随便看 |
|
物理辞典收录了3346条物理词条，基本涵盖了常用物理知识及物理英语单词词组的翻译及用法，是物理学习的有利工具。