螺线管[Solenoid] - 达人(其实～我是卧底，来自外星)

2005/06/03 | 螺线管[Solenoid]
类别(Ω〖物理〗) | 评论(0) | 阅读(54) | 发表于 21:28: A solenoid is an inductor which is formed by a helical winding of wire around a cylindrical or toroidal core which may have a magnetic permeability associated with it.
An inductor with inductance L and current I can store magnetic energy
(1)

For an infinitely long cylindrical solenoid of radius a (which is a reasonable approximation to a long but finite cylindrical solenoid), the magnetic field is given in cgs by
(2)

where I is the current in the wire around the solenoid, N is the number of windings per unit length, c is the speed of light, and is a unit vector along the axis of the solenoid. The magnetic flux is then
(3)

so the inductance is
(4)

In MKS
(5)

where is the permeability of free space, so
(6)

and
(7); 0