2005/04/06 | 点电荷[Point Charge]
类别(Ω〖物理〗) | 评论(0) | 阅读(43) | 发表于 15:02
A point charge is a hypothetical charge located at a single point in space. While an electron can for many purposes be considered a point charge, its size can be characterized by length scale known as the electron radius.
In cgs, the magnetic field at a point r of a slowly moving charge q at position is given by

(1)

where v is the charge's velocity and c is the speed of light, and in MKS,
(2)

The magnetic and electric fields of a moving charge are related in cgs by
(3)

and in MKS by
(4)

For relativistic speeds, from the Liénard-Wiechert potentials, it follows that

(5)


(6)

where is relativistic beta and a is the acceleration.
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