平行线[Parallel Wires] - 达人(其实～我是卧底，来自外星)

2005/05/09 | 平行线[Parallel Wires]
类别(Ω〖物理〗) | 评论(0) | 阅读(55) | 发表于 12:59: Parallel wires carrying current in the same direction attract, and in the opposite direction repel. In cgs, the Biot-Savart law gives
(1)

where r is the radius of a loop around the first wire, B is the radial magnetic field strength, c is the speed of light, and is the current. The Lorentz force for a charge q traveling at speed v in a magnetic field of strength B is given by
(2)

so the differential force is given by
(3)

and the force per unit length of wire is
(4)

In MKS the Biot-Savart law gives
(5)

where is the permeability of free space, and the Lorentz force is
(6)

so
(7)

and the force per unit length of wire is
(8); 0