Chapter 9 Magnetic Fields:II

Ampere’s Circuital Law Example:Long Cylindrical Conductor Example:Toroidal Coil Example:Refraction of Lines of B at

a Current Sheet Short Solenoid The Curl of B

In many cases the same current crosses the surface bounded by the curve C several times. See Fig. 9-2(b) for a solenoid.Then the total current is I×N.

Example: Long Solonoid (see Figs. 9-6 and 9-7 ）

It is very long so that the end effects will negligible.Choose a cylindrical coordinates.

Example: Refraction of Lines of B at a

Current SheetA thin conducting sheet carries a current density α(ampere / meter). (See Fig.9-8)

Example: Short SolonoidSee Fig. 9-9The solonoid has a length l and radius a.