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 Sheet
A thin conducting sheet carries a current
density α(ampere / meter),(See Fig.9-8)
Example,Short Solonoid
See Fig,9-9
The solonoid has a length l and radius a,