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Chapter 18 Magnetic fields

 

Chapter 18 begins with a study of permanent magnets.  To help to understand long straight magnets (analogous to long straight bar electrets in the previous chapter) the model of a ‘magnetic pole’ is introduced.  Despite that fact thar free magnetic poles do not exist, the model proves very useful in setting up a formalism for magnetostatics. The strength of such pole is defined and is used to define the concept of magnetic field strength.  Two, essentially equivalent, fundamental laws (Ampère and Biot-Savart) are presented which can be used, in principle at least, to determine the magnetic field strength at a point due to any configuration of electric current(s).

The concepts of magnetic flux and magnetic flux density are defined and the relationship of the latter with the magnetic field strength at a point in a magnetic field is investigated.  This leads on to a discussion of the forces between permanent magnets and of Gauss’ law for magnetism.

 

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Chapter 18 problems

 

Answers to Chapter 18 problems

Understanding Physics

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