Figure 27-10. Contour map of the function 



(y2 + l) ( x 2 +y 2_|_l)i/ 2 



idea of a mass particle in which we associate a mass m with a point. In 

 the magnetic problem we use the idea of a magnetic particle in which we 

 associate a magnetic moment m with a point. 



The concepts of magnetic field, magnetic moment, and magnetic particle 

 may be developed from Coulomb's law of force for magnetic poles, 



F= cM^ 



(28) 



/ - 



Here p t and p 2 represent two point magnetic poles, r the distance separating 

 them, and F the force on either arising from the presence of the other. In the 

 electromagnetic system of units c = 1 and its units are suppressed. Unit poles 



598 



