302 BEIJ. SYSTEM TECHNICAL JOURNAL 



Iween magnetized bodies. In the latter case, the two kinds of electrostatic 

 charge are replaced by north-seeking and south-seeking magnetic poles re- 

 spectively. Similarly the tubes of electric force are replaced by tubes of 

 magnetic force. Roughly speaking, the two kinds of tubes are endowed with 

 analogous properties. Because these magnetic lines are at rest, it is appro- 

 priate to speak of them as magnetostatic lines of force and consider them as 

 being comparable but of course not identical with electrostatic lines already 

 discussed. The force exerted on a unit magnetic pole is a measure of magnetic 

 intensity H. Like its electric counterpart, it is a vector quantity. In the par- 



Fig. 6.1-1. Arraiigemenl of lines of electrostatic force in the region between two oppositely 



charged spheres. 



■* 1 — r'v. 



? 



Fig. 6.1-2. .\rrangcment of lines of magnetostatic force in the region between two 

 o])l)ositely magnetized poles. 



ticular system of units u.sed in this text, it is measured in amjicres i)er meter. 

 Figure 6.1-2 illustrates the arrangement of the lines of magnetic force that 

 are assumed to exist between two opposite magnetic poles. 



Interrelationship of Electric and Magnetic Fields 



As a result of the electromagnetic theory, there are certain properties with 

 which we may endow lines of electric and magnetic force and thereby ex- 

 ])lain numerous jihenomena of clcclrical transmission. This establishes a 

 relationship between electric and magnetic llelds that makes them appear 



