UNIVERSITY OF COLORADO STUDIES 



Although we cannot say that the above is a logical proof, yet we 

 may say it suggests the hypothesis that a displacement current 

 of electricity is the motion of electrons just as a conduction current 

 is. In fact such a hypothesis leads to a very interesting mental 

 picture of Maxwell's dielectric displacement of electricity, such 

 displacement being nothing more nor less than the actual dis- 

 placement of the electrons in the dielectric. 



To fix our ideas let us take a particular case. Suppose that we 

 have a condenser K, and that we charge this by joining up a cell, as 

 in Fig. 2. We will suppose that there 

 are pairs of charged electrons in the di- 

 electric between the plates. During the 

 flow of the current into the plates, a num- 

 ber of + charged electrons pass into A. 

 Owing to their forces of attraction and 

 repulsion they tend to push the positive 

 electrons of each pair in the dielectric 

 from the plate A toward B, and to pull 

 the negative from B toward A. Thus 

 while the charging lasts there is an actual 

 motion of positively charged electrons 

 from A to B and negatively charged electrons from B to A, which 

 motion produces exactly the same magnetic effect as the equivalent 

 conduction current would produce, and is a real current of electricity. 

 There are, however, very few dissociated electrons in the dielectric; 

 that is, very few electrons that are free to move completely across, 

 and carry the current conductively from A to B. The result is, 

 therefore, that the charging will continue only until the electrons 

 have been forced so far from the original positions of equilibrium 

 that their mutual attractions can withstand the electro -motive force 

 of the cell, and prevent any further motion. Under these circum- 

 stances the condenser is charged. The positive electron of each 

 pair has been pushed toward B and the negative toward A; in other 

 words, the dielectric is polarized. 



Fig. 2. 



