418 Prof. Jakob Kunz : An Elementary Theory of the 



Now, if a charge having a velocity v is abruptly brought 

 to rest at 0, of fig. 2, a spherical pulse of strong electric and 

 magnetic forces will spread out with the velocity of light c. 



Fig. LV 



E 



The ratio of the two components — ' of the electric force E 



in the pulse will be equal to r 



E,= 



AB 



vt sin $ 





qvt sin 3 

 ctrS 



because r = ct 



or 



E i! =- / . and the magnetic rorce n. = cih t — — ^ 



sin 3 



is vertical on the plane of the last figure in the point A. Now 

 let the decrease of the velocity of the charge q be Av during 

 At seconds, then we have 8 = cAt and 



-j-, _Avq sin 3 _ Av q sinS 



