Analytical Study of the Alternating Current Arc. 337 



Table V. B. 



Observations on the Periodic Variation of the Intensity of the 

 Light of an Alternating Current Arc. 



Light from Crater. Long Arc. 



Frequency = 50 ^. 



Length of arc = 1*2 cm. 



Potential-difference (P.E.) of carbons ") _ ^q i, 



(mean square value) j ~ 



Current (mean square value) . . . = 14 amperes. 

 Power expended in arc ..... 742 watts. 

 Pressure at alternator terminals . . = 93 volts. 



Angle of 

 Phase. 



Current 



through Arc 



(instantaneous 



value). 



Angle of 

 Phase. 



Intensity of 



Light from 



Crater of 



lower Carbon. 









35.9 



92 



20 



+ 15-9 



18 



92 



40 



4-11-7 



36 



98 



60 



+ 1-6 



53 



84 



80 



- 4-4 



70 



70 



100 





87 



76 



120 





105 



74 



140 





123 



207 



160 





142 



175 



180 





160 



280 



200 





179 



265 



220 



- 65 



199 



193 



240 



00 



218 



76 



260 



+ 4-4 



238 



84 



280 



+ 10-4 



257 



71 



300 





277 



66 



320 





296 



101 



340 





315 



98 



360 





334 



107 







340 



120 



