Analytical Study of the Alternating Current Arc. 331 



Table II. B. 



Observations on the Periodic Variation of the Intensity of the 

 Light of an Alternating Current Arc, 



Light from Crater. Medium Are. 



Frequency = 50 ~. 



Length of arc = 063 cm. 



Potential-difference of carbons (mean 



square value) =38 volts. 



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



Power expended in arc =532 watts. 



Pressure at alternator terminals . . . =96 volts. 



Angle of 

 Phase. 



Current 



through Arc 



(instantaneous 



value). 



P.D. 



of Carbons 



(instantaneous 



value). 



Angle of 

 Phase. 



Intensity of 



Light from 



Crater of 



lower Carbon. 













20 



56 

 43 



30 



+ 63 



+17 



40 



45 



50 



- 05 



- 2-5 



60 



32 



70 



- 3-9 



-22 



80 

 100 

 120 

 140 

 160 

 180 



39 



52 

 137 



277 

 277 

 227 



190 



-11-3 





200 



165 



210 



- 5-5 



-22 



220 



63 



230 



+ 0-1 



- 1 



240 



64 



250 



+ 4-2 



+ 16 



260 



61 



270 



+11 



+284 



280 

 300 

 320 

 340 

 360 

 340 

 320 



78 

 85 

 72 

 87 



(37)? 

 ' 69 

 75 



