Analytical Study of the Alternating Current Arc. 333 



Table III. B. 



Observations on the Periodic Variation of the Intensity of the 

 Light of an A Iternating Current Arc. 



Light from Crater. Medium Arc. 



Frequency = 26 ~. 



Length of arc = 0*63 cm. 



Potential- difference (P.D.) of carbons) t «a i, 



(mean square value) ) 



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

 Power expended in arc . . . . . = 546 watts. 

 Pressure at alternator terminals . . =62 volts. 



Angle of 

 Phase. 



Current 



through Arc 



(instantaneous 



value). 



P.D. 



of Carbons 



(instantaneous 



value.) 



Intensity of 



Light from 



Crater of 



lower Carbon. 







+ 18 



+52 



64 



20 



+14-3 



+55 



77 



40 



4- 6-7 



+24-5 



46 



60 



4 1 



+ 4-5 



42 



80 



- 12 



-21 



43 



100 



- 5 



-27 



52 



120 



-17-5 



-37 



64 



140 



-18-2 



-47 



145 



160 



-20-6 



-52 



285 



180 



-20 



-54 



310 



200 



-11 



-47 



260 



220 



- 5 



-255 



200 



240 



- 1 



- 5-5 



119 



260 



+ 2 



+15 



87 



280 



+ 8-5 



+30 



50 



300 



+14 



+40 



104 



320 



+ 19 



+45 



110 



340 



+22 



+53 



130 



360 



+21 





120 



Phil. Mag. S. 5. Yol. 41. No. 251. April 1896, 2 A 



