Induction- Coil Potentials. 



511 



Fig. 3. 



^ 



18 

 16 



14 



te 



10 

 8 

 6 



2 









i^Z.73 1 



A 







419,000- 

 400.000 



1 \ 









\ 







350.000- 



\ 















300 000- 

















200.000 



I 









y 







V 



I £ 3 



£//V THOUSANDTHS OF A SECOND 



Case III. 



304-4, rc 2 =1224. 



Final Experiments and Conclusions. 

 One of the experimental curves for each case is shown in 

 Plate VIII. figs. 7, 8, 9 *. In obtaining them the external 

 circuit (i. e. the battery branch) was made as nearly non- 

 inductive as possible^ the connecting wires being well twisted 

 together and the current being varied by changing the 

 number of battery cells, rather than by inserting resistance 

 coils. This was necessary because the primary condenser 

 was connected directly across the coil. If a large battery 

 and rheostat is used there is much sparking at the interr up tor, 

 and the maximum secondary potential is small and not even 

 approximately proportional to the primary current. Two 

 forms of interruptor were used, one consisting of a steel rod 

 making contact with an iron plate, the other of an amal- 

 gamated copper rod dipping into mercury, in each case under 

 paraffin oil. Even when the external circuit was nearly non- 

 inductive there was generally sparking at the interruptor with 

 the stronger currents, but occasionally a sparkless interruption 

 occurred, accompanied by an exceptionally high potential in 

 the secondary coil. The amplitude of the electrometer curve 



* The three photographs shown were obtained on different occasions, 

 on which the electrometer had different decrees of sensitiveness. 



