] 893.] Circuits of Measurable Inductance and Capacity, fyc. 9 

 In the former case it becomes finally 



Q = 



- ml 



2n 



'here m = -=- 



2L 



and 



In the second case let p 2 = n\ and the solution is 

 Q = Q o6 - w 'sec . cos 



__ 

 where RS 



Calculating and plotting the curve for the case in fig. 2 on the 

 assumption that p is equal to the wire resistance in the circuit 

 (28 ohms), the dotted curve in the same figure is obtained. The 

 time periods of the two agree very well ; but a marked difference is 

 seen in the rate of shrinkage of the ordinates. 



The explanation that offered itself is that the wire circuit is not 

 the only seat of dissipation of energy, but that dissipation also takes 

 place in the dielectric of the condenser. In accordance with this, it 

 is possible to reproduce the experimental curve by increasing the 

 value of p to 59'43 ohms. Points on the curve so determined are 

 shown as solid dots in the figure. The agreement of the time periods 

 is also improved by this increase in />, as can be seen from the following 



table : 



Calculated from Calculated from 



p = 28. p = 59-43. Observed. 



Time period in seconds 0'009116 0-009154 0'009147 



The experiment has also been repeated with soft iron rods inserted 

 in the coil. These are rather longer than the coils, and their diameters 

 are 



No. I 1-93 cm. 



No, II 1-30 



No. Ill 0-65 



The other data were the same as for fig. 2. The curves obtained 

 are shown in fig. 3, and are numbered I, II, III, according to the rod 

 employed. Their chief characteristics are 



a. A change in time period as the discharge progresses. 



ft. Rapid decrement. 



