\-24 EXPERIMENT IN MAGNETO-ELECTRIC INDUCTION. 



The quantity of the alternating current is determined by A ; and the value 

 of a only affects the epoch of the maximum current. If we make p = 0, the 

 effect is that of closing the circuit of x, and we find 



,. 

 " 



This expression shews that the condenser has no effect when the current 

 is closed. 



If we make p = <, the effect is that of removing the conductor y, and 

 thus breaking the circuit. In this case 



JfV 



Tliis expression gives a greater value of A than when the circuit is closed, 

 provided ZCLn* is greater than unity, which may be ensured by increasing the 

 capacity of the condenser, the self-induction of the electromagnetic coil, or the 

 velocity of rotation. 



If CL?R = \, the expression is reduced to 



_Mn 

 '~R- 



This is the greatest effect which can be produced with a given velocity, and 

 is the same as if the current in the coil had no "electromagnetic momentum.' 



If the electromagnet has a secondary coil outside the primary coil so as 

 to form an ordinary induction-coil, the intensity of the secondary current will 

 depend essentially on that of the primary which has just been found. Although 

 the reaction of the secondary current on the primary coil will introduce a 

 greater complication in the mathematical expressions, the remarkable phenomenon 

 described by Mr Grove does not require us to enter into this calculation, as 

 the secondary sparks observed by him are a mere indication of what takes 

 place in the primary coil. 



