203 



Electromagnetic Induction in Conductors of Different 

 Materials and in Electrolytes. 



Arthur L. Foley and Chester A. Evans. 



This investigation was uudertalven tor the purpose of determining 

 whether or not the character of a conductor has any effect upon the 

 electro-motive force generated in it when i( is made to cut magnetic lines 

 of force. 



Is the e. m. f. generated in a copper wire of given length exactly equal 

 to the e. m. f. generated in a silver wire of the same length when both 

 cut lines of force at the same rate? And is this e. m. f. equal to that 

 generated in a nonconducting tube of length 1. tilled with an electrolyte, 

 when the electrolyte is made to cut lines of force at the above rate? 

 Electrolytic conduction and metallic conduction appear to be very dif- 

 ferent processes, why then should one expect metals and electrolytes 

 to give identical results from electromagnetic induction? 



It is evident that many difficulties and somx-es of error will be 

 avoided if the two conductors to be tested can l)e placed together and 

 made to cut the same held in such a manner that the resultant e. m. f. 

 generated is zero, provided that electromagnetic induction is independent 

 of the substance of the conductor. Also, the direction of the e. m. f. 

 must be constant if a sensitive galvanometer is to be used to detect it. 



Fig. 1. 



Let M (Fig. 1) be a cylindrical magnet mounted to revolve about its 

 axis, and let w and w^ be wires in contact respectively with the middle of 

 the magnet and the center of the end. and connected, as shown, to a gal- 



