478 OHM ON THE GALVANIC CIRCUIT. 



situated between two points of excitation, we then very simply 

 obtain 



^= L' 



where L denotes the entire reduced length of the circuit, and A 

 the sum of all its tensions. By means of this equation we ob- 

 tain the magnitude of the electric current of a galvanic circuit, 

 composed of any number of prismatic parts, which has acquired 

 its permanent state, which is not affected by the suri'ounding 

 atmosphere, and the single sections of which possess in all their 

 points one and the same electroscopic force ; in this category 

 are comprised the most frequently occun-ing cases, on which 

 account Ave shall dissect this result in the most careful manner. 

 Since A represents the sum of all the tensions in the circuit, 

 and L the sum of the reduced lengths of all the individual 

 parts, there results, in the first place, from the equation found, 

 the following general properties relative to the electric current 

 of the galvanic circuit. 



I. The electric current is decidedly of equal magnitude at all 

 places of a galvanic circuit, and is independent of the value 

 of the constant c, which, as we have seen, fixes the intensity 

 of the electroscopic force at a determined place. In the 

 open circuit the current ceases entirely, for in this case the 

 reduced length L acquires an infinitely great value. 



II. The magnitude of the current, in a galvanic circuit, re- 

 mains unchanged when the sum of all its tensions and its 

 entire reduced length are varied, either not at all, or in the 

 same proportion ; but it increases, the reduced length re- 

 maining the same, in proportion as the sura of the tensions 

 increases, and the sura of the tensions remaining the same, 

 in proportion as the reduced length of the circuit dimi- 

 nishes. From this general law we w-ill, moreover, particu- 

 larly deduce the following. 



1. A difference in the arrangement and distribution of the 

 individual points of excitation, by a transposition of the 

 parts of which the circuit consists, has no influence on the 

 magnitude of the current when the sum of all the tensions 

 remains the same. Thus, for instance, the current would 

 remain unaltered in a circuit formed in the order copper, 

 silver, lead, zinc, and a fluid, even when the silver and lead 



