4 6 



ELEMENTS OF ELECTRICITY AND MAGNETISM. 



vidual cells. Figure 22 is a top view of three dry cells connected 

 in series and delivering current to a circuit R. 



A number of voltaic cells of the same kind are often connected 

 in parallel. When this is done the total current delivered by the 

 set is equal to the sum of the currents delivered by the individual 



Fig. 22. 



Fig. 23. 



cells, and the electromotive force of the set is the same as the 

 electromotive force of a single cell. Figure 23 is a top view of 

 three dry cells connected in parallel and delivering current to a 

 circuit R. 



Sometimes it is desirable to connect a number of cells in groups, 

 each group containing a number of cells in series, and to connect 



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R 



, Fig. 24. 



these groups of cells in parallel. Figure 24 is a top view showing 

 two groups of dry cells connected in parallel, each group consist- 

 ing of four cells connected in series. 



24. Discussion of the division of current in two branches of 

 a circuit. Figure 25 shows a battery delivering current to a 

 circuit which branches at the points A and B. Let / be the 

 current in the main circuit, /' the current in the upper branch, 



