A text-book on the elements of physics; for high schools and academics

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 Excerpt: ...each other as practicable, and by employing large plates, and thereby increasing the size of the liquid conductor. But it is not always convenient to emplo-very large plates, or we may have occasion to employ a battery for certain purposes, as we shall see presently, in which large cells would be of little or no advantage. The same result that can be produced by a single pair of large plates, may be obtained by connecting the similar _ 143 plates of several pairs in separate cells, thereby practically reducing several pairs to one pair having an area equal to the sum of the areas of the several pairs. Figure 143 illustrates a method of connecting cells for the purpose of reducing the internal resistance. This is called arranging cells parallel, in multiple arc, or abreast. This arrangement is very effectual in increasing the current-strength when the internal resistance is the principal one to be overcome. For instance, call the electro-motive force (E) of a single cell 1 volt, its internal resistance 5 ohms, and let the plates be connected by a short, thick wire, whose resistance may be regarded as nothing; then F 1 C=--=-=.2 ampere. Now connect 10 similar r 5 cells abreast. The size of the liquid conductor being increased tenfold, the internal resistance is one-tenth E as large, and we have C =-= l-s-j% = 2 amperes. So that, (when there is noeeraaI_jesistance, the current increases as the size of the plates is increased. The same is approximately true in case the external resistance is very small in comparison with the internal resistance. Again, let E= 1, r = 5 ohms, as above, but the external re 1 sistance R = 200 ohms; then C: 10 pairs are connected abreast, C =--i + 200 In this case, the current is scarcely affected by increasing the number of cells a...