Elementary electrical engineering in theory and practice; a class book for junior and senior students and working electricians - Softcover
Synopsis
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. 1906 Excerpt: ...resistance is diminished, but the total e.m.f. of the battery is only that of the number of cells in series in each set. Suppose we put six Daniell cells in parallel, what is the current and voltage? We gave what this is with them joined in series. First find the internal resistance of all the cells in parallel by the formula (see Munro (t wo v R. and Jamieson's "Pocket-Book"), where ns = the number nq of cells in series in each set, R = the internal resistance of each cell, and w = the number of sets in parallel." Then--ns x R 3x4,,. = = bo. nq 2 Again--E 1 x 3 3 A,. c = =---=--= 0-3 ampere. R + r 6 + 4 10 ' So the current is greater, but the voltage less, than before. The internal resistance of a cell varies inversely with the size of plates and the distance between them. So, if we double the size of plates, we halve the resistance and increase the current strength. This is also got by joining the cells in parallel: then current increases, but the voltage falls. The arrangement to give the strongest current strength with any number of cells is when the internal resistance equals the external resistance. The grouping of a number of cells together is called a battery. This may be a primary, or a secondary one, according as the cells are primary or secondary which compose it. II. Storage Cells.--There are many different types of cells in the market--such as the Tudor, the Chloride, the Lithanode, the E.P.S. cells; but for a detailed description of these the student should consult an advanced text-book. A secondary battery or storage cell requires current to be sent through it from a continuous-current machine to render it active, and then it will, after being charged, supply current when the + plate is joined to the (-) plate till the discharg...
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