Electrical measurementsA laboratory manual . ough them is accompanied by the decompositionof the liquid conductor. If the rate of decompositionexceeds the rate of diffusion of the ions or products ofthe electrolysis, so that they accumulate on the elec-trodes, the result is a counter of interferes with the measurement of electro-lytic resistances by the most simple means. The mostusual method of annulling its effect is to employ rapidreversals of current or an alternating current of hip^hfrequency. For this purpose a double commutator on one shaft is 110 ELECTRI
Electrical measurementsA laboratory manual . ough them is accompanied by the decompositionof the liquid conductor. If the rate of decompositionexceeds the rate of diffusion of the ions or products ofthe electrolysis, so that they accumulate on the elec-trodes, the result is a counter of interferes with the measurement of electro-lytic resistances by the most simple means. The mostusual method of annulling its effect is to employ rapidreversals of current or an alternating current of hip^hfrequency. For this purpose a double commutator on one shaft is 110 ELECTRICAL MEASUREMENTS. appKcable. The shaft should be capable of rapid rota-tion by means of a crank and a train of gears. Onecommutator is included in the battery circuit and theother in that of the galvanometer. They should be setso that the current is reversed through the liquid at thesame time that the galvanometer is commuted. Thecurrent reversals are supposed to be so frequent thatpolarization is annulled. The apparatus is shown inFig. Fig. 47. For the purpose of relative measurement of resistanceor conductivity, comparison or standard solutions areneeded. The following are recommended by F. Kohl-rausch ^ as good conducting solutions, having a conduc-tivity denoted by k at the temperature of t degrees C: NaCl, per cent, sp. gr. = 2015 X 10-^^ + 45 X 10- G - 18)-MgSO^^ per cent, sp. gr. ^ = 460 X 10-^ + 12 X 10^ (t- 18). 1 Wied. Ann. II., p. 653, 1880; Fh2/s. Jfeas., p. 320. BESISTANCE. Ill
Size: 2073px × 1205px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1890, bookpublisherbosto, bookyear1895
