A laboratory manual of electrotherapeutics . nt. Each galvanometer should be carefully examinedto see whether the needle swings freely. If this is thecase it will come to rest in exactly the same position afterevery deflection if the instrument has not been moved. Throughout the following experiments in which elec-tric currents are to be measured, or compared, it will benecessary to so regulate the battery power as to keep thedeflection within the limits for which the instrument iscalibrated. OF ELECTROTHERAPEUTICS. GALVANOMETER CALIBRATION TABLE. Current in Current in Current in c/) MlLLIAMPE
A laboratory manual of electrotherapeutics . nt. Each galvanometer should be carefully examinedto see whether the needle swings freely. If this is thecase it will come to rest in exactly the same position afterevery deflection if the instrument has not been moved. Throughout the following experiments in which elec-tric currents are to be measured, or compared, it will benecessary to so regulate the battery power as to keep thedeflection within the limits for which the instrument iscalibrated. OF ELECTROTHERAPEUTICS. GALVANOMETER CALIBRATION TABLE. Current in Current in Current in c/) MlLLIAMPERES. en Ma. a Ma. H w a 0 0 a A Term. B Term. Ed Q A Term. B Term. Q A Term. B Term i i-5 ?25 n° 21° 55-9 2° 3 52 12° 22° 61. 15-95 3 4 5 9 13 26. 5 7-3 23 67. 4~ b 3 I 32 4° 29-5 24° 73-1 18. 5J 8 I 8 15° 25° 79-3 bu 10 2 3 lb 35-8 10 2b° 7 12 i 2 9 17 39-1 27° 94. 8^ 4 3 3 54 l8 28° 9 lb 4 4 2 19 29 10° IS 7 4 9 20° 51-2 13-93 30 Fig. 2. The Ordinary form of Milliarnperemeter. EXPERIMENTS WITH CURRENT STRENGTH. The Voltaic or Galvanic Cell (T. 168)— A com-mon and convenient method for generating a current ofelectricity is to make use of a glass or porcelain cup, con-taining a liquid, as acidulated water, in which two piecesof dissimilar metals are partially immersed. if to theupper extremities of these strips of metal, wires are at-tached and the opposite ends of the wires are connectedto the binding posts of a galvanometer, the deflection ofthe galvanometer needle will give evidence that a currentof electricity is flowing along the wires. The origin of theelectricity in this case is due to the chemical action that istaking place between the acidulated water and one of themetal strips, and is at the expense of that metal since it isgradually consumed. This is a transformation of chemi-cal energy into electrical energy. The cup and containedliquid and metals is calle
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