An international system of electro-therapeutics : for students, general practitioners, and specialists . plate to the copper plate. Hence the zinc is calledthe positive pZa^e and the copper the negative this be kept in mind, no confusion need be causedby the paradox that the positive pole is the terminalof the negative plate and the negative pole the terminalof the positive plate. The evolution of gas at the copper plate showsthat some chemical reactions are going on in the is really taking place is, that the sulphuric acidis acting on the zinc, thus :— Zn + H2SO4 =ZuS04 + H
An international system of electro-therapeutics : for students, general practitioners, and specialists . plate to the copper plate. Hence the zinc is calledthe positive pZa^e and the copper the negative this be kept in mind, no confusion need be causedby the paradox that the positive pole is the terminalof the negative plate and the negative pole the terminalof the positive plate. The evolution of gas at the copper plate showsthat some chemical reactions are going on in the is really taking place is, that the sulphuric acidis acting on the zinc, thus :— Zn + H2SO4 =ZuS04 + H2So that hydrogen is set free, and this is the gas thatis appearing at the copper plate. The zinc sulphate that is formedremains in the liquid, while the zinc is gradually eaten away. This isthe simplest possible form of voltaic cell. 38. Magnetic Field op Force op a Current.—Wherever a magnetis subject to magnetic force there is, by § 32, a field of magneticforce. Hence a current has a magnetic field. It is a comparativelysimple problem to determine the direction of the lines of force of this. Fig. 15. ELECTRO-PHYSICS. A-25 field, , the direction of the force at any point in the field. A magnettends everywhere to set itself at right angles to the current, no matteron which side of the current it is. Hence, the lines of force are circlessurrounding the current with their centres on the current. They ma3be thought of in this way : Imagine the current surrounded by circularcylinders, the current occupying the axis. Then the lines of force arecircles, got by taking sections of the cylinder at right angles to the direction of the force along these lines of force relatiA^ely to thedirection of the current may be found by Amperes rule (§ 36), orit is more simply remembered from the rule that the direction of thecurrent is related to the positive direction of the lines of force, as thethrust to the twist in a right-handed screw. 39. Electro-magnetic Units of Current
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectuterus, bookyear1894
