The outlines of physics: an elementary text-book . action between the lines of force ofthe two fields. It is as though lines of force running inthe same direction tended to repel each other. If themagnet have freedom of motion, it will tend to set itselfin such a position that its lines of force are parallel tothose which surround the current. This action, whichmay readily be shown by means of the floating needle,forms the basis for the instrument known as the galva-nometer. It is well illustrated by means of the followingexperiment: 242. Experiment 74. — magnetic Influence of a Wire, carrying
The outlines of physics: an elementary text-book . action between the lines of force ofthe two fields. It is as though lines of force running inthe same direction tended to repel each other. If themagnet have freedom of motion, it will tend to set itselfin such a position that its lines of force are parallel tothose which surround the current. This action, whichmay readily be shown by means of the floating needle,forms the basis for the instrument known as the galva-nometer. It is well illustrated by means of the followingexperiment: 242. Experiment 74. — magnetic Influence of a Wire, carryingCurrent, upon a Floating Needle. Apparatus: (1) The floating needle previously described, a cell of battery,three or four meters of copper wire. Procedure: (a) Connect the wire to the terminals of the battery, and holdabout a half meter of the intervening portion of the same in thehands. Bring this part of the wire near to the needle, holding itabove the latter in a horizontal position, and as nearly as possible in 278 TSJE OUTLINES OF PHYSICS. Fig. 242. a north and south plane. Note that the needle is deflected from itsnorth and south position in the earths field. The direction towards which the north-seeking pole tends is east erly or westerly, according to thedirection in which the current flowsthrough the wire. If the currentflows toward the north, that is tosay, if the end of the wire which istowards the south is attached to thecopper terminal of the battery, andthe northerly end to the zinc ter-minal (see Fig. 242), the north-seeking end of the floating needlewill tend to point towards the the current is reversed, the north-seeking pole will point towardthe east. But for the forces due to the earths field, the magneticneedle would always point directly at rightangles to the wire which carries the account of the earths magnetism itcomes to rest, however, in the positionwhere the forces of the earths field areprecisely balanced by those due to the actio
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectphysics
