The outlines of physics: an elementary text-book . ducior, moving in the magneticfield, meets with resistance to its motion, may be demon-strated in numerous ways. One ofthe simplest experiments for this pur-pose consists in mounting a pendulumof the form shown in Fig. 286 be-tween the poles of an long as the magnet is inactive, thiscopper pendulum swings freely. If,however, the current be sent throughthe coils of the magnet, thus creatinga strong field, the copper pendulumwill experience such resistance to itspassage across the lines of force thatit will be brought to rest be
The outlines of physics: an elementary text-book . ducior, moving in the magneticfield, meets with resistance to its motion, may be demon-strated in numerous ways. One ofthe simplest experiments for this pur-pose consists in mounting a pendulumof the form shown in Fig. 286 be-tween the poles of an long as the magnet is inactive, thiscopper pendulum swings freely. If,however, the current be sent throughthe coils of the magnet, thus creatinga strong field, the copper pendulumwill experience such resistance to itspassage across the lines of force thatit will be brought to rest before itcompletes a single vibration. Theexperiment is a striking one and may be easily tried; it isinstructive to attempt to move the sheet of copper sud-denly in the field by means of the hand. The resistancewhich manifests itself may then be directlyfelt. If a second copper disk similar to thefirst, but cut nearly through, with theshears in a series of vertical slits, as shown in Fig. 287,be substituted for the pendulum above described, it will. Fig. 286. Fig. 287. 324 THE OUTLINES OF PHYSICS be found that it experiences comparatively little opposi-tion when swinging in the magnetic field. The reason isthat the vertical slits in the copper interfere with the cir-culation of the induced currents. These being less power-ful, comparatively few lines of force are formed round themoving mass. Such a pendulum will make several vibra-tions in the field of the electromagnet before comingto rest. 294. Force exerted upon a Wire carrying Current in theMagnetic Field. — The phenomenon described in the first ^^ article of this chapter is ^0-5** a reversible one. Any ^^o^j?r wire placed in a mag- — ^ * netic field in such a * position that it is not parallel to the lines of force, and which has a current flowing DOWNWARD through it, is acted FORCE ACTING „ 1 • 1 UPON THE WIRE upou by a force which t^nds to move it atj,jQ 288 right angles to its own length, and to the direc-tion of
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectphysics
