Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . s in Fig. 103, causes it to ap-proach the wire. This result may be shown byplacing the conducting wire in a vertical position,and presenting to it a needle suspended in a horizon-tal position by a thread. When the needle is re-moved to some distance, or when very short, theattraction becomes insensible. From the feeble mag-netizing power of the wire, this experiment is bestperformed with a needle previously charged. Ifthe needle is brought up to the w
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . s in Fig. 103, causes it to ap-proach the wire. This result may be shown byplacing the conducting wire in a vertical position,and presenting to it a needle suspended in a horizon-tal position by a thread. When the needle is re-moved to some distance, or when very short, theattraction becomes insensible. From the feeble mag-netizing power of the wire, this experiment is bestperformed with a needle previously charged. Ifthe needle is brought up to the wire with its polesin the reverse direction to those of the iron rod inFig. 104, or if, without changing their direction, it iscarried to the other side of the wire|»t is repelled bythe combined tangential forces. 259. Fig. 104 illustrates the action of the forcesin producing attraction and repulsion. W repre-sents a horizontal section of the conducting wire, inwhich the current is ascending; and N S a magnetic TANGENTIAL, FORCES. 163 needle, whose poles are at equal distances from thewire. From W, as a centre, a circle is drawn Fig. passing through the forces which movethe magnet are tangentsto this circle, and theirdirections are indicated bythe arrows. It will beseen that the resultant ofthe forces, acting on eachpole, urges the centre ofthe magnet towards thewire. If the magnet be transferred to the positionN S^ on the other side of the wire, its centre is urgedaway from it. The force increases in proportion asthe magnet is nearer to the wire. 260. When the poles are at different distancesfrom the wire, the resultant of the tangential forces „. ^^^ moves the magnet Fig. 105. , , , obliquely towards the wire, until itscentre comes intocontact with it. Ifthere are two cur-rents moving inopposite directions,•W one on each side of the magnetized bar, and at equal distances from it,their combined action urges the bar forward untilits centre comes into the sam
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
