Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . ELECTRO-MAGNET, IN FRAME. 185 For the purpose of showing its lifting power, theelectro-magnet is made of the U form, (Fig. 126.)The battery with which it is used should be in pro-portion to the length and fineness of the wire, inorder to obtain the greatest power. With a thickand rather short wire, a battery of one or two pairswill be preferable. With a long and fine wire, anumber of pairs should be employed. A small elec-tro-magnet will sustain a lar
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . ELECTRO-MAGNET, IN FRAME. 185 For the purpose of showing its lifting power, theelectro-magnet is made of the U form, (Fig. 126.)The battery with which it is used should be in pro-portion to the length and fineness of the wire, inorder to obtain the greatest power. With a thickand rather short wire, a battery of one or two pairswill be preferable. With a long and fine wire, anumber of pairs should be employed. A small elec-tro-magnet will sustain a large mass of iron nails orfilings about its poles, which fall when the flow ofthe current is stopped. 296. Electro-Magnet, in Frame. — Fig. 127 Fig. represents an electro-magnet, fixed in a frame, for tho16* 186 DAVISS MANUAL. purpose of supporting heavy weights. The arma-ture, Aj consists of a semicircular piece of the , this form is preferable to astraight bar. If the iron of the magnet is soft andpure, its magnetic power is immediately communi-cated and lost, according as the connection with thebattery is made or broken. When, however, thearmature is applied to the poles, and the flow of thecurrent stopped while it is attached, it will continueto adhere for weeks or months with great force, so asto be able to sustain one third or one half as muchweight as while the current was circulating. But ifthe keeper be once removed, nearly the whole mag-netism disappears, and the magnet, if of good iron,will not even be able to lift an ounce. The purestiron retains, for a time, a certain amount of mag-netic power, after being strongly magnetized, evenwhen an armature is not applied. This amountincreases with the s
Size: 1478px × 1691px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
