Dental and oral radiography - a text book for students and practitioners of dentistry (1916) (14570786447)

Identifier: dentaloral00mcco (find matches)
Title: Dental and oral radiography : a text book for students and practitioners of dentistry
Year: 1916 (1910s)
Authors: McCoy, James David
Subjects: Radiography, Dental X-rays Teeth Mouth
Publisher: St. Louis : Mosby
Contributing Library: West Virginia University Libraries
Digitizing Sponsor: LYRASIS Members and Sloan Foundation



Text Appearing Before Image:
Fig. 9. A, magnet with diagrammatic illustration of magnetic lines of force sur-rounding it. B shows a coil of wire connected to a galvanometer, C. will show that a momentary electric current haspassed through the coil. The current continuesas long as the coil is in motion and ceases assoon as the coil is brought to rest. If the coil iswithdrawn from the magnet, a current is alsoinduced which flows in an opposite direction to 40 DENTAL AND ORAL RADIOGRAPHY the current which was induced when the coil wascarried down over the magnet. These induced currents are produced by thefield surrounding the magnet moving or cuttingacross the ivires composing the coil. If a cur-rent is passed through the coil it creates a mag-netic field, and on the other hand the movement
Text Appearing After Image:
Fig. 10. A, battery from which an electric current is passing through the sole-noid, B; C, large coil into which the smaller coil B is passed; D, galvano-meter. of a magnetic held within the coil produces a cur-rent. Asa solenoid is surrounded by a magnetic fieldsimilar to an ordinary bar magnet, it follows thatif a solenoid carrying a current were thrust with-in (Fig. 10) another coil, induced currents willbe produced in the latter. These induced cur- ELECTROMAGNETIC INDUCTION 41 rents, as in the case where the magnet is used,only flow while there is a relative movement be-tween the magnetic field and the conductor.When the solenoid is passed into the other coil,the induced current will flow in an opposite direc-tion to the current floiving in the solenoid, andupon withdrawing the solenoid, the induced cur-rent will floiv in the same direction as the cur-rent in the solenoid. Suppose the two coils just described are placedone within the other (there being no current pass-ing) and whi