File:A manual of practical medical electricity - the Röntgen rays and Finsen light (1902) (14783674175).jpg

Identifier: manualofpractica00turn (find matches)
Title: A manual of practical medical electricity : the Röntgen rays and Finsen light
Year: 1902 (1900s)
Authors: Turner, Dawson
Subjects: X-Rays Electrophysiology Electrosurgery Electric Stimulation Therapy Electrotherapeutics X-rays Electrophysiology Electrosurgery
Publisher: New York : William Wood & Company
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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Fig. 66.—Current in Opposite Direction at Closing. coil is made to approach to and recede from the secondarythe stronger will be the induced current. If a core of soft iron be placed within the primarycoil, it will be found that the induced current is againstrengthened, for as the core becomes magnetized by thecurrent in the primary, we are now adding on to the in-ducing action of our primary current the inducing actionof a magnet also. (The permeability of the iron coreleads to a concentration of the magnetic lines of force.) 112 A Manual of Practical Medical Elfxtricity The current that is induced in the secondary circuit isin the opposite direction to the primary current at making,but in the same direction at breaking. K glance at the two diagrams (Figs. 66 and 67) willmake this plainer ; the circuit P is the primary one, andit includes a battery, a galvanometer, and a key. The
Text Appearing After Image:
Fig. 67.—Current in same Direction at Opening. circuit S is the secondary, and it includes a galvano-meter. In Fig. 66 the current is represented as beingmade, and in Fig. 67 as being broken ; and it will beobserved from the direction of the arrows, as well as fromthe galvanometric deflections, that the two currents, in-ducing and induced, are opposed to each other at making,but are in the same direction at breaking. Faradic Electricity 113 Faradays law is as follows : If any conducting circuit be placed in the magneticfield of a permanent magnet or of an electric current, then,if by either a change of relative position or a change ofstrength of primary current a change is made in thenumber of lines of force passing through the secondary, anelectromotive force is set up in the secondary proportionalto the rate at which the number of included lines of forceis varying. The direction of the current induced in the secondary isexplained by Lenzs law. In all cases of electro-magneticinduc

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