File:A manual of practical medical electricity - the Röntgen rays and Finsen light (1902) (14596966570).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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lectricity of opposite electromotive force that it hasstored up, and of strengthening it at opening by makingthe break more sudden and complete. The extra currentis usually collected in medical coils, and used as the primary current (Fig. 68). We have seen that in the secondary coil there is induceda momentary current in the opposite direction at closingthe primary circuit, and one in the same direction atopening. During the continuous flow of the current in theprimary there is no observable current in the secondary. 114 A Manual of Practical Medical Electricity The opening current in the secondaiy is more powerfulthan the closing, and this for two reasons : 1. The galvanic current in the primary coil does not atonce attain its full strength on closing, particularly if acondenser be used. 2. The freshly-induced extra current opposes the estab-lishment of the primary current. But when the primary current is opened, it is both atits own full intensity, and it is also strengthened by the
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Patient Fig. 68.—Diagram of Method of Collecting the Primary Current. extra current, and hence it has a much more powerfuleffect upon the secondary. What we have observed maybe tabulated as follows : Momentary currents of opposite E. M. F. are inducedin a closed circuit by 1. The approach of a magnet. 2. The magnetization of an electro-magnet lying nearthe circuit. 3. The approach of a wire conveying a current. Faradic Electkicity 115 4. The making of a current in a neighbouring wire. 5. The increasing of the strength of that current. And, vice versa, momentary currents of similarE. M. F. are induced in a circuit by 1. The recession or demagnetization of a magnet. 2. The recession of a wire carrying a current. 3. The breaking of the current in a neighbouring wire,or the decreasing in strength of such a current. The Induction Coil. The induction coil is constructed upon these principles.It may be regarded as an arrangement for producing aninduced current of high E. M. F., by the indu

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