title: Magnetic Core Selection for Transformers and Inductors: A User's Guide to Practice and Specifications, Second Edition (Electrical and Computer Engineering)
author: Colonel Wm. T. McLyman
description: Colonel Wm. T. McLyman is the President of KG Magnetics, Inc., in San Marino, California.
zlib_text:  
   
   
  CHAPTER  10    
   
   
   
   
   
   
   
   
   
   
   
   
  Inductors 
   
   
  ELECTROMAGNETS AND GENERATORS 
    
  The reader probably remembers from previous courses in general science that an 
  electric current going through a wire will produce magnetism.  The "magnetic 
  field" is around the wire, somewhat like an invisible tube.  This is shown 
  diagrammatically by the two circles at the upper left of Fig. 10.1.  When the wire 
  is coiled, as at the right-hand side of the figure, the fields line up to make a  
   
                                     Wire
  Magnetic
  Fields
   
   
  Fig. 10.1   Magnetic fields (dashed lines) around current-carrying wire.  
   
  "donut" or "toroid" of magnetic fields, much stronger than the fields around the 
  single wire portions. 
   
  If an iron rod (not shown in the diagram) is poked vertically down through the 
  coil, the fields can go through that iron much easier than through air or vacuum.   
   
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