Capacitors, Magnetic Circuits, and Transformers is a free introductory textbook on the physics of capacitors, coils, and transformers. See the editorial for more information....


The progress of man has been in almost direct proportion to his utilization of solar energy. Solar energy exists in chemical form in fossil fuels as well as in potential and kinetic form in waterfalls and in the flow of rivers. In the case of fossil fuels the sun's energy promotes the growth of plant life. This is followed by a long period of decomposition of the plants into fuels such as coal, oil, and gas. The process of storing energy in water that evaporates from the sea and other bodies, and then falls as rain on mountain slopes, maintaining waterfalls and flow of rivers, is a continuing one. Man has become highly skilled in the control and use of large amounts of energy to do his work for him. He has also acquired great skill and knowledge in developing means for detecting and amplifying minute amounts of power. The progress made in the understanding, development, and use of energy during the twentieth century exceeds all the previous progress made by man. This tremendous progress has been brought about largely by the electrical industry which had its beginnings about a century ago.

The birth of new industries and the accelerated growth of young industries has made and is continuing to make large demands on the electric power production facilities. Since the turn of the century giant industries such as radio, television, and commercial aviation have developed. The automobile industry has achieved tremendous growth since that time as well. The development of the electronic computer, along with the development of atomic and nuclear energy, gave a much greater impetus to the world's industrial, and consequently, economic development than did the industrial revolution of the eighteenth century. The modern trend is not only toward the utilization of more energy at greater efficiency but also toward the detection and use for control purposes of smaller and smaller quantities of energy.

The extreme sensitivities and great speeds of response of electronic devices have had a tremendous influence not only upon manufacturing processes but even on medical practices. We are therefore concerned with energy conversion in its large scale eifects as well as in its minutest manifestations.

Last Update: 2011-02-16