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Condensers

المؤلف:  GEORGE A. HOADLEY

المصدر:  ESSENTIALS OF PHYSICS

الجزء والصفحة:  p-332

2025-11-27

466

The principle -of induction is used to give to a body a much greater charge than it would otherwise receive.

Demonstration. - Cut out a sheet of tin foil six inches square and place it in the middle of a pane of glass a foot square. Count the number of sparks that you can make pass from the electrophorus disk to the square of tin foil. Discharge the tin foil by touching it. Lift the glass plate from the table and place under it a second sheet of tin foil connected with the earth. Count the number of sparks that you can now make pass into the upper tin foil. Touch the lower tin foil with one hand, and the Ο upper tin foil with the other. How does the spark differ from the ordinary?

The simple instrument used in the above demonstration contains all that is essential in a condenser, namely, two conductors separated by a dielectric. The reason for using a condenser is that we may increase the quantity of electricity without increasing the potential. The quantity of electricity that can be stored on each conductor is directly proportional to its area and inversely proportional to the thickness of the dielectric between the conductors. …..

 A convenient form of condenser of large capacity can be made by arranging two sets of sheets of tin foil as in Fig. 1, and separating them by putting sheets of mica, or paper soaked in melted paraffin, between them.