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Capacity of a Condenser

It is found by experiment that the charge required to produce a certain difference of potential between the plates of a condenser bears a constant ratio to the difference of potential. This constant ratio is called the capacity of the condenser.

Thus if the charge be Q, the difference of potential between the plates V, and the capacity C, we have, from the above definition,

The capacity, as has been said, depends on the geometrical form of the condenser and the nature of the insulating medium. If the condenser take the form of two large flat plates, separated by a short interval, the capacity is approximately proportional to the area of the plates directly, and to the distance between them inversely.

Condensers of large capacity are frequently made of a large number of sheets of tin foil, separated from each other by thin sheets of mica. The alternate sheets 1, 3, 5, &c., are connected together and form one plate; the other set of alternate sheets, 2, 4, 6, &c., being connected together to form the other plate. Sheets of paraffined paper are sometimes used instead of mica.

Last Update: 2011-03-19