ELECTRICAL CAPACITANCE

ELECTRICAL CAPACITANCE-

Capacitance is the ability of a body to store an electrical charge. Any object that can be electrically charged exhibits capacitance. A common form of energy storage device is a parallel-plate capacitor. In a parallel plate capacitor, capacitance is directly proportional to the surface area of the conductor plates and inversely proportional to the separation distance between the plates. If the charges on the plates are +q and −q, and Vgives the voltage between the plates, then the capacitance C is given by

which gives the voltage/current relationship

Capacitors

Capacitance is typified by a parallel plate arrangement and is defined in terms of charge storage: where Q = magnitude ofcharge stored on each plate. V = voltage applied to the plates.

Capacitor Combinations

Capacitors in parallel add ...

If =  , =  then =

Capacitors in series combine as reciprocals ...

=

Charge on Series Capacitors

Since charge cannot be added or taken away from the conductor between series capacitors, the net charge there remains zero. As can be seen from the diagram, that constrains the charge on the two capacitors to be the same in a DC situation. This charge Q is the charge you get by calculating the equivalent capacitance of the series combination and multiplying it by the applied voltage V. You store less charge on series capacitors than you would on either one of them alone with the same voltage!

Does it ever make sense to put capacitors in series? You get less capacitance and less charge storage than with either alone. It is sometimes done in electronics practice because capacitors have maximum working voltages, and with two "600 volt maximum" capacitors in series, you can increase the working voltage to 1200 volts.