FIGURE 30. CIRCUIT SYMBOLS FOR CAPACITORS.

c. *The Farad*. Capacitance is measured in units called FARADS.

A onefarad capacitor stores one coulomb (a unit of charge (Q)

equal to 6.28 x 1018 electrons) of charge when a potential of 1

volt is applied across the terminals of the capacitor. This can

be expressed by the formula:

Q (coulombs)

C (farads) =

F (volts)

The farad is a very large unit of measurement of capacitance.

For convenience, the microfarad or the picofarad is used. One

microfarad is equal to 0.000001 farad or 1 x 106 farad, and 1.0

picofarad is equal to 0.000000000001 farad or 1.0 x 1012 farad.

Capacitance is a physical property of the capacitor and does not

depend on circuit characteristics of voltage, current, and

resistance. A given capacitor always has the same value of

capacitance (farads) in a circuit as in any other circuit in

which it is connected.

d. *Factors Affecting the Value of Capacitance*. The value of

capacitance of a capacitor depends on three factors: the area

of the plates, the distance between the plates, and the

dielectric constant of the material between the plates.

(1) *The Area of the Plates*. PLATE AREA affects the value of

capacitance in the same manner that the size of a container

affects the amount of water