ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 1
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
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