ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 1
(2) Discharging. To DISCHARGE a capacitor, the charges on the
two plates must he neutralized. This is accomplished by
providing a conducting path between the two plates as shown in
figure 33, view B, on the previous page. With the switch in
position (4), the excess electrons on the negative plate can
flow to the positive plate and neutralize its charge. When the
capacitor is discharged, the distorted orbits of the electrons
in the dielectric return to their normal positions and the
stored energy is returned to the circuit. It is important to
note that a capacitor does not consume power. The energy the
capacitor draws from the source is recovered when the capacitor
is discharged.
h. Charge and Discharge of a Resistance Capacitance (RC) Series
Circuit. Ohm's law states that the voltage across a resistance
is equal to the current through the resistance times the value
of the resistance. This means that a voltage is developed
across a resistance ONLY WHEN CURRENT FLOWS through the
resistance.
A capacitor is capable of storing or holding a charge of
electrons. When uncharged, both plates of the capacitor contain
essentially the same number of electrons. When charged, one
plate contains more free electrons than the other plate. e
difference in the number of electrons is a measure of the charge
on the capacitor. The accumulation of this charge builds up a
voltage across the terminals of the capacitor, and the charge
continues to increase until this voltage equals the applied
voltage. The charge in a capacitor is related to the
capacitance and voltage as follows:
Q = CE,
in which Q is the charge in Coulombs, C the capacitance in
farads, and E the emf across the capacitor in volts.
(1) Charge Cycle. A voltage divider containing resistance and
capacitance is connected in a circuit by means of a switch, as
shown at the top of figure 34 on the following page. Such a
series arrangement is called an RC series circuit
In explaining the charge and discharge cycles of an RC series
circuit, the time interval from time tO (time zero, when the
switch is first closed) to
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