Discharge Cycle.

Electronic Principles
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54

voltage. This is shown by comparing figure 34, graph A to graph

D, on the previous page. In graph A, the voltage changed

instantly from 0 volts to 6 volts across the circuit., while the

voltage developed across the capacitor in figure 34, graph D

took the entire time interval from to to time t1 to reach 6

volts. The reason for this is that In the first instant at time

to, maximum current flows through R and the entire circuit

voltage is dropped across the resistor. The voltage impressed

across the capacitor at to is zero volts. As time progresses

toward t1, the decreasing current causes progressively less

voltage to be dropped across the capacitor (C). At time t1, the

voltage across the capacitor is equal to the source voltage (6

volts), and the voltage dropped across the resistor (R) is equal

to zero. This is the complete charge cycle of the capacitor.

As may have been noticed, the processes which take place in the

time interval to to t1 in a series RC circuit are exactly

opposite to those in a series LR circuit.

For comparison, the important points of the charge cycle of RC

and LR series circuits are summarized in table 1 on the

following page.

(2) Discharge Cycle. In figure 35 on page 56, at time to, the

capacitor is fully charged. When S1 is open and S2 closes, the

capacitor discharge cycle starts. At the first instant, circuit

voltage attempts to go from source potential (6 volts) to zero

volts, as shown in figure 35, graph A. Remember, though, the

capacitor during the charge cycle has stored energy in an

electrostatic field.