through the resistor on its way to the capacitor. At time to,

the current flowing to the capacitor is maximum. Thus, the

voltage drop across the capacitor is maximum (E=IR). As time

progresses toward time t1, the current flowing to the capacitor

steadily decreases and causes the voltage developed across the

resistor (R) to steadily decrease. When time t1 is reached,

current flowing to the capacitor is stopped, and the voltage

developed across the resistor has decreased to zero.

It should be remembered that capacitance opposes a change in

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

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.

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.

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