c. In a similar way, all values of current can be determined

until the steadystate condition is reached. The voltages and

currents at the end of each usec, for the problem just discussed, are

shown in Table II. Check these values with those given for the same

period of time in Table I. The values obtained using the stepby

step procedure are slightly higher, but very close to the actual

values. The response of a series RL circuit to any type of input

voltage waveform can be determined by using these same time constant

and voltage equations.

Table II. Voltage and current values when positive step

voltage is applied to a series RL circuit

Section III. RC CIRCUIT RESPONSE AND VOLTAGE DROPS

9.

GENERAL.

In the following discussion, the voltage, current, rate of

charge, and rate of discharge of an RC circuit are examined at a

number of intervals during the transient period following the

application of positive and negative step voltages.

10.

TRANSIENT RESPONSES.

a. Positive step voltage. The curves in Figure 20 represent the

current and voltage waveforms of a series RC circuit. At the instant

that E is applied to the circuit, Ec is equal to zero, ER is equal to

E, and the current in the circuit is at maximum. At the end of 1

time constant (RC time constants are discussed in Section IV of this

chapter), the current (Curve B) has rapidly decreased to 36.8 percent

of its maximum value. ER (also Curve B) is directly proportional to

It and is, therefore, also equal to

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