Holooly Plus Logo
Holooly Plus Logo

Question 19.SP.2: A RL series circuit has the following values: V = 75 V dc, R......

A RL series circuit has the following values: V = 75 V dc, R = 50 Ω, and L = 15 H. (a) Find the time constant. (b) How long after the circuit is energized will the current reach a steady value? (c) What is the steady-state value of current?

Step-by-Step
The 'Blue Check Mark' means that this solution was answered by an expert.
Learn more on how do we answer questions.
Report Answer

(a) Write the formula for the time constant, Eq. (19-12), and substitute given values.

t =T=\frac{L}{R}   (19-12)

T=\frac{L}{R}=\frac{15}{50}=0.3\ s

(b) A steady-state value of current is reached after five time constants.

5T = 5(0.3) = 1.5 s

(c) I=\frac{V}{R}=\frac{75}{50}=1.5\ A

Related Answered Questions

Question: 19.SP.9

A RC series circuit with a square-wave input is shown (Fig. 19-15). The input is a periodic train of pulses with an amplitude of 10 V and a width of 1 ms, with each pulse generated every 2 ms. Plot the output voltage curve across the resistor. ...

Verified Answer:

T=R C=\left(1 \times 10^3\right)\left(0.1 \...
Question: 19.SP.8

A RC series circuit with a rectangular pulse input is shown (Fig. 19-13). A rectangular pulse is a special case of a constant dc source because the voltage is a constant V when the pulse is on and a constant zero when the pulse is off. If a single pulse is applied to the circuit, find the voltage ...

Verified Answer:

Find the time constant of the circuit. T=R ...
Question: 19.SP.7

A simple switching circuit for producing a sawtooth wave is shown (Fig. 19-12a). The switch S is closed and then opened very quickly so that the capacitor is not fully charged but only charged to the linear portion of its charging exponential curve (Fig. 19-12b). (The linear portion is the ...

Verified Answer:

Write the voltage formula for charging the capacit...
Question: 19.SP.6

For the circuit shown (Fig. 19-11), a 40-μF capacitor is added across the 20-μF capacitor in the circuit of Fig. 19-10. Find the time constant of this circuit and the voltage across this circuit 3 s after the start of charge. ...

Verified Answer:

Find the total capacitance for two capacitors in p...
Question: 19.SP.5

For a RC series circuit (Fig. 19-10), find (a) the time constant of the circuit; (b) vC and vR one time constant after the switch is closed and at 5 s, and (c) vC and vR one time constant after discharge starts, assuming the capacitor is fully charged to 10 V. ...

Verified Answer:

(a) Write Eq. (19-23) for the time constant in a R...
Question: 19.SP.4

A RL circuit (Fig. 19-9) is used to generate a high voltage to light a neon bulb, which requires 90 V for ionization at which time it glows. When the circuit is open, the high resistance R2 produces a low time constant L/R so that the current drops toward zero much faster than the rise of current ...

Verified Answer:

(a) The time constant is the ratio of total induct...
Question: 19.SP.3

In the circuit shown (Fig. 19-8), find (a) the total inductance and (b) the time constant. Assume that a current of 10 A is flowing when the switch S is opened. Find (c) the current 2 s later. ...

Verified Answer:

(a) Reduce the series-parallel combination .of ind...
Question: 19.SP.1

A series circuit contains a resistance of 20 Ω and an inductance of 10 H connected across a voltage source of 110 V. (a) What is the current 1 s after the circuit is closed? (b) What are vR and vC at this time? Some time after the current reaches a steady value, the switch is opened. When the ...

Verified Answer:

(a) Step 1. Write the formula for charging or risi...
Question: 19.12

If a RC circuit has a time constant of 1 s, how long will it take for vR to drop from 100 to 50 V? ...

Verified Answer:

Write the time equation for voltage decay, Eq. (19...
Question: 19.11

One time constant for a series RC circuit is also defined as the time in seconds required for the capacitor to charge to 63.2 percent of its final value. Show that this statement is true. ...

Verified Answer:

Write the capacitance voltage equation v_{C...