Concept explainers
In the circuit of Fig. 7.117, find ix for t > 0. Let R1 = R2 = 1 kΩ, R3 = 2 kΩ, and C = 0.25 mF.
Figure 7.117
Calculate the current
Answer to Problem 50P
The current
Explanation of Solution
Given data:
Refer to Figure 7.117 in the textbook.
The source current
The value of resistances are
The value of capacitance
Formula used:
Write the general expression to find the complete voltage response for an RC circuit.
Here,
Write the expression to find the time constant for an RC circuit.
Here,
C is the capacitance of the capacitor.
Calculation:
The given Figure 7.117 is redrawn as shown in Figure 1.
For
The switch is kept open at this condition. Therefore, the initial capacitor voltage
For
In Figure 1, the current source
That is,
Figure 2 shows the modified circuit diagram when
In Figure 2, the final capacitor voltage
Figure 2 shows the Thevenin resistance
In Figure 3, the Thevenin resistance is calculated as follows.
Substitute
Substitute the units
Substitute
Figure 4 shows the modified circuit diagram to find the current
In Figure 4, apply Kirchhoff’s current law at node 1.
In Figure 4, apply Kirchhoff’s current law at node
Substitute
Reduce the equation as follows,
Substitute
Reduce the equation as follows,
Conclusion:
Thus, the current
Want to see more full solutions like this?
Chapter 7 Solutions
Package: Fundamentals Of Electric Circuits With 2 Semester Connect Access Card
- For the following circuit obtain: (a) the response v(t) for t>0, (b) the current i(t) through the inductor for t>0.arrow_forward11. 7.11 The switch in the circuit seen has been in position 1for a long time. At t=0, the switch moves instantaneously to position 2.Find the value of R so that 20% of the initial energy stored in the 30 mHinductor is dissipated in R in 15 μs.arrow_forward1. 7.1 The switch in the circuit shown has been closed for a long time andis opened at t=0.1. a) Calculate the initial value of i.arrow_forward
- The current (I) flowing in a circuit containing a capacitor that is discharging changes with time (t) according to the equation:I = Io e-t/(CR)A circuit contains a capacitor of 30 x 10-6 F in series with a resistance of 4.7 x 10 5 Ω. If the initial current is 3.5A , calculate the current after 15 s.arrow_forward7. 7.7 PSPICEMULTISIM The switch in the circuit has beenclosed for a long time. At t=0 it is opened.2. b) Write the expression for vo(t) for t≥0+.arrow_forwardIn the circuit below, the switch is closed at t=0 s. It is known that the voltage across the capacitor at t=0.2 s is Vc( t = 0.2 ) = 10.31 V. In this case, what will be the voltage Vc( t = 0.1 ) of the capacitor at t=0.1 s? Calculate.arrow_forward
- 5) Consider the circuit shown below, in which the switch opens at t=0. Find expressions for v(t), iR(t), and iL(t) for t>0. Assume that iL(t) is zero before the switch opens.arrow_forward2. 7.8 The switch in the circuit has been open for a long time. The initialcharge on the capacitor is zero. At t=0 the switch is closed. Find theexpression for 2. b)v(t) for t≥0+.arrow_forwardNo energy is stored in the 100 mH inductor or the 0.4μF capacitor when theswitch in the circuit shown is closed. Find vC(t) for t≥0arrow_forward
- 1. For the circuit in find the value of R that resultsin a critically damped voltage response.2. Calculate v(t) for t≥0.3. Plot v(t) versus t for 0≤t≤7 msarrow_forward19. 7.19 PSPICEMULTISIM The two switches shown in the circuit operate simultaneously. Prior to t=0 each switch has been in itsindicated position for a long time. At t=0 the two switches moveinstantaneously to their new positions. Find1. a) vo(t), t≥0+arrow_forwardAn LTI system has an impulse response: h(t) = e'u(t + 2) This system is: Select one: Causal but not stable Not causal but stable Not causal and not stable Causal and stablearrow_forward
- Introductory Circuit Analysis (13th Edition)Electrical EngineeringISBN:9780133923605Author:Robert L. BoylestadPublisher:PEARSONDelmar's Standard Textbook Of ElectricityElectrical EngineeringISBN:9781337900348Author:Stephen L. HermanPublisher:Cengage LearningProgrammable Logic ControllersElectrical EngineeringISBN:9780073373843Author:Frank D. PetruzellaPublisher:McGraw-Hill Education
- Fundamentals of Electric CircuitsElectrical EngineeringISBN:9780078028229Author:Charles K Alexander, Matthew SadikuPublisher:McGraw-Hill EducationElectric Circuits. (11th Edition)Electrical EngineeringISBN:9780134746968Author:James W. Nilsson, Susan RiedelPublisher:PEARSONEngineering ElectromagneticsElectrical EngineeringISBN:9780078028151Author:Hayt, William H. (william Hart), Jr, BUCK, John A.Publisher:Mcgraw-hill Education,