Circuit analysis Definition and 569 Threads

A network, in the context of electrical engineering and electronics, is a collection of interconnected components. Network analysis is the process of finding the voltages across, and the currents through, all network components. There are many techniques for calculating these values. However, for the most part, the techniques assume linear components.
Except where stated, the methods described in this article are applicable only to linear network analysis.

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  1. M

    Engineering Transient circuit analysis problem with a dependent source

    Hi all, I tried to solve this, but I can't find the R(equal). I use the following method. The circuit: For t<0 the switch is closed so the iL(0-)=4 A For t>0 it opens and the iL(∞)=0 A Now, I want to find the value τ=L/R(equal) Then I will use the: iL(t) = iL(∞) + ( iL(0-) - iL(∞) )* (...
  2. M

    Calculating Vo in an AC Circuit Using Superposition Theorem

    This is the circuit: I try with KVL: But the given answer is 6.66L33.67 Volts. So, I'm confused, any suggestions ?
  3. E

    Solve Vo: Voltage Nodal Analysis w/ KCL Equation

    I'm asked to solve for Vo for this equation. I've set the bottom node to be my reference node before applying nodal analysis. When included in the KCL equation for node at Vb, will the dependent voltage source 20iΔ be negative since the current through that element is leaving node C? Say, the...
  4. L

    Circuit analysis: Six resistors and two batteries

    Problem Statement: ) A circuit is constructed with six resistors and two ideal batteries as shown. The battery emfs are ε1 = 18 V and ε2 = 12 V. The values for the resistors are: R1 = R5 = 55 Ω, R2 = R6 = 110 Ω, R3 = 44 Ω, and R4 = 117 Ω. The chosen positive directions for the currents are...
  5. e0ne199

    Engineering Problem about steady-state circuit analysis

    Here is the question, and my solution is for question (a) : knowns : I = 12 cos 2000t = 12 ∠0° L=0.2 H R=200Ω ω=2000, XL = j*0.2*2000 = j400Ω Zt = (j400*200)/(200+j400) = 178.9 ∠26.57°Ω i want to find the power absorbed by R, so : IR = (Zt /R)*I = (178.9 ∠26.57°Ω/200)*12 ∠0° = 10.73∠26.57°A...
  6. M

    2-Resistor, 2-Capacitor Circuit with Switch

    I already did part a and got the correct answer of 4.8 microC. However, I am unsure how to approach part b, where the switch is closed and apparently the two capacitors end up with different charges. For part b, since there is a path between the two capacitors, I don't know if I am able to...
  7. IonizingJai

    Nodal Analysis Problem help (Double Supermesh)

    That is, for Supernode -1,3 (12V branch) , we do Nodal Analysis and we have (V2-V3)/2 , over the 2 ohm branch. But this current is not included in the Equation 1 in the solution I have attached(Which is my only source to cross check answers/solution right now.) Is the solution wrong? Thanks...
  8. preet_jay

    Circuit Analysis Question -- Solving for a multi-resistor circuit

    From what I understand is that you can sum up R3 and R4 to get 350 ohms Then you can can a parallel circuit with the missing resistors, 4amp and the new 350 ohm resistor and that's about it. My textbook says the answer is 55 ohms for the resistors and the current is 0.073 but I got 3.75 ohms...
  9. DeclanKerr

    RLC Circuit Analysis with system of ODEs

    Summary: Looking for guidance on how to model an RLC circuit with a system of ODES, where the variables are the resistor and inductor voltages. This is a maths problem I have to complete for homework. The problem is trying to prove that the attached circuit diagram can be modeled using the...
  10. christang_1023

    LR Circuit Analysis: Solving Equations w/ Kirchhoff's Rule

    Above is the figure of the question. According to Kirchhoff's Rule, I have obtained three equations $$\varepsilon-iR_{10}-L_{40}\frac{di_1}{dt}=0$$ $$L_{40}\frac{di_1}{dt}-i_2R_{60}=0$$ $$i_2R_{60}-R_{30}(i-i_1-i_2)-L_{15}\frac{d(i-i_1-i_2)}{dt}=0,$$ where ##\varepsilon## stands for emf=100V...
  11. M

    Charged Capacitor Connected to an Uncharged Capacitor in Series

    I have already solved up to after the switches are flipped, and all the charge is on C1. See the second attached image for a detailed diagram of the situation after the switches are flipped. However, the notes then say that all the charge is trapped between C1 and C2, which I don't understand...
  12. Electgineer

    Is there a better way to assign current direction in circuit analysis?

    Is there like a rule of thumb, or a simple hack for assigning current direction in circuit analysis? Even when I m consistent with the direction I choose, I still get the wrong answer most of the time. Like 1. Do current source or voltage source affect when choosing current direction? 2...
  13. Zeynaz

    LDR circuit electricity question

    So far what i figured out is that R2 and R3 are in parallel, R1 and LDR in parallel. And these two parallel circuits are parallel to each other ( tell me if I am wrong) The voltmeter has to read 0 but I am not sure how i can achieve that. Is there a rule where when the resistance of each side...
  14. fight_club_alum

    Kirchoff's law and circuit analysis

    I assumed the current flows from the 20V so, 20V - 100 (i1) - Ri2 = 0 First loop 20V = 100i1 + Ri2 Second loop +Ri2 + 40V - 200(0.08) = 0 Ri2 = -24 Back to equation 1 20 v = 100i1 + (-24) therefore, i 1 = 0.44 For loop two: i1 - i2 = i3 0.44 - i2 = 0.08 therefore i2 = 0.36 ohms...
  15. D

    Engineering Question on basic circuit analysis

    My initial attempt had me combining the 40 and 20 ohm resistors in series, then combining the result with the 120 ohm resistor in parallel (top). However, this was incorrect. According to my answering guide, the correct method was to transform the voltage source into a current source, then...
  16. F

    Engineering Help me finding the current in here please (Circuit analysis)

    Hi! I've been struggling with this. Original exercise here: Find the value of Iy when R=0. And the value of Vx when R is infinite. For the first part of the question I did this since R=0: I've tried to solve this circuit and I get that Iy and I5 are 0 A, and this can't be possible since Iy...
  17. Zack K

    Mesh Analysis Method for Finding Current in a Circuit with Dependent Source

    Homework Statement Find the current in each resistor. (refer to uploaded diagram) Homework Equations ##Kirchhoff's Law: I_s=I_1 + I_2## Mesh analysis method The Attempt at a Solution I'm calling ##I_s## the total current before and after the current splitting up, and ##I_1## and ##I_2## are...
  18. J

    Finding the Current in a circuit

    Homework Statement The diagram below shows a circuit where; R1 = 5.0 Ω, R2 = 8.0 Ω, R3 = 1.0 Ω, V1 = 16.8 Volts, V2 = 1.5 Volts, and V3 = 39.6 Volts. What is the value of I1? In solving this problem, initially pick the current directions as shown. If the actual current turns out to be in the...
  19. A

    Engineering Find the time constant for this RC circuit, help please

    Homework Statement Homework EquationsThe Attempt at a Solution
  20. e0ne199

    Engineering Problems about Zin in complex circuit analysis

    1. Homework Statement the problem is my answer for question (a) is not the same as the answer provided by the question, i get 2.81 - j4.49 Ω while the answer demands 2.81 + j4.49 Ω Homework Equations simplifying the circuit, details can be seen below The Attempt at a Solution...
  21. O

    Comparing the brightness of each bulb in a circuit

    Homework Statement Four identical light bulbs are connected to a battery as shown in the diagram. Switch S is originally closed. If switch S is opened, what happens to the brightness of each bulb? Homework Equations V=IR The Attempt at a Solution - By opening the switch, no more current...
  22. Muhammad Usman

    How Do You Handle KVL Limitations in High-Frequency AC Circuits?

    Hi, I was reading KVL and KCL and I read that KVL cannot be applicable to all the situations specially when :- " KVL is applicable on the assumption that there is no fluctuating magnetic field linking the closed loop. While, in presence of changing magnetic field in a High Frequency but short...
  23. C

    Symmetry in Electrical Circuit Analysis

    How is symmetry used to solve electrical circuits? I have seen several problems in books in which currents in two resistors are said to be equal due to 'symmetry'. That is a concept that I fail to understand and thus cannot apply. In class, we were shown a few circuit diagrams which were...
  24. Safder Aree

    Engineering Finding Internal Resistance through Circuit Analysis

    Homework Statement Given this following circuit: What is the internal resistance of the meter movement ( R_I). This is part of a project I'm doing and I know the equation that gives you the internal resistance in this circuit. $$R_I = \frac{R_sR_p}{R_s - R_p}$$. However, I have no idea how...
  25. archaic

    Current Through R1 and R3: Explained

    Hey guys, in the picture below, the current flowing through R1 is the same flowing through R3 right? And hence we have R1 and R3 in series? In this second picture R2 is going to cancel out because apparently that's what happens when you have a branch containing components parallel with a wire...
  26. E

    Voltage drop in the internal resistance of a voltage source

    In this circuit,first there will be voltage drop in the internal resistance of the voltage source.Mostly,the voltage source is assumed ideal in circuits,however,here a practical voltage source is assumed. So,there will be voltage drop in the internal resistance of the voltage source which will...
  27. AchillesWrathfulLove

    Engineering Do electrical engineers actually use Circuit Analysis skills?

    Do electrical engineers actually use stuff that is taught in Circuit Analysis classes like Node Voltage Method, Mesh Current Method, Kirchhoff Voltage/Current Law, Source Transformation. All these usually only involve resistors. Are they somewhat altered in a way to analyze circuits with other...
  28. AchillesWrathfulLove

    Which is a better method for Circuit Analysis?

    Node Voltage Method or Mesh Current Method.
  29. Curiosity 1

    Engineering Three-phase circuit: Why Z_Ye is parallel with Z_Δ?

    Homework Statement This problem is taken from Fundamentals of Electric Circuits (chapter 12, problem 15). Homework Equations As shown in the first blue box, I have trouble seeing why after the conversion, Z_Ye will be parallel with Z_Y. I think it's because the voltages 'emitting' from the...
  30. D

    Engineering Applying Kirchoff's Voltage Law to a circuit

    Homework Statement Using Kirchhoff’s rules, (a) find the current in each resistor shown in Figure P28.31 and (b) find the potential difference between points c and f.[/B]Homework Equations [/B] Σ ΔV = 0 (KVL) The Attempt at a Solution [/B] I have been trying to set up a system of equations...
  31. A

    Engineering Confusing circuit analysis question

    Hi I have the following situation: (Please see attached pic) I want to know if equation (4) i have written is correct. What is confusing me is that, I remember being told in circuit analysis that each energy storage element should have its own state variable. But in this situation when I...
  32. D

    Problem finding the output voltage using Laplace transform

    Homework Statement The input signal of the circuit shown below is ##x(t)=2\sin (ω_ot + \pi/6)##. The switch in the circuit is controlled with a digital signal of the form ##s(t)=\sum_{k=-\infty}^{+\infty} (u(t+ε-kT_s) - u(t-ε-kT_s))##, ##\frac{2\pi}{T_s}=800\pi##, ##ε\to 0##, so that when the...
  33. marsupial

    Engineering The effect of a switch in a Laplace circuit analysis

    Homework Statement The switch in the circuit in has been closed for a long time. At the switch is opened. a) Find i0 for t>=0 (b) find v0 for t>=0 I don't understand the effect of the switch in the position it is in. It's acting as a short circuit, I think, so presumably the capacitor doesn't...
  34. F

    Engineering Unknown resistor in a series-parallel circuit

    Hey guys, I have tried and tried to find a start to this problem with no success. My book may have the answer but unfortunately I must be not realizing it. So hopefully I just need a different perspective. Typically I would find the equivalent resistance of the circuit and then begin to...
  35. kstorm19

    Solving a circuit using both the mesh and node analysis

    Homework Statement The problem asks to solve for i1, i2, and i3 using the mesh method in the following circuit: I will also include the link, because I noticed I am having trouble attaching the image to the post: https://imgur.com/a/bBvuLXM I would also like to confirm the answer by solving...
  36. D

    Materials for DTL, TTL circuit analysis

    Hi fellow forum-ers :), I have a test in about two weeks where i am going to be given a dtl or ttl circuit which i have to analyse and calculate its function. The professor said that the circuit given to us will always be a useful and existing one meaning he's going to give us some NAND, NOR or...
  37. OldWorldBlues

    Why Use Voltage Dividers Instead of a Single Resistor?

    Hi! I'm working on a project in which a small microcontroller with a max. analog input of 5v takes readings from multiple sensors. I would like to make this input window a bit more versatile, and turned to voltage dividers as a solution. 'Problem is, I'm having a bit of trouble understanding how...
  38. paulmdrdo

    Engineering Op-Amp Circuit Analysis: Troubleshooting Incorrect Node Usage

    In the problem below, when I use nodes V1 and V2 I get the correct answer of Vo = -2.5v But when I use nodes V1 and Vo I get an incorrect answer. Please explain to me why my latter method did not work. Thanks.
  39. Valour549

    AC Circuit Analysis- Find Impedance

    Homework Statement 2. The attempt at a solution Am I doing something wrong? I know it's just voltage division with AC phasors and we have to equate the real parts and imaginary parts to find the unknown, but I feel like the question shouldn't be this hard.
  40. H

    Find the Voltage in the parallel resistor-capacitor circuit

    Homework Statement C1 = 4 micro F C2 = 8 mF R1 = 4 ohm R2 = 8 ohm V = 12 Questions : 1) Find current I when S not closed 2) find Vb, when Vc is 0 3) find Vd, when Vc is 0 4) total charge move from B to D Homework Equations Vf - Vi = F.d/q (not sure this below is useful equations) I = E/Z E...
  41. A

    Engineering Understanding Clamper Circuits: Analysis, Voltage Shifts, and Capacitor Behavior

    Hello everyone, I hope you could help me with the analysis of this circuit. the output voltage is supposed to be similar to the input but shifted upwards by 20V, so basically it's between 0 and 40V... but why? I mean when the input is 20V, the diode is reverse biased... and the capacitor...
  42. Bloopy

    MATLAB: Verification of Superposition Principle

    Homework Statement Verify Superposition Principle using Matlab, given a DC source of 100V, an AC source of 50V, 60Hz and three resistances, R1=10 ohms, R2=20 ohms and R3=15 ohms. I created the circuit below and ran the program. Result: Homework Equations None, just running the program...
  43. B

    [Homework] Identify Filter type

    Homework Statement Identify the type of filter (kinds of frequencies the circuit filters out) analytically 2. The attempt at a solution I believe the top filter to be an inverting low-pass filter, which passes lower frequencies and blocks higher frequency signals. I also think that the...
  44. H

    Calculating Resistance - Electrical Circuits & Networks

    Hello! I've took a course about Electrical circuits and Networks at the university, and i found out a problem which is uploaded by my professor, and i think he made a mistake! this is the solution i think that the equivalent resistances are wrong (beside Rab), for example if you look at...
  45. E

    Engineering Basic circuit problem -- Resistor network and a voltage source

    Homework Statement http://www.chegg.com/homework-help/questions-and-answers/problem-2-variableh-resistor-r-circuit-fig-p224-adjusted-va-equals-60-v-find-value-r-q8083343 Homework EquationsThe Attempt at a Solution Hi, I attached a pdf file with the problem. My question is, for the lower right...
  46. G

    What does this voltmeter measure?

    Homework Statement Consider the following circuit where i(t) is sinusoidal and exists across both components. (1) is an inductor and (2) is a capacitor. The ideal voltmeters measure effective value. What is the value measured by V2: [![enter image description here][1]][1] [1]...
  47. E

    I with this circuit -- 2 resistors and 2 sources....

    Homework Statement The problem is in this link https://www.chegg.com/homework-help/find-vo-io-circuit-fig-226figure-226-chapter-2-problem-7pp-solution-9780078028229-exc Homework Equations 3. The Attempt at a Solution [/B] 15=[io/3]+[io/3]+ [vo/12] I got this equation for the problem...
  48. H

    What's the current from this circuit? Is it a short circuit or not?

    Homework Statement Pic A, what's the I2? Pic B, what's the current across a-b ? Homework Equations V = I*R Voltage in series is different, the current is the same Current in parallel is different, the voltage is the same The Attempt at a Solution from Pic A, I found that I1 = 1A, I3 = 1A...
  49. Z

    How to know when to use Voc/Isc or Vtest/Itest for Thevenin?

    should you only apply the test sources when there are only independant sources in the circuit. Also would it be valid to zero all dependant source so that you are only left with independant sources and then apply the test source. It seems like i am always applying open and short circuit...
  50. Z

    Magnitude of the transfer function

    Hi all, In one of my problems there is a question with a plot of the transfer function magnitude versus frequency. In the graph I notice that the magnitude of the transfer function is greater than 1. This is confusing as I thought that filters are not able to increase the magnitude of the output...
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