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. Planobilly

    What Are the Implications of Changing Component Values in a Tube Amp Circuit?

    Hi Guys, The schematic What do you think the effect of changing the value of the output tube cathode capacitor from 50uf to 250uf would be? Also the original schematic showed 500K pots and other newer schematics show 1M pots. What do you think the effect of that change would be? Next...
  2. diegovmtj

    Help with two electrical circuits please

    Hey, I am having problems with this. I need help with these 2 circuits I am basically lost and not sure how to start. I need to find voltage, current and potency on each resistance help would be much appreciated, thank you http://imgur.com/trm1On0 http://imgur.com/a/KD3zr
  3. sammyqw

    Engineering RC Circuit Problem: Hi, Is Capacitor Replaced by Short Circuit?

    Homework Statement 2. Homework Equations [/B] KCL, Node Analysis , Mesh Currents The Attempt at a Solution Hi, in part b when t>0 the capacitor is replaced by an open circuit , however in part c the capacitor is replaced by a short circuit why is that?Aren't inductors the only ones...
  4. sammyqw

    How Did They Calculate Vo in the Circled Step?

    Homework Statement http://imgur.com/ZKiCbbA http://imgur.com/a/ccGTV Could someone explain me what happened in the step that is circled in red please? I would appreciate it. did they multiply i0x(iL)? Homework Equations they got iL by using iL=iL(initial)*e^-t/Tau . How did they get Vo? what...
  5. D

    Engineering Circuit with multiple voltage sources

    Homework Statement a. Find the voltages Va, Vb, and Vc. b. Find the currents I1 and I2. Homework Equations Ohm's Law, Current Divider The Attempt at a Solution [/B] My first attempt was to redraw the circuit. I know that these voltages are with respect to ground. Therefore Va to Ground is...
  6. sammyqw

    Engineering Circuits 1 help with this circuit in a DC state

    Homework Statement http://imgur.com/a/4YfkJ http://imgur.com/a/4YfkJ Homework Equations for t<0 I understand that Capacitor acts as an open circuit and goes away but why did the 90v and 6ohm resistor disappeared? is it because current doesn't go that way? and also in that KCL at node V1...
  7. sammyqw

    Engineering Circuits 1 help with integration

    Homework Statement http://imgur.com/a/qlQ5z Homework Equations i=i(o)+1/L integration(v0) dt formula is in the attemp at a solution. The Attempt at a Solution http://imgur.com/a/HVjl1 For the interval 2<t<infinite . I understand...
  8. Cocoleia

    Simplifying a circuit w/ multiple resistors & current source

    Homework Statement I am given this circuit...
  9. sammyqw

    Engineering Can someone explain me what happen in this step? Circuits 1

    Homework Statement http://imgur.com/tQR7Jdt Homework Equations xc= vm/im The Attempt at a Solution http://imgur.com/a/RwIUA Can someone please explain where did they get that pi/2 ? did they integrate 2cos(10t)or something? Thanks
  10. whatphysics

    Engineering Solving Circuit Analysis Problem: Finding R and V(t) for Given Conditions

    There is a question I am not sure of how I should start/approach. Any help would be appreciated, thanks. Vc(0)=3V and ic(t)=e^-50t for t>0 and t=0. Find the value of R and voltage v(t) for t>0 and t=0
  11. F

    Estimating the upper 3dB cutoff in a MOSFET amplifier

    Homework Statement I've found the gain, but now I need to estimate the upper cutoff frequency with the open circuit time constant method, so the upper 3dB cutoff would roughly be $$\sum_{i = 1}^{n} \frac{1}{\tau_i}$$ The attempt at a solution I'm currently trying to make sense of the given...
  12. Cocoleia

    Use Kirchoff's laws to solve for tension and current

    Homework Statement http://postimg.org/image/ys43ylstp/ [/B] I need to find tension and current in each element of the circuit. I have included an image of what I have drawn so far for the circuit. http://postimg.org/image/ys43ylstp/ Homework Equations Kirchoff's laws. The Attempt at a Solution...
  13. E

    Engineering Validity of interconnection in electric circuit

    Homework Statement Homework Equations P=Vi The Attempt at a Solution For part a, it looks like the dependent current source (4i1) leads directly to i1, with nothing that could change it. This would mean the interconnection is invalid, right? I can't tell if this circuit is in series or in...
  14. BiGyElLoWhAt

    Optimization Problem with an RC BP filter

    I am assigned to design a circuit that peaks voltage at 10kHz and is less than half peak voltage at 3k and 30k. Only capacitors and resistors are allowed. The circuit I'm using is attached. I end up with ##I_0 = [\frac{-R_2\omega^2C_1C_2 + [C_1+C_2]R_1R_2\omega^3C_1C_2 - R_1\omega^2[C_1+C_2]^2...
  15. RoboNerd

    Question on lightbulb brightness in circuit analysis

    Homework Statement Homework Equations I know that power of a lightbulb/resister is I^2 * R The Attempt at a Solution OK. Here's my attempt: Let's consider the situation where we do not close the lightbulb and assume that the wires and switch are ideal because they have no resistance. I...
  16. R

    Hard Circuit simplification problem

    Homework Statement Everything is in the picture. Question 3(a) This is for preparation for a contest. http://i.imgur.com/FtiKaYw.jpg Homework Equations V=IR The Attempt at a Solution I calculated the total resistance of the first circuit and used that to evaluate V(AB). But this is in...
  17. Kfir Dolev

    I Is it possible to build a phase shifter from RLC components?

    Say you have a circuit component with impedence Z(\omega). Is it possible combine it in some way to resistors, capacitors, and inductors, so as to shift the phase of the impedance by a constant?
  18. Kfir Dolev

    Combine capacitors and inductors to be frequency independent

    Is it possible to combine (possibly infinite) capacitors and inductors to get a total impedance which is independent of frequency. If so, how?
  19. E

    Power Resistor Immersed In Water

    Homework Statement For the circuit shown below the 20-ohm resistor is immersed in water surrounded by insulating foam; the equivalent resistance through the circuit is 40 ohms. The current through it is 0.75A. What is the power dissipated through the 20 ohm resistor? Homework Equations $$...
  20. O

    Why does a voltmeter measure a voltage across inductor?

    The potential difference across an inductor is supposed to be zero, but a voltmeter measures it to be L*dI/dt. Also, if the p.d is zero then the electric field in the wires of the coil will be zero and in that case, why should charges flow at all? What am I missing?
  21. K

    Optimizing Circuit Design: Voltage Range, Internal Resistance, and Wire Sizing

    Hi all. In a project I'm working on I'm needing to model a DC circuit to find the required power sources/storage to keep the system voltages up to a sufficient level. There's a solar cell array, a reversible fuel cell stack, various DC "appliance" loads, and wire runs with resistances. I dug...
  22. G

    Engineering Circuit analysis -- Find the complex apparent power of I(g2)

    Homework Statement Given the circuit of sinusoidal current (attachment 1) with given data: \underline{Z_3}=200(3-j4)\Omega, \underline{Z_4}=100(3+j20)\Omega, \underline{Z_5}=100(3+j4)\Omega, \underline{Z}=100(2+j5)\Omega, \underline{I_{g2}}=-10(2-j)mA After the switch is closed, the increment...
  23. G

    Engineering Circuit analysis -- Find active and reactive power in the branch....

    Homework Statement Given the circuit of sinusoidal current (attachment 1) with given data: \underline{E}=100V,\underline{E_1}=40V,\underline{Z}=(10+j10)\Omega,\omega=10^5rad/s,L=1mH, C=0.1uF. Find \underline{I_L},\underline{U_{16}}, active and reactive power in the branch 2-5. 2. The...
  24. I

    "AC Circuit Analysis - Find i1(t) & i2(t)

    Homework Statement Find the currents through ##R_3, i_1(t)## and ##R_2, i_2(t)##. I attached a diagram of the circuit (diagram.pdf). In the original diagram the currents I'm trying to find is marked going top to bottom, there's also no directions on the voltages in the original diagram but...
  25. Swapnil Das

    Method of Symmetry for Equivalent Resistances

    I have been studying the method of symmetry from some days, which essentially reduce the effort needed for the evaluation of equivalent resistances. My textbook states: Points having symmetrically located about initial and final points have the same potentials.So, the resistances between these...
  26. Titan97

    Capacitor and inductor in parallel

    Homework Statement [/B] Find the power supplied by the battery. Homework Equations $$Z_C=-iX_C$$ $$Z_L=iX_L$$ The Attempt at a Solution $$Z_1=R_1-iX_C=\sqrt{R_1^2+X_C^2}e^{i\phi_1}$$ $$Z_2=R_+iX_L=\sqrt{R_2^2+X_L^2}e^{i\phi_2}$$ $$I_1(t)=\frac{V_0}{\sqrt{R_1^2+X_C^2}}e^{i(\omega...
  27. loki4000

    Quick question about transformer circuit

    Homework Statement Can someone inform me wheher my solution is correct? Homework Equations V1 = E2 * (10^-3)/2*(10^-3) = 0.001 V2 = E1 Ra = (R2+R3) = 0.02 Rb = R1 = 30 n = (1/100) n^2 = (1/100)^2 The Attempt at a Solution I1 = (V'1 - V2)/(Ra'+Rb) I1 = (0.001/n - 230)/(0.02/n^2 + 30)...
  28. Titan97

    B RLC Circuit Analysis: Phase Difference & Impedance Modulus

    In an RLC series circuit let applied EMF be given ##V=V_0\sin\omega t##, $$Z=Z_C+Z_R+Z_L=R+i\left(\frac{1}{\omega C}-\omega L\right)$$ $$|Z|=\sqrt{R^2+\left(\frac{1}{\omega C}-\omega L\right)^2}$$ Then $$i(t)=\frac{V(t)}{Z}=\frac{V_0e^{i\omega t}}{R+i\left(\frac{1}{\omega C}-\omega L\right)}$$...
  29. Matt atkinson

    State Space Model for a Circuit R, L, C

    I have been struggling to solve the following problem for days. I was given the state space model of a circuit and asked to determine the system elements. So basically, I think I have to find a suitable circuit which describes the state space equation. I am not really sure how to approach this...
  30. kamhogo

    Find currents and voltages - 2 batteries & 3 resistors

    Homework Statement Find I1, I2, I3 as well as the voltages across each resistor. R1= 50 ohms R2= 220 ohms R3= 150 ohms Homework Equations Kirchhoff's loop law Kirchhoff's junction lawThe Attempt at a Solution Loop 1: Starting from the negative terminal of the 10V battery (ccw) 10V - 50...
  31. F

    Calculating R and C values given input and output voltage

    Homework Statement Homework Equations $$ V=IR $$ The Attempt at a Solution To simplify the algebra it was suggested that I set $$ R_{1}=R_{2}=R $$ and $$C_{1}=C_{2}=C $$ So that's what I did. I labeled the voltage in the middle node as $$ V_{1} $$Taking KCL at the middle node gives $$...
  32. S

    Engineering Solving for i and v_x: A Homework Challenge

    Homework Statement Find i and v_x Given answer: 2. Homework Equations 3. The Attempt at a Solution I have attempted the problem in two different manners, and I consistently reach a different answer. I would appreciate if someone would be willing to take the time to attempt the problem and...
  33. kamhogo

    Find I through one of three resistors in a 3-battery circuit

    Homework Statement [/B] Sorry for the quality of the image. This is the best I can come up with with my cellphone. What is the current through the 10 ohms resistor? Is the current from left to right or right to left? Homework Equations Kirchhoff's loop law Kirchhoff's junction law The...
  34. G

    Thevenin's circuit analysis. Multiple voltage sources

    Hi, i am halfway through one of my assignments and i require some assistance. I do not seek the answer to the assignment just a little boost to my knowledge. 1. Homework Statement Basically, if i am calculating the Thevenin's voltage and the resistor i have removed that is in question has a...
  35. M

    Finding Thevenin Equivalent with Dependent Source

    Homework Statement I am trying to find the Thevenin Equivalent of this circuit Homework Equations Using KCL and node voltage The Attempt at a Solution I found the open circuit voltage for the thevenin voltage so far by the mesh current method, and now I am trying to find the closed circuit...
  36. V

    Find voltage across resistor using mesh current analysis

    I'd like to find Vth by mesh current analysis. Mesh A and B share a current source, so they're treated as one supermesh. What's the equation for this supermesh? Also, do I ignore the loop with the open circuit? Since there's no current flowing there... 2A = ib - ia Anyway, is this the right...
  37. F

    Engineering Circuit Analysis-Converting a square wave to a sine wave

    Homework Statement For an upcoming lab I've been asked to build a circuit to convert a square wave (vi(t))e into a sine wave (v0(t)) by selecting appropriate resistor/capacitor values for the circuit below (from what I know, it's impossible to produce an accurate sine wave with just this, I...
  38. Titan97

    Classical Book for learning AC circuit analysis

    I haven't used any book for AC circuit analysis yet. I have learned the basics of phasor diagrams which my teacher taught in the class (We were only taught series combination of LCR circuits). Can anyone suggest a book to learn more about circuit analysis (like source transformations, Norton's...
  39. chrispypatt

    Final Value Theorem Rule Clarification

    My homework problem is as follows: Consider the Laplace transform shown below. (4s3+15s2+s+30)/(s2+5s+6) a. What is the value of f(t=0) and f(t=∞)? Use the initial and final value theorems. b. Find the inverse transform f(t). Use this expression to find f(t=0) and f(t=∞) and compare with the...
  40. S

    Understanding Potential Dividers in Circuit Analysis

    Homework Statement how did they get this ?? it is like a potential divider, can anyone explain... Homework EquationsThe Attempt at a Solution this is what i got[/B]
  41. D

    How to analyze a complex circuit

    Homework Statement Homework Equations Kirchoff's Current and Voltage laws The Attempt at a Solution How do you go about analyzing a complex circuit like this? Do you just write out the current equation for each highlighted junction and voltage equations for each loop? Is there a quick way...
  42. A

    Finding potential difference between two points in a ladder circuit

    Homework Statement Find the potential difference ##V_A– V_B## for the circuit shown in the figure. Homework Equations Kirchhoff's laws. The Attempt at a Solution If we assign potentials to junctions starting by setting ##A=0## Current ##i_1## flow through each vertical resistances and ##i_2...
  43. A

    Find the resistance of a resistor using Ohm's Law?

    Hi, I have been at this problem for days and I can't seem to see what I am doing wrong. Here is the circuit layout along with my work As you can see I am running into problem getting values of current that do not add up equal to zero. My professor has never discussed how adding a wire like...
  44. F

    Engineering Solving an RL Circuit Analysis Problem

    Hello! It's a pretty long time time since I did my last circuit analisys, so I feel a bit rusty. I have to calculate the evolution of current in the inductor: L is generic and u(t) is the Heaviside step function. Do note that at t = 0 the inductor behaves like a short circuit (I don't know...
  45. O

    Is my lecturer incorrect or did I just misunderstand? (sound quality)

    I'm a first year electrical engineering student and I had a lecture on Analogue and power electronics today. The main topic the lecturer was talking about was headphones and stereo systems etc. We learned about frequency responses and looked at product specifications and circuit analysis and...
  46. **Mariam**

    2 capacitors reaching equillibrium?

    Homework Statement A capacitor 1 of 3nF is charged with 3 volts. When it is completely charged, we connect it to an uncharged capacitor 2 of 7 nF. Calculate the charge on each capacitor after they reach electric equillibrium. Homework Equations Q=CV The Attempt at a Solution my confusion is...
  47. Titan97

    Phasor algebra in AC circuit analysis

    Homework Statement Find the peak value of current through the AC source of the following L-C-R circuit, if peak voltage is ##V_0## and angular frequency is ##\omega_0##. Homework Equations I have learned Vector algebra and calculus (single variable). I was taught how to use phasor diagrams...
  48. InsaneScientist

    Engineering Approach for solving voltage across a resistor in circuit?

    Homework Statement I must solve for the voltage across the resistor labelled R1 in the circuit above. The values given are the resistance of each resistor, the voltage of each voltage source and the current of the current source. Note: If referring to circuit loops consider them as being...
  49. MacLaddy

    Engineering Phasor Circuit Analysis Homework: Understanding Incorrect Answers | MacLaddy

    Homework Statement Hello folks. I had a recent midterm where I got a problem wrong, but I'm not sure I understand why. I am hoping someone here can shed some light. Please see the attached circuit diagram.Homework Equations Phasor notation stuff... I am correct on all except one sign. Please...
  50. Gbox

    Find Current I: 2 R & V Short Circuit

    Homework Statement All resistors have resistance of R and all voltage sources have voltage of V, Find the current I Homework EquationsThe Attempt at a Solution At the leftmost corner I can connect the two resistors in parallel, but what should I do with the short on the top right?
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