Circuit theory Definition and 50 Threads

The current of the circuit would be: $$I=\dfrac{\varepsilon - \varepsilon'}{r+r'}=\dfrac{100-\varepsilon'}{1+r'}$$ But I do not understand the two methods of operation of the engine that the statement talks about: it rotates in normal regime and the engine is prevented from turning. What...

TL;DR Summary: How to find Time domain equation for RC circuit with AC input from inverse laplace transform For a simple RC circuit with AC input such as this: https://www.electronics-tutorials.ws/wp-content/uploads/2013/08/rc12.gif?fit=310%2C151?fit=310,226. If the AC input is just a simple...

For a simple bipolar transistor above, base-to-collector voltage gain ≈ -gm*Rc/(1+gm*Re) < 0, base-to-emitter voltage gain ≈ 1 > 0, should emitter-to-collector voltage gain ≈ -gm*Rc/(1+gm*Re) * 1 < 0. How come it is equal to gm*Rc > 0?

Hi all, I attached my attempt at a solution in the attached picture. I am using the textbook titiled as ”electronic circuit analysis“ by David E. Johnson, and op amp is in chap 3; while I did not find any example that attach the Vee and Vcc with amplifier . It seems that v+ = v- doesn’t hold in...

Hi, as follow-up to this thread I've a question about general representation of a two-port network. Basically it is ad hoc built four-terminal linear network (using controlled sources + nullator-norator pair): for it I found a general representation ##AV + BI = 0## as in the picture above. If...

Hello, I'm struggling with the conditions under which makes sense employ a two-port 'external' representation of a quadripole (four-terminal electrical network) when interconnected to an external circuit (to take it simple assume a linear + permanent electrical network). Starting from circuit...

This is not my homework. I took it upon myself to answer a textbook question for mental stimulation. I wanted to know if someone can verify if these were the correct values that needed to be solved for, process, and final answer, and if not, what needed to be considered. For the initial...

Hi, I'm reading the following paper (L. Chua) about the state-of-art of dynamic non linear circuit analysis -- Chua_Dynamic_Circuits I've a doubt about Theorem 2 on section 3.2 On the Existence of the Resistor Function that establishes sufficient conditions for the existence of network...

Hi, I'm aware it is an odd question. Consider a ##k##-terminal electrical device as black-box. We know from KLC and KLV that just ##k-1## currents and ##k-1## voltages are actually independent (descriptive currents and voltages). Furthermore we generally expect there exist ##k-1## relations...

Hi, I've a doubt about the applicability of the substitution theorem in circuit theory. Consider the following picture (sorry for the Italian inside it :frown: ) As far I can understand the substitution theorem can be applied to a given one-port element attached to a port (a port consists of...

Hi all, I'd appreciate help in calculating the voltages in the circuit shown. I thought it should be fairly straight forward, but it has me stumped. This is a sample-and-hold circuit for an ADC -- the switch is closed to charge the hold capacitor with the sample voltage and then opened to...

Greg Bernhardt submitted a new PF Insights post A New Interpretation of Dr. Walter Lewin's Paradox Continue reading the Original PF Insights Post.

Hello, I am currently taking a circuits class and I was looking for the solutions manual for the book Basic Circuit Theory by Charles Desoer. I haven't been able to find it anywhere but I really want it to practice more of the problems. I am able to do some but I never know if they are right or...

Homework Statement Given the known quantities ##R, C, L##, ##k##, and the effective values of the voltages ##E_1=E_2=E_3=E## , ##w = \frac{1}{\sqrt{LC}}## of the direct-symmetrical 3-Phase system find the expressions for the effective values of ##U_{12}##, ##U## and ##I## and calculate the...

I am retired from a major railroad co. where I worked on electronic weighing equipment. I have an associate of applied science degree from a local university. I have a basic understanding of dc and ac electricity but the explanation I recently read on this forum was the easiest to understand...

Homework Statement 1. V for C1 2. Let's Say "C" is Resistor then C1 = R1 etc. how to get Eq Resistance for this Circuit ?[/B]Homework Equations Faraday's Law, Kirchoff Law The Attempt at a Solution [/B] for no 1 :I just want to make sure. point A is transfering negative charge to C2 and...

Suppose I have some sort of a filter, whose transfer function is given by H(w), where w is the angular frequency of the input signal in radians per second. I want to know the maximum value of the transfer function. If I solve for the resonant frequency w0, which from my understanding is the...

Homework Statement http://imgur.com/qBXvrGz Above is a sketch of the circuit, a two stage symmetrical attenuator consisting of two symmetrical T attenuator pads connected in cascade, with the values that I have worked out for the resistors. The reduction is 15dB in the first stage, and 8dB in...

Homework Statement A step voltage of 120v is applied to a series CR circuit. R = 20KΩ, C = 4µF 1. Deduce, using Kirchoff's voltage law and Laplace Transforms, an expression for the transient circuit current. 2. Using the equation obtained in 1. deduce the equations for the transient voltages...

Homework Statement Hi, In some of the diode analysis examples that we did in class, we often end up with circuits like the ones shown here. I'm quite confused because sometimes I understand them and other times I just don't know how these voltages are coming from. It really makes me question...

Homework Statement In the circuit above ##E_1=E_2=E_3##, ##Ig_1=Ig_2=Ig_3## and ##R_1=R_2=R_3=R_4##. In the case when the switched is closed the power of the ideal generator ##E_2## equals ##P_{E_2}=-30W##. Then the switch opens. Calculate the ##ΔP_{E_1}##. Homework Equations 3. The Attempt...

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...

Homework Statement Hi everyone, I'm just having a little trouble with equivalent resistance in a bridge, in the image I attached. The textbook says that the way to solve this is to put R3 and ZL2 in series, that series is in parallel to the short circuit in diagonal, and then at the end we...

My question applies to the case when the switch opens. By applying KCL in order to get a first order diff equation, the following problem arises when I choose different current directions (which shouldn't happen because KCL says the current direction doesn't matter because it will be fixed...

Is it possible to have one part of the circuit running with electricity then manually add in a second part of the circuit to the first part and have both running simultaneously? Is there a name for such a circuit? The voltage and current of the first part of the circuit would change because of...

Hi guys, I recently finished my Physics undergraduate degree, and will be starting my first job in September. My employers have asked me to improve my knowledge of electronics before I begin work. I would like to improve my ability to analyse and understand circuits, and also learn more about...

Homework Statement I need to find the voltages (if any) and currents of these circuit, but particularly Io I do know that I have to use KCL bot I don't know how, can somebody help me with a node or somethinghttps://www.physicsforums.com/attachments/c2-jpg.80412/ I do not have any other info...

1. Homework Statement Establish the condition required to make the current through Ze in Figure 1 zero (i.e. For the voltage Vx to equal Vy). Homework EquationsThe Attempt at a Solution I'm not sure if I'm on the right line here, hopefully someone can point me in the right direction if it's...

Hi.i know that a ideal current source has infinite resistance and it supply's constant current to aload connected across it. The current source doesn't have the infinite resistance in series to it but in pparalle. All is well until I think of this Norton's Therom. When we transform a voltage...

Homework Statement the voltage Vc in the figure is always equal to 2 Relevant equations The Attempt at a Solution From kirchhoffs law, -Vc+4+5=0 Vc=9 V will Vc always equal to 9 V or it will vary?

Homework Statement P 1.2-4 Homework Equations I know that i(t) [current w/respect to time] = dq/dt. I also know that by the previous equation, q(t) = ∫i(τ) from -∞ to t (sec). The Attempt at a Solution I understand simpler problems involving finding q(t) by using the integral relationship...

Which is the best book for electrical circuit theory?

Homework Statement Here's the problem: Find the equivalent conductance Geq and then the equivalent resistance Req "seen" by the current source Is in the circuit in terms of the literals R1, R2, and gm. Figure: Homework Equations Ohm's Law: V = IR KVL: V1 + V2 + ... Vn = 0...

antenna circuit theory help! Im having trouble understanding vswr and current path in an antenna system. Example is the dipole...Ive read that the parasitic capacitance between the 2 wires forms the complete circuit but then I read about standing waves that reflect at the open circuit. My...

I am under the impression that if you have an inductor and a resistor connected in series with a DC supply, that at the instant the switch is closed, the minimum current that circuit will flow, is flowing at this time? kirchoff's law for the circuit... Vsource - Ldi/dt - Ri = 0 therefore...

i m trying to solve this question by method given in most of the standard books i.e. Vc(t) = Vc(\infty) - [Vc(0\hat{}-) - Vc(\infty) ] e \hat{} -t/RC first i found Vc(0\hat{}-) by considering switch open and inductor behaving like short and capacitor open at steady state...then i find...

Homework Statement In last weeks lab, I was asked to find the resistance of two unknown resistors. I hooked them up in series with a 10V source and measured the current across each one. The ammeter read 5.77 mA at Rx and .014 mA at Ry. Shouldn't the ammeter have read the same value at both...

Can someone help me? In the attached file to resolve that one or more of the questions? When I am in a situation very difficult and very few I do not know the answers to the following questions (the problem statement?? relevant equations...) Because I am a former student at the university...

Homework Statement http://img265.imageshack.us/img265/8616/43354308.png I have an exam coming up in a few days and I am doing some revision questions from some past exams and this is one I have attempted but I have no solutions to check my answers. The Attempt at a Solution using Vs = 12cos(...

I'd like to learn about how the fundamentals of how power works and how circuit theory works, while actually keeping a continuum between the fundamentals. In otherwords, I picked up a book on circuit theory, and it was filled with rules with no physics-backed explanations. I understand some...

Homework Statement It's a simple AC circuit with a 100ohm resistor and a 10mH inductor connected in series. The voltage is given as a function rather than a quantity: V = 20sin (5000t). Problem asks to find the peak current in the circuit. Homework Equations i = integral (V/L)dt Z = sqrt...

it's only the second day of class but my professor assigned some problems that are those weird ones that neither he nor the book even discusses, I have tried several different methods including parametric graphing, integrating the functions, deriving the function, but to not even the slightest...

Why do we take ideal voltage source to have 0 impedance and ideal current source to have infinite impedance. Please explain mathematically also!

Hey all. I've never really done anything in the way of circuit theory up until now, where i have just started a unit on introduction to electrical/electronic engineering. Lets say i have a 60W light globe. Does this mean that the maximum power it can dissipate is 60W, after which it will...

Homework Statement I have attached the circuit diagram to this post. I have to find i which I have shown in the diagram. All the voltage and resistor values are also given. Homework Equations The Attempt at a Solution I tried finding the current for the whole circuit which would...

Hi, Can anybody solve attached problems for me.

http://img442.imageshack.us/img442/2070/circuit1vf1.gif i drew this from a superposition question.. the voltage source is shorted out. what on Earth could Ia be if there's no voltage source?

Hey, I'm having a bit of difficulty with this specific circuit theory problem... We understand the basics, Ohm's law, Kirchoff's voltage and current laws, voltage and current division... I'm just confused about what to do with this problem: Find the value of Vx in the circuit below such that...

This bothers me every time I study circuits, currently introductory level. I can solve problems just fine, but something is just not "clicking" here. Mostly conventions for things like current, power absorption, etc... Is there some where an explanation of what actually happens in a...

Hi, Are there ways to use/reduce electromagnetic theory to understand circuit theory better? ie use circuit theory as a special case of em theory? if so can you suggest books which do it this way? basically my idea is to look at any circuit from the general point of view - using the physics of...