Questions tagged [kirchhoffs-laws]

Kirchhoff's circuit laws are important for circuit analysis. There are two laws: Kirchhoff's Current Law (KCL) and Kirchhoff's Voltage Law (KVL). KCL states that the sum of currents flowing into a node is zero, and KVL states that the directed sum of voltages around a closed loop is zero. Consider also using the "circuit-analysis" with this tag.

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Determining currents in each part of the circuit using Kirchhoff 's laws

During this question I have applied the junction rule and the loop rule but I am stuck on the next stage: I1 = I2 + I3 Loop 1 and 2 will be both in the clockwise direction. Loop 1: 30 - 8·I1 - 6·I2 = ...
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3 votes
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340 views

Monopole antenna: does current flow in loops?

I've been wondering for the longest time about how a monopole antenna (like the one in a typical FM radio) can work without offering a return path for current. I have a hypothesis, and I'd really ...
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Current direction inconsistency in Nodal Analysis

I'm very confused here! Most of the times I'm getting wrong answers or impossible equations because of this - even if I know the procedures for the analysis. It has to do with setting up nodal ...
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Applying KVL in loops

So, this is sort of a basic question but I keep getting this wrong somehow. The Kirchhoff's voltage law says that the source voltage is equal to sum of all voltage drops and mathematically it is ...
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How does Kirchoff's current law work for sinusoidal voltage sources?

I was solving a steady state question with sinusoidal AC voltage source and the solution for the question used Kirchoff's current law to find the nodal voltage of a node. Now, I used to think that I ...
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Why isn't my application of KVL working here

Firstly, please note that this is a high school level, physics question, but as this is related to circuits, I feel this is a better place for such a question than PSE. The image is from byjus and ...
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How to find an equivalent LC circuit from a combination LC circuit [closed]

I have a circuit containing a number of L and C, both in parallel and series. How can I find the equivalent LC circuit (with a single L and C) for such a circuit? Kirchhoff or Thevenin can give me the ...
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Interpretation of Generation and load power at a bus and understanding of slack bus

I was going through the IEEE 14 bus system data from [here] (https://ijireeice.com/wp-content/uploads/2013/03/IJIREEICE2E-a-shkti-Computation-of-final-21.6.14.pdf). I know that there are three type of ...
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Kirchhoff's law question

Can someone please help me to solve this problem? I tried to solve it:
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2 votes
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Current Direction and Voltage Polarity in Capacitor/Inductor Circuits

I believe that this question may be simple for those with a little more experience, but it is still puzzling me. Studying capacitance/inductance, I understand that the capacitor in the DC case behaves ...
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How do I find Vo in the circuit?

I1 + I2 = I3 I1 = Vi/Z1 ... Z1 = (1+sCR1)/sC I1= Vi(sC)/(1+sCR1) I2= Vi/R1 I3= -Vo/R1 I1 + I2 = I3 Vi[(sc)/(1+sCR1) + (1/R1)] =-Vo/R1 -Vi[(R1sC)/(1+sCR1) + 1] = Vo How do I change back to time domain?
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State-Space Model of Resonant Circuit

I am trying to determine the state-space model of the circuit shown below. Also shown are the KH equations. Those equations I put in a Solver (Mathcad), however the result does not seem correct. For ...
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Op-Amp nodal analysis

Why is i20 = (Va-Vb)/20k, not Va/20k?
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Is it normal that an analog voltmeter has about 7K ohm input impedance?

I have bought 10V 6c2 DC analog voltmeter, and I have tested it with a regulated DC power supply and it measured pretty accurately different voltages, however when I tried measuring the voltages in a ...
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2 answers
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Double loop, double voltage source circuit analysis problem, with three unknown voltages/currents, using Kirchhoff's laws and Ohm's law [Post #2]

I recently asked this question: Find the currents and voltages in the circuit shown in Fig. 2.28. Answer: \$v_1 = 6 \ \text{V}\$, \$v_2 = 4 \ \text{V}\$, \$v_3 = 10 \ \text{V}\$, \$i_1 = 3 \ \text{A}...
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How can I solve the following phasor analysis question?

How can I solve part B? Obviously, since the two sources have different frequencies I started off by killing the voltage source (short-circuit) and then tried to apply KCL. My goal was to find the ...
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1 vote
2 answers
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How do we find the current in this circuit?

How do I find the current drawn by the 11V in this circuit? I understand that the circuit can be redrawn but I do not understand the simplifying procedures to do so.
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Current distribution in a circuit that includes current and voltage sources

The question asks us to find \$ V_{c1} \$ and \$ V_{c2} \$ . The equivalent circuit is below. My lecturer drew the currents as in the picture. And here is my lecturer's solution for calculating the ...
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Problem with determining currents in multi-source circuit

I need to solve the circuit shown below: simulate this circuit – Schematic created using CircuitLab And here is my attempt. I'm sure my attempt is wrong here but I'm not really sure why. I've ...
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Double loop, double voltage source circuit analysis problem, with three unknown voltages/currents, using Kirchhoff's laws and Ohm's law

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 2.4 Kirchhoff's Laws has the following practice problem: Find the ...
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Two seemingly analogous cases of using Kirchhoff's current law to calculate current through a node

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 2.4 Kirchhoff's Laws has the following practice problems: Find ...
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Calculating voltages around circuit by using Kirchhoff's voltage law and Ohm's law

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 2.4 Kirchhoff's Laws has the following practice problem: Find \$...
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Adding ground to the minus of the source

I'm currently learning Kirchhoff's law and a circuit shown in the picture came up. I had tested it in a circuit simulator and no current was shown to leak to the groud. Could anyone explain what ...
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Nodal and Mesh analysis

I need to find the currents on each resistor of this circuit: Where \$\beta\$ is a constant with units of resistance. Applying Kirchhoff's laws the equations are: $$ I_1+I_3-I_2 = 0 $$ $$ V_0-I_1R_1-...
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Is it right to consider these resistors in this way? [duplicate]

If we short circuit all voltage sources and consider all the resistors but RL, the same current is flowing though R1 and R2 (they are in series) and they are in parallel with R3 and R4. Is it correct? ...
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Mesh Current Method and Analysis DC

This is my approach so far: simulate this circuit – Schematic created using CircuitLab I'm having problems with the third loop, only because of the fact that there are two batteries that are ...
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2 answers
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Kirchoff law circuit exercise [closed]

Hi I am starting to study electronic circuits and I found an exercise with this circuit. Now, I don't really care about the numeric results, I care more about understanding how to solve this kind of ...
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The sign on each voltage is the polarity of the terminal encountered first as we travel around the loop?

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 2.4 Kirchhoff's Laws says the following: Kirchhoff's voltage law (...
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2 votes
2 answers
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Does an ideal voltage source go against Kirchhoff's voltage law?

Very new to electronics. Stuck on this topic: In a circuit with zero resistance an ideal voltage source of example 5 volts will produce 5 volts, since ideal voltages don't have an internal resistance. ...
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Why is voltage and current at a node 0?

I am studying through Kirchoff's current law and following with a multimeter. As per the law, I could see the current entering and exiting the node is same, 0.17mA. Also the voltage is 2.56 volts. ...
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Solving the open circuit voltage and voltages not summing up to zero

I tried solving this circuit using mesh analysis. I actually do not understand on how I can find the voltage in the open part. Moreover, the voltages of resistors in some loops are not summing up to ...
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0 votes
9 answers
438 views

A circuit cannot contain two different currents in series; otherwise KCL will be violated

I'm currently studying the textbook Fundamentals of Electric Circuits, 7th edition, by Charles Alexander and Matthew Sadiku. Chapter 2.4 Kirchhoff's Laws gives the following example: Kirchhoff’s ...
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-4 votes
4 answers
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Where is my capacitors energy missing?

To avoid "mistakes", may I recall that, mathematically, \$\infty \times 0 \$ can be ... finite! Otherwise, why use a Dirac impulse? After reading this and this, I have yet a "question&...
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4 votes
3 answers
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Mistake in using KVL and KCL in ideal opamp-circuit

I have the following circuit: simulate this circuit – Schematic created using CircuitLab And I used KCL and KVL to write the following sets of equations: $$ \begin{cases} \text{I}_0=\text{I}_1+\...
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2 votes
2 answers
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Using mesh current method find current and power in 15 Ω and 3 Ω resistor branches of the circuit

I assumed i1 in the left-most mesh, i2 in the right-most mesh and i3 in the top mesh, all clockwise. i2=-2 A from the circuit The equations I got were: from left mesh: 11 - 14 i1 + 12 i2 + 2 i3 = 0 ...
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2 votes
1 answer
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Temperature gradients and different types of wires in thermocouples

I use long (10-m) copper-constantan thermocouples for work to measure temperature. The temperature gradient is only present in the 15 cm nearest the hot junction; the remaining 9.85 m of these ...
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-1 votes
2 answers
113 views

Where do I apply KVL in this given circuit? [closed]

I would like to solve for the unknown voltage and current \$V_x\$ and \$I_x\$. Below is the image of the circuit. Should I first solve the current flowing in resistors 3 and 4 through equations of KVL ...
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0 votes
3 answers
172 views

How do I do KVL on the Input Loop of this Transistor?

The 200Ohm resistor is throwing me off. Is it supposed to be 200Ie, or 200Ib when I do KVL? I have tried simulating the circuit, but that does not alleviate my confusion. Ultimately, I am trying to ...
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0 votes
1 answer
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How to determine two unknown voltage sources

I have this question from my electrical circuits class that i can't get my head around at all. Any help would be appreciated. On the left there is a voltage source of unknown polarity and voltage (...
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1 vote
2 answers
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Find current and voltage through the circuit

Solve using KVL and KCL and find voltages and currents. For this I took $$i_1=i_2+i_3$$ $$v_1=2i_1$$ $$v_2=8i_2$$ $$v_3=4i_3$$ The equations I got by assuming loop 1 and loop 2 were $$5i_2 + i_3 = 5$$...
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1 vote
2 answers
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How does KVL work in this circuit?

I am working through my textbook and came across a KVL scenario that I don't understand. In the problem we were tasked to find the current \$i_x\$ with node voltages. I can follow the solution that is ...
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1 vote
2 answers
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KCL Equation question

Hi I was wondering why the i_A is negative in the answer in the photo, it was the only one that ended up not being right when I did the KCL on my own, what would have been my mistake as to why I ended ...
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How to do mesh analysis when 2 mesh are sharing the same voltage?

I was doing superposition theorem and trying new numericals and then I came across this problem..should I write "9 volts or 9(IsubA-IsubB)" in mesh 1?
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3 votes
1 answer
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Nodal Analysis - Kirchoffs Current Law

Hello, I am stumbling across an issue here. So in Nodal Analysis, we identify our reference point and label the voltage nodes. Then we use KCL to find out equations and solve. My book is providing an ...
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1 answer
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Please help me get this equation part right

Hello everyone, I am understanding the concept of mesh analysis and super meshes. In the Practice problem below, I am presented with a dependent current source and it lies between mesh 2 and mesh 3. ...
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1 vote
1 answer
157 views

Thévenin's theorem exercise

I tried to do an exercise from my textbook where I have to apply the Thevenin theorem, but can't solve it. I got stuck at one point. Given the circuit in the picture find the V0, Vth and Rth. I tried ...
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2 votes
2 answers
136 views

How do I solve this simple circuit using Kirchoff's Laws?

I am a freshman taking up Electronics Engineering and I am brushing up my skills in doing some simple circuit analysis problems. However, I've come across this quite simple problem and my answer is ...
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1 vote
2 answers
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Using current division to find voltage

I'm a beginner in electrical engineering. I am having trouble with this circuit analysis problem. It asks to simplify the circuit into an expression for \$V_L\$ in terms of \$R, R_L,\$ and \$i_S\$. ...
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1 answer
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Big confusion about the very fundamentals of circuit analysis

First, let's call IR3 the current flowing from A to B, IR4 the current flowing from B to C, IR5 the current flowing from C to (-V2). What's the proof that IR3>0, IR4>0 and IR5>0? I know this ...
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-3 votes
1 answer
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Is there any way to simplify this circuit? [closed]

I am trying to get the Voltage across R2, R5. Could someone explain with detailed steps? Thanks
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