Questions tagged [kirchhoffs-laws]

Kirchhoff's circuit laws deal with the conservation of charge and energy in a circuit.

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I need help finding the power

I need help finding the power of the 1 ohm resistor in this circuit. Could you guys give any tips or even some clues to find it ? I've been trying for a while with Kirchhoff's circuit laws but ...
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Converting a schematic to a graph [part 3]

This is part 3 in my journeys to try and graph a basic resistor circuit programmatically (part 1 and part 2. I think I have finally figured out how to treat components -- which if I looked at any ...
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Determining gain, KCL/KWL (Basics)

Below is a pi model schematic of a cascaded amplifier. The goal is to find the gain with Rp as load. So the gain would be: \$ A = \frac{V_{out}}{V_{in}}\$. So i set out to find \$V_{out}\$ in terms ...
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How do we know that current doesn't get “stuck” in junctions?

I know the question might sound slighly basic, but stay with me here. Kirchoff's Current Law states that "The algebraic sum of currents in a network of conductors meeting at a point is zero." ...
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Converting a schematic to a graph

This is a follow up to the question about I posted last night, Converting a schematic into a graph. From some of the answer, I was able to re-work how the graph is done -- with components as edges and ...
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Single phase neutral current & three-phase neutral current with respect to kirchhoff's law

In the below schematic, would be the sum of all current in the single phase neutral wires equal to the current in neutral wire going to the 3 phase main disconnect? In theory, we know that if the 3 ...
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Converting a schematic into a graph

I've been working for some time trying to figure out how it might be possible to translate a schematic into something like a node graph, where each node is a component. I've taken some liberties in ...
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1answer
41 views

Node analysis: estimating variable current branches

Is there a way to get the number of potential currents that could be in a circuit? (Note: in the following circuits ignore the Resistor value, I've just added a resistor with the default schematic ...
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28 views

Verification of power law

Here is the solution that I have so far. How are the values of Vx different if we solve it using KVL and different if we use Ohms Law? And to verify the power law, do i need to calculate the ...
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I need to verify the power law in this question

Question. I suppose the value of Vx must be positive. So how do I manipulate the equation such that Vx becomes positive? Can this be the solution to this question?
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What exactly is this question asking us to do?

Based on the model and circuit shown in Fig. 2, draw a circuit model of the path of current through the human body for a person touching a voltage source with both hands who has both feet at the same ...
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How do I calculate i, i1, i2 and v2?

I'm unable to figure out how to use the current dependant voltage source in KVL The following are the equations I've found, up till now: 20i+V2=10, V2=50i1, 20i+50i1=10, i=i1+i2
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Solving for current with voltage drops

Given the following circuit: Why is the current through the circuit 34.7mA instead of 35 mA? My thinking was that: The LED draws two volts, so it effectively makes the battery 7V instead of 9V. ...
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the transconductance of cascade MOSFET IF channel length modulation is NOT ZERO

What would the derivation of the cascode MOSFET transconductance in small signal analysis IF THE CHANNEL LENGTH MODULATION IS NOT ZERO, as most examples for the cascode mosfet transconductance say in ...
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Lumped model not applying to PCBs

Recently I have heard that KCL and KVL do not fully apply when performing electrical measurement on PCB traces. It was implied that PCBs are not completely lumped circuits - that is, we cannot assume ...
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Reasoning behind equations in analysis of electrical circuit

I am currently studying the mathematics textbook Nonlinear Dynamics and Chaos by Strogatz. As part of an example, I am provided with the following electrical circuit and accompanying explanation: ...
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Solving simple parallel/series without Req

Given the following circuit with three resistors, R1=100Ω, R2=200Ω, R3=300Ω: To solve this using the \$R_{eq}\$ trick: ...
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78 views

Substitution + Superposition with RLC circuits

Consider the following circuit: simulate this circuit – Schematic created using CircuitLab \$E\$ is a constant voltage source. The switch is closed at time \$t = 0\$. The request is to ...
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Number of independent KVL and KCL

I know that the number of KTL and KCL is related to the number of nodes \$N\$. For KCL there are \$N-1\$ equations while for the KTL there are \$L-(N-1)=L-N+1\$ equations. However I didn't understand ...
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Kirchhoff's Rules

Can a kirchhoff circuit reduce to a single resistor connected to more than 1 battery?
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Circuit Analysis of an Outlet Tester

I have an Outlet Tester like this: It is used to see the mains electric connection, it has the next states: I opened it and then I reversed engineer it. The diagram I obtained is this: I would like ...
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35 views

Position of the voltage source with parallel resistors

In the following circuit I want to calculate the current flowing through the voltage source (node A) simulate this circuit – Schematic created using CircuitLab If I use the KCL I get \$I_A = ...
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3answers
57 views

Current flowing in a short circuit with a voltage source

I want to calculate the current flowing in the node A of the following circuit: simulate this circuit – Schematic created using CircuitLab This can be approached in several ways. The tension ...
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1answer
56 views

Kirchhoff's Laws exercise

So I am solving this exercise. The problem given is to calculate the Voltage between ab. I calculate to 16V but the answer is 4V. I found out that they did not include Voltage between eb. I wonder why ...
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In search for more Exercises

I'm currently studying in Germany for Electrical Engineering (course in English). Due to incoming exam, I am looking for more exercise material as although my course is in English, the school library ...
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42 views

Why doesn't KVL work for the bottom loop?

I was doing a practice problem. I calculated the correct value for i_a = -2.4 A. But I used KVL on the bottom loop to get R, and got the inverse of the answer that I actually needed. My equation was -...
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71 views

Simple circuit analysis with node potential method

I can't find the correct solution for this exercise and I can't figure out why. simulate this circuit – Schematic created using CircuitLab The question is: What is the current \$I_3\$ ? (...
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Difficulties in KVL signs (RL circuit)

If we start from bottom left and rotate clockwise, then first we visit resistor negative terminal so I expect -Ri but the book says the below equation: So why ...
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Correct equation for describing *exactly* the output of a current follower

In the textbook I use for teaching Instrumental Methods to Analytical Chemistry, there is a discussion about current follower circuits based upon the following figure: After describing the ideal ...
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Dependent current source Mesh Analysis challanging problem

\$I\$ \$2\$ gets different value by different equations , Using mesh analysis . Please explain why \$I\$ \$2\$ has two different values using mesh analysis . My approach : \$-12I1+2I2=0\$ \$-2I2+...
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How to compute resistors values in bipolar transistor circuit?

In the attached image, I have this circuit and I need to make the D1 and D2 diodes to work complementary to D3 and D4 based on button status. The problem is that I don't know how to find the resistor ...
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Circuit Analysis: Difficulty in obtaining a current through a resistor?

I'm solving a problem that requires I compute some impedances, and then the current through a resistor. I obtained some of the impedances*, but don't know how to get the second part (current). ...
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How to apply Kirchoff laws to form differential equation for RC circuit with a variable applied 2nd voltage?

I'm trying to create a model for how a capacitor charges and discharges in an RC circuit in response to an applied "control voltage" V2. For this, I want to form ...
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DRV8889: Unexpected voltage drop at output

I'm getting some unexpected behaviors when it comes to the voltage and current I see at the AOUTx and BOUTx pins. I must be missing something from my calculations from the datasheet. Right now, I'm ...
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1answer
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Circuit doesn't seem to add up under Kirchhoff's laws

I'm supposed to do a full circuit analysis of the circuit above for homework, giving all voltages and amperages, but I cant figure it out because the elements don't seem to add up under Kirchhoff's ...
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How to calculate current into GPIO pin after voltage division

I want to use my Raspberry Pi as a remote power management device to turn my home server on and off. I would also like to monitor whether the server is on or off by using the power LED pins on the ...
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Calculate the current

I was practicing for the exam suddenly I found this question the professor solved, but I think whether he or I made a mistake. Part (III) in the image. His calculation is on the image he added the ...
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220 views

Kirchhoff’s Law and Superposition Theorem

For the given circuit I found the current and the voltage at R1, R2, R3, using the superposition theorem. 1.I replaced the VS2 with a short then calculated: I1= 0.57mA, I2=0.33mA, I3=0.2mA, V1= 2.68V, ...
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How to get power in dependent voltage source?

l've made a simple circuit using Thevenin's theorem, and then help me which node to formulate to solve the problem. (I've written Thevenin's theorem, am I writing it correctly?) Also, Vx is a ...
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Current Source and Short Circuit

let's consider this circuit: How can I analyze it? Which is the expression of the current in the short circuit? Is it correct to split the circuit in the following way (I always did it when there was ...
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111 views

How to calculate the voltage across Va and Vb?

Attached is the circuit I have been analyzing. Here the intention is to calculate the voltage across V_A and V_B - (See the red colored letters in the circuit diagram.) I have calculated V_R1 using ...
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Consistently assigning electrode nodes in random resistor networks

In the context of random resistor networks, the general question of interest is often "what is the effective resistance between two arbitrarily chosen nodes?" But more specifically about the nodes we ...
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Find the voltage across dependant current source

The question attached in the image : I have found the I in the left loop I=1.19A then I found the vo=-11.9 Here two questions in my mind : 1)does that mean that the voltage across the top resistor ...
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Finding a current in a given circuit

The problem has given the following circuit: And asked to find the value(s) of Ix if the elements absorb the power(s) given. I tired to set up KCL/KVL but I keep getting stuck. I first drew this: ...
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Cascading/multiple voltage dividers

Could someone explain the voltage readings on the following "oscilloscopes" of the simulated schematics below: (I understand the concept of a voltage divider but it seems something less ...
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What is wrong about this application of Kirchhoffs Current Law?

At a recent exam I had this very simple problem concerning Kirchhoffs Laws: I am concerned with problem c Now my understanding of this is: I can combine both nodes, and since all currents in the ...
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Potentiometer Working

Let's suppose that \$E \gt V\$. Now, the voltage \$V_b\$ at point \$b\$ will always be \$V\$ and will not depend on \$E\$. Similarly the voltage \$V_A\$ at point \$A\$ is \$V_E\$ which will be ...
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214 views

nodal analysis, current direction

Right, first the diagram, I tried using the schematic function,but it never actually added the schematic. I picked this because it illustrates my confusion in the simplest schematic I could find. We'...
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Finding the output of a node with two diodes (kind of full-wave rectifier)

Maybe this question sound stupid, but I really suck at electronics. I have this circuit here: simulate this circuit – Schematic created using CircuitLab and i want to find the values of ...
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Performing small signal ac analysis with non-linear components

I have written a circuit simulator that uses Kirchoff's voltage and current laws to solve linear circuits containing capacitors, resistors, inductors and op-amps (where the op-amps are assumed to be ...

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