What is Kvl: Definition and 92 Discussions

Kirchhoff's circuit laws are two equalities that deal with the current and potential difference (commonly known as voltage) in the lumped element model of electrical circuits. They were first described in 1845 by German physicist Gustav Kirchhoff. This generalized the work of Georg Ohm and preceded the work of James Clerk Maxwell. Widely used in electrical engineering, they are also called Kirchhoff's rules or simply Kirchhoff's laws. These laws can be applied in time and frequency domains and form the basis for network analysis.
Both of Kirchhoff's laws can be understood as corollaries of Maxwell's equations in the low-frequency limit. They are accurate for DC circuits, and for AC circuits at frequencies where the wavelengths of electromagnetic radiation are very large compared to the circuits.

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  1. A

    KVL Exercise: Basic Homework Statement & Solution

    Homework Statement Click on the link https://www.diigo.com/item/image/2sb3i/yjim Homework Equations KVL Law Similar Example : https://www.diigo.com/item/image/2sb3i/orwa The Attempt at a Solution (a) In the left loop : -8-12+VR2 = 0 VR2 = -20 v (b) In the big loop ...
  2. C

    KVL Node Voltage: Positive vs Negative Assumption in Homework Solution

    Homework Statement Homework Equations ƩCurrent(in) = ƩCurrent(out) The Attempt at a Solution ----In situations like that, my book takes the node to be a positive voltage when the voltage source is connected like above. For some reason my professor takes it to be negative, is this why my...
  3. C

    Use Ohm's law and KVL to find the value of R:

    Homework Statement http://img853.imageshack.us/img853/2038/homeworkprob18.jpg (everything copied above is as given, except 'I3' was supposed to just be 'I', but more simple for me if 'I3') Use Ohm's law and KVL to find the value of RHomework Equations V= IR KVL, and maybe KCL: KVL =...
  4. H

    Application of Circuit laws (KCL and KVL)

    Homework Statement Calculate the resistance of this combination of resistorsHomework Equations V=IRThe Attempt at a Solution By using KVL : V= 3I_{5} = I_{2} = 2I_{4} I = I_{1} + I_{2} I_{3} = I_{2} + I_{4} I_{1} = I_{5} + I_{4} I = I_{3} + I_{5}Now the final result could be obtained by the...
  5. P

    KVL Confusion: Voltages & Arrows Explained

    http://www.flickr.com/photos/53512951@N06/8229416013/in/photostream/ With regards to the circuit in the image linked above, I have been told to start in the bottom left hand corner and then work clockwise around the circuit, adding up all the voltages to see if they follow the KVL principle...
  6. T

    KVL question for multiple loops

    Hi, The picture below is part of the notes given to us by our teacher. In case it doesn't work, it's a double loop with a voltage source on the left arm, a resistor (R1) on the middle arm, and two resistors in series (R2 and R3) on the right arm. all the resistors and the voltage source are...
  7. A

    KVL in AC Circuits: Exploring Accuracy

    Hello, Why do we use KVL in Ac circuits ?! or to be more specific is it accurate to use it in Ac circuit , just the same accuracy as using it in Dc ?! Doesn't the current that pass through the circuit itself make it's own variable magnetic field , which crosses the loop of the circle ...
  8. N

    Best choice of KVL and KCL in a circuit

    Hi everyone! Since this is very confusing for me, i wanted to know what is the best choice to take in choosing the kvl and kcl. The questions are ? How many KVL and KCL i should take ?? ( best number, without redundance) And is there a way to see if a kvl or kcl is linear dependent on...
  9. Y

    Electrical eng, my vectors for KVL and KCL aren't adding up - no errors in math

    I've been asked to prove KVL and KCL using this circuit, but my vectors don't add up. ei Vr1+ Vr2 + Vc1+Vc2 ≠ Vtotal, same goes for Current, but I at least got the correct angle for the current Tried using vector addition, using addition of the vectors in complex form and even tried using this...
  10. T

    Engineering Need help with a really basic electrical circuit(KCL, KVL, Ohm's law)

    Homework Statement I should find i1 and i2. Homework Equations V = R*I KCL KVL The Attempt at a Solution I have no idea where to even start, so I tried doing different things, but nothing that I do works. I am just really frustrated right now, for failing at doing such a simple thing. I...
  11. V

    Confusion in using KVL (assigning polarities) in a problem

    This is actually a solved example of Thevenin's principle in my textbook and I understand all of it except the part that I'm attaching to this post below; the part where KVL (Kirchoff's Voltage Law) is applied. Homework Statement Find Eth in the circuit shown in the attached figure...
  12. N

    Nodal Analysis - KVL Loop question.

    Homework Statement I've obtained the node equations that's in the matrix for rows 1, 2, and 4. I got 3 as well but I'm not sure if my analysis was correct. http://img252.imageshack.us/img252/3151/nodeq.jpg The Attempt at a Solution http://img684.imageshack.us/img684/9803/dsc0010van.jpg So...
  13. A

    3 batteries, 5 resistors using KCL & KVL

    Homework Statement 1. Using Kirchhoff’s Laws, find all the currents flowing in the circuit. 2. Hence, determine the voltage across each resistor and show that all loops comply with KVL Homework Equations KVL and KCL The Attempt at a Solution Please see the pictures...
  14. S

    Contradiction in Common BJT Configuration: KVL vs Early Effect

    Now as you can see in the picture a common base configuration of BJT. The green markings in the picture are resistances. :p My question is: By KVL : VBB = VBE + IE*RB which means that IE is esentially a constant because VBB , VBE, RB are constants. Now If Voltage Vcb is increased Early...
  15. C

    Solving KVL and KCL: Can I Say I1 = -I2?

    Homework Statement Please check attachment or picture below http://i.imgur.com/7Op7H.png Homework Equations KVL, KCL The Attempt at a Solution I try to solve KVL and KCL equations. I didn't get any of answer above. Can I say I1 = -I2? Thanks!
  16. P

    Calculating v_0 and i_0 with KVL & Ohm's Law

    Homework Statement In the figure, calculate v_0 and i_0 when v_s = 1 Homework Equations Using Mesh Currents: KVL: The sum of all voltages around a closed loop is equal to zero. Ohm's Law: V = IR Cramer's Rule: i2 = delta2/deltaThe Attempt at a Solution I first designated the lower left loop...
  17. F

    KVL & Node Voltages: Verifying Ans. to I

    Homework Statement [PLAIN]http://img163.imageshack.us/img163/408/circuit2w.jpg We are asked to solve for I. I found I = -4 Amps. I want to verify my answer using KVL in the bottom left mesh Homework Equations KVLThe Attempt at a Solution I follow the convention: voltage drops are positive...
  18. S

    Can a Mistake in KVL Analysis Disprove a Fundamental Law?

    Here's my work. When I apply KVL around loop 1, I get +5V, but when I apply it around loop 2, I get -5, which is inconsistent with my first results? Where am I going wrong, or have I disproved a fundamental law?
  19. R

    Engineering Simple question about KVL Equation in a BJT Circuit

    Homework Statement I am trying to find the KVL equation for this BJT in order to find Ib. http://www.ece.auckland.ac.nz/oasis/a/att/qtatt/2028/2/261/IM010 Homework Equations The Attempt at a Solution My current equation looks like this. Vcc - IcRc - IbRb - Vbe = 0 I am...
  20. A

    Learning Ohm's Law, KVL & KCL for Biomedical Engineering

    Hi, I just took up a course on biomedical engineering. And i have no background knowledge on engineering, having difficulty in following up in class. Can anyone teach me the basic? i was studying on transducer (sensor/actuator), focusing more on sensor. Ohm's law, KVL, KCL, voltage...
  21. T

    Understanding Polarities in Inductors and Capacitors in KVL

    i generally get confused in polarities of inductors and capacitors while doing KVL. eg about a series RLC circuit ,the equation turns out to be ( Ldi/dt + iR + Vc = 0 ) this is the equation about assumed 'i' if we assume both capacitor and inductor in charging mode... ... what if I assume...
  22. F

    Solving for multiple unkowns using KVL and KCL equations

    Homework Statement I am asked to solve for vX, PDEV BY iS1, P ABS BY vS3 (please see attached figure). We have only covered KCL, KVL, Ohm's law and Power in class. No Thevinen theorem, so it can't be used to help solve. The Attempt at a Solution I know that current will...
  23. PainterGuy

    Simple circuit analysis using KVL

    Hi, :smile: Please have a see on this circuit diagram: http://img192.imageshack.us/img192/7726/meshkvl.jpg I used these equations: 1: I1 = I2 + I3 (Using KCL at junction e) 2: 6 - 4I2 + 4 - 2I2 = 0 (Using KVL around afeba) 3: 3 - 6I3 - 4 - 4I2 = 0 (Using KVL around dcbed) I2 = 2.8 A I1 = 4.5...
  24. PainterGuy

    Simple KVL (kirchhoff's voltage law) problem

    hello everyone,:wink: my book says: \sum E = \sum IR where E is emf. it says the sum of all emfs equal sum of all IR terms. 1:-- please have a look on this PDF...
  25. J

    Engineering How Do You Correctly Calculate Vk in a Basic Circuit Using KVL?

    Homework Statement Find the value of Vk http://oi54.tinypic.com/2s6x005.jpg Homework Equations The Attempt at a Solution Assuming dependent Vk = 12i -60 + 4i + 12i + 12i = 0 -60 + 28i = 0 i = 2.14 Vk = 12 * 2.14 = 25 .68 ? Answer is 18. Can someone tell me where I am going wrong ?
  26. S

    Solving a Circuit Diagram with KVL & KCL

    Here is my circuit diagram. http://s1227.photobucket.com/albums/ee430/Shayaan_Mustafa/?action=view&current=untitled-1.jpg&t=1299237316875 I am unable to solve my circuit with the help of Kirchhoff's law: Here is my KVL equations: 24-v1-v3-v8=0------(1) v3-v2-v4-v7=0------(2)...
  27. C

    Engineering Understanding KVL and KCL for Circuit Analysis

    Homework Statement Basically, find Vab [PLAIN]http://carlodelmundo.com/hw/circuit.png Is this correct -- note: please tell me that my methodology is sound; DO NOT GIVE ME A NUMERICAL ANSWER. The problem asks for VAB. What's weird to me is that there is a potential across two...
  28. T

    Understanding KVL and Voltage Differences

    Homework Statement Homework Equations KVL, the sum of all voltages around a loop equal 0The Attempt at a Solution Vx is just the difference of the bottom node to the right node. With KVL I just add up the the voltage differences in a loop and equal to zero right? -15+12+6+Vx=0 Vx = -3 ...
  29. S

    How do I do this with KCL and KVL

    Homework Statement http://i139.photobucket.com/albums/q292/strkthug/KCL/kclandkvl.png Homework Equations The Attempt at a Solution I think since x2 is 2a and x3 is 3a then x5 should be 5a and I have no idead where to go from there
  30. E

    Two Parallel Voltage sources and KVL

    Hi, I understand that you cannot apply KVL to voltage sources connected in parallel, unless both voltage sources are the same, as this violates KVL. However, I want to know why? Just a simple 2-3 line explanation will suffice. Regards
  31. N

    Kvl Left Side: Can't Understand Member?

    i can't understand how they how the member of which i point too
  32. N

    How to get to this KVL expression

    in this photo there is the circuit and the KVL of the solution but when i tried to do the KVL i go from the arc(3 lines represents potential zero) in counter clockwise direction so i get V_L + V_C+V_R-V_s=0 when i go against the direction of a current the voltage is on PLUS when in the...
  33. N

    Contradiction on kvl kcl laws question

    http://i49.tinypic.com/1yu634.jpg this is a part of the solution " the is a voltage drop on capacitor C1 which makes current shock on C1 and a current shock on R2 and R3 and it makes a KVL contradiction on the right branch and the outer branch. and that's why the continuety laws...
  34. O

    Simple KVL, KCL and Ohm's Law problems

    Given: In the circuit shown above, 192 V is dropped across the unknown resistor, Ro. Required: Determine the value of Ro. V = iR, KCL and KVL I really don't know where to go on this one. I know that the right side's voltage will need to add up to zero, but that's about all I know.
  35. C

    Why is the equation for KVL not -vR + vL = 0 in this RL circuit?

    Homework Statement Not really a problem, but we're learning about source-free RL circuits and the instructor was deriving the current w.r.t time. I've actually seen this derived a few times but one thing has always bothered me. Looking at this picture recreated from the text...
  36. T

    KVL with a current source in loop

    I'm trying to solve for a number of different currents in a circuit, and I'm wondering how to do KVL with a current source in a loop? The current source is actually part of two loops, so is it possible to just name the current source 'V' during KVL and add (or subtract) the two resulting...
  37. S

    Engineering Basic Circuit Problems - KVL and KCL

    Homework Statement Find R_2 in the circuit below. http://img214.imageshack.us/img214/6396/circuithh3.jpg Homework Equations Kirchoff's Current Law: \sum {I_{IN} } = \sum {I_{OUT} } Kirchoff's Voltage Law: \sum {V = 0}The Attempt at a Solution Using KCL for the node joining the 8ohm...
  38. X

    Engineering Applying KVL and KCL in Electrical Circuits: A Comprehensive Guide

    For this question I was thinking about doing KVL around the entire circuit, or do Mesh in the individual loops. Any suggestions?
  39. T

    Two electricity questions about KVL and a pole numbers

    What happens when you do a KVL through and current source? A formula I can not understand ns=120*f/p f=frequency P=number of poles ….. How shall you know how many poles you got?, my old teacher just wrote it down as it would be obvious. But I think ti is related to what kind of...
  40. L

    Thread about the MIT prof claiming an incorrect usage of KVL in RL circuits

    There was a thread where the thread starter pointed out a video lecture where a MIT prof claimed that KVL was incorrectly used in the analysis of self inductive circuits in almost all textbooks. I thought it was an interesting read and wanted more opinions on the idea, however I cannot find the...
  41. R

    Where to Find Solved KCL and KVL Problems for DC Circuits?

    help! KVL and KCL SOLVED PROBLEMS! undefinedundefinedundefined I need some websites of solved problems containing KCL and KVL in a simple DC circuit...please post some links! thanks!
  42. D

    How do you represent a dependent current source in a parallel circuit using KCL?

    Quick question that is throwing me off... If you have a dependant current source in a parallel circuit, how do you represent that in your KCL equation? The one in this problem is Vo/2000. I took that as I=V/R so R=2000. Since it is in a parallel circuit on its own 'branch' I used Vs/2000...
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