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.

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: $$\sum_{k=1}^n I_k = 0$$

KVL states that the directed sum of voltages around a closed loop is zero: $$\sum_{k=1}^n V_k = 0$$

682 questions
177
votes
12 answers

How does the current know how much to flow, before having seen the resistor?

With the following circuits as examples : and How will the current I know how much to flow? Would any other wave travel first in the circuit and then come back and say so much current should flow?
Prabhanjan Naib
  • 1,855
  • 2
  • 12
  • 9
15
votes
6 answers

Current in a circuit is 50% lower than predicted by Kirchhoff's law

I am a math teacher and in my Linear Algebra class we were solving systems of linear equations that come from Kirchhoff's laws. We were trying to use a physical circuit to validate our computations. I did not expect the values to match the…
Tatiana
  • 161
  • 1
  • 5
15
votes
3 answers

How did scientists deal with electronics' problems before Kirchhoff and Ohm's laws?

Both physicists developed really powerful laws which still nowadays rule the electronic behavior of circuits. These help us every day to solve problems, calculate circuit variables… but how did engineers do it before the said laws were discovered?…
xvlaze
  • 273
  • 2
  • 8
13
votes
2 answers

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 node need to cancel out, \$i_c\$ should be 2A. Now my…
peacememories
  • 233
  • 1
  • 6
12
votes
4 answers

Does this experiment show that Kirchhoff's Law hold when there's a changing magnetic field involved in a circuit?

In this video , the electrical engineer and youtuber Mehdi Sadaghdar (ElectroBOOM) disagrees with another video from professor Walter Lewin. Basically, professor Lewin shows in an experiment that if we have two different resistances connected in a…
Hey Hey
  • 223
  • 2
  • 7
12
votes
5 answers

Basics of Transistors

something has been bothering me for awhile. When I look at a circuit involving anything more complicated than RLC components (and perhaps op-amps) I struggle to figure out what it's doing unless its a configuration I've seen before. In contrast, I…
NickHalden
  • 4,217
  • 3
  • 35
  • 41
9
votes
6 answers

Circuit yields a peculiar contradiction between KCL, KVL and Faraday's law

I don't know if this particular circuit/loop is covered in another question but I stumbled upon a video where a peculiar consequence occurs for the following circuit: For the above circuit loop according to Faraday's law of induction one can write:…
cm64
  • 17,348
  • 67
  • 260
  • 471
8
votes
6 answers

Does the current flowing in opposing directions of these two resistors go against Kirchhoff's current law?

I'm studying Thevenin equivalents and need to find the open-circuit voltage between the terminals a and b in the following circuit. I figured since there is no current going to terminal a I could treat the 8 and 12 ohm resistors as being in series.…
Boltu
  • 143
  • 1
  • 7
8
votes
3 answers

How do I decide whether to use Kirchhoff's Voltage Law or Kirchhoff's Current Law?

When I solve questions, I usually get confused between when to use the Kirchhoff's Voltage Law (KVL) and when Kirchhoff's Current Law (KCL). Please help.
user1799
8
votes
4 answers

Can two voltmeters connected to the same terminals show different values? Circuit with induced EMF

The circuit shown below consists of two resistors connected in series that form a closed loop. No electrical sources are in that loop.Let’s assume that the resistance of the wires that connect the resistors and form the loop is zero.Inside the loop…
Slaven Tojić
  • 131
  • 1
  • 9
8
votes
3 answers

Do all components obey Kirchhoff's Current Law?

Kirchhoff's Current Law states that the net current through a node is always 0. AFAIK this derives from conservation of charge principle. My question is, is KCL applicable to any electrical component? For example is it applicable to transistors,…
Utku
  • 1,819
  • 3
  • 22
  • 31
8
votes
4 answers

Explain kirchoff's law in Plain English

I'm having trouble in explaining kirchoff's laws to my cousin who is studying in first year Engineering. Can somebody explain me in simple plain english. Thank you very much in advance :)
pramodc84
  • 183
  • 1
  • 1
  • 5
7
votes
3 answers

Trouble understanding when voltages get split

I am having trouble solving this Op-Amp problem. I'm looking for Vo, and am confused as what to do with the 9V supply and the 2k and 6k resistors. Would the 9V be split between these two resistors? Also, when doing KCL for the V- value, should I…
lm1998
  • 71
  • 1
  • 4
7
votes
3 answers

Solving an ideal opamp-circuit leads to a contradiction

Well, I am trying to analyze the following circuit: simulate this circuit – Schematic created using CircuitLab When I use and apply KCL , I can write the following set of equations: $$ \begin{cases} \text{I}_1+\text{I}_4=\text{I}_2+\text{I}_3\\ \\…
Jan Eerland
  • 9,244
  • 15
  • 25
7
votes
1 answer

How does a dead battery look in a circuit?

I'm working on a Kirchhoff's problem where two car batteries are connected in parallel. One is dead and one is good. It's a basic three variable problem where I'm working out the three different currents (I1/I2/I3) in the circuit when the switch is…
Chef Flambe
  • 1,071
  • 3
  • 12
  • 24
1
2 3
…
45 46