Node voltage method (steps 1 to 4) | Circuit analysis | Electrical engineering | Khan Academy
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The Node Voltage Method solves circuits with the minimum number of KCL equations. Steps 1 to 4 out of 5. Created by Willy McAllister.
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Electrical engineering on Khan Academy: A summary of the math and science preparation that will help you have the best experience with electrical engineering taught on Khan Academy. Become familiar with engineering numbers and notation, and learn about the two most important electrical quantities: current and voltage.
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Students might also find one (or more) of my videos helpful for Mesh and Nodal Analysis ..... I have videos for every aspect of electronics ...... but in circuit analysis Playlist I have videos for all the methods ..... supernode, supermesh, superposition, Thevenin, Norton, source transformation and etc. ..... sometimes it helps to watch several videos for the same topic to get a fuller understanding
Awesome video!!! Now I know everything !!! :D thx!
Hi sir. This is great content, for us a student it could help to understand the problem.
Thanks helped a lot , if you guys have time make more videos on electrical based lessons. Keep it up
You sir are a godsend. Thank you from all of us Circuits students out there!
Hi, this is great stuff. I was wondering if you offered a complete beginner to advanced electronics program?
Sir.. Your TH-cam channel is the best place to learn mathematics and physics.. Thank you sir
Thanks for the great video. I would have identified step one as finding the nodes first.
nice video help a lot thanks
nice video!!! informative
Hi, just a question: how would you identify the direction of the currents around the branch at 7:35 . Do you just assume?
ধন্যবাদ ভাইয়া ।
thanks to upload a good video. by the way, could you please tell me why the node on the left side of node 2 can't be a ground node? i thought the left node has same number of elements ( voltage source, resistance, current source).
Excellent! 😊
can anyone help me on y i2=v1/r2 since i2 is due to 15v and not coz of Is=3mA.
what is the definition of a node ? and based on what should I set directions of currents ?
very good
thq
9:10 why's it V1-V2/R1 instead of just V1/R1?
Because, if you consider the voltage coming from V1 and goes to V2 through the resistor R1, there should be a voltage drop at resistor R1. Therefore, you get this: V1-Voltage drop at R1=V2. So the drop voltage or the voltage across R1 resistor= V1-V2. Then if you follow the Ohm's law to determine the current flowing at R1 area that is I=Voltage across R1/R1; your equation becomes: (V1-V2.)/R1. You should note that, V1 is the node voltage that indicates the charge
@@mirza360 shouldn't that mean, according to what you wrote, that R2 also has a voltage drop across it, which it does if course, but why is that current calculation then not (V2-V3)/R2?
@@ChristianDybdahlXTR Actually, there will be no V3 as the connection is shorted toward the negative terminal.
@@mirza360 So could also say the equation IS (V2-V3)/R2 but V3 = 0
had the same question. Thanks to all the answers
In the most right of the figure, there is a blank wire. How is it following the middle wire? I am confused. I think there is a problem with the question.
nodal and mesh analysis selection criteria
my intuition would say, look at the amount of nodes you would have to give a name in the nodal analysis, and the amount of meshcurrents you'd have to define if you were to work with loop analysis. Use the one that takes the least calculations
What is the point of the reference node? What purpose does it serve. It is not like it actually acts as a benchmark/ground when writing the equations. The equations are the standard Kirchhoff's equations. I mean can someone explain the purpose of node voltage in general. Isn't it exactly like finding the current and etc the normal way through Kirchhoff's laws?
this video needs to be updated right this instant i refuse to stand for this
How do you know where the current arrows will point to?
Actually its CONVENTIONAL CURRENT which has a path from positive to negative.
Conventional Current or CC is a method for simplifying the basic Amperage concept. Also, CC is the thing which ammeters measure. In this case, please check out the battery or emf terminal's orientation. Although the flow of electron is from negative terminal to positive terminal, the conventional current is the reason behind calculating the flow of current from positive to negative :)
Thanks for the video! I'm stuck trying to figure out why i1 = (v1 - v2)/4kΩ. Please help me to understand.
Explain what you don't understand about it. Like why does the current of node 1 = voltage of node 1 - voltage of node 2 divided by 4k ohms?
Remember Ohms law?
Benjamin Dunn hi
ohms law. solving I=v/R.
i1 is the branch current flowing in the 4k𝛀 resistor. The direction that he drew for the arrow representing i1 on the diagram indicates that i1 flows from node 1 to node 2. Current always flows from high potential to low potential. That means that according to the current direction indicated on the diagram v1 > v2. Therefore the voltage drop across the 4k𝛀 resistor is given by v1 - v2. (The voltage at one end of the resistor is v1; and at the other is v2.) According to Ohm's law then (v1 - v2) = i1 x 4k𝛀. Solving that expression for i1 gives i1 = (v1 - v2)/4k𝛀. The directions of the branch currents as labeled in the diagram are completely arbitrary; however, if when you solve the KCL equations for v1 and v2 it turns out that v2 > v1 then that means that you chose the wrong direction for i1. (If you plug v1 & v2 into your equation for i1, you'll get a negative number. The minus sign indicates that i1 is flowing in the opposite direction from what you originally assumed.)
Why i1=(V1-V2)/4ohm
Why not consider the V on R2? For found i1?
Can you help me, please?
th-cam.com/channels/nQiktQpAYUHghfiF6WIQfg.html
there is voltage drop at the resistor R2 also. So shouldn't it be V2-V3/R2 instead of just V2/R2 ?
He does that, but V3=0V, because it's the reference node. So that makes it V2/R2.
Shubham Jain Detective L ....... I am Kira 😂😂😂
Can u explain why node voltage 1 equal 15
Amr Atef he just took it to explain us the problem
It’s trivial.
sir
I wrote it.
can i ask something? why i1= v1-v2/R1 not v2-v1/R1?
Because node 1 is on a higher potential than node 2. Node 1 is right after the positive terminal of the battery, and potential there is 15V, and when you move across R1, there is a voltage DROP, so potential at node 2 is less than 15V, so the difference in potentials (voltage drop on R1) is V1-V2
It is actually a matter of how the guy defined the direction of current. If the direction of current was defined as coming out of the node, then the voltage drop would be v2 - v1. Current (which is a flow of positive charge) flows from higher to lower voltage, always.
I don't get i1 in step 4
Why isn't it v1/r1
Timo m No. you must consider that V1 is the voltage BEFORE the resistor and that V2 the voltage AFTER. V1 and V2 are nodes.
Resistors have a voltage drop hence V1 a V2.
Why 'minus' Is at 8:24?
One year later: The currents into a node equal the currents out of the node. A more clear way to write it would be
i1 = i2 + Is
Since i1 is entering the node, and i2 + Is are leaving the node. That's how I like to look at it, hope it helps.
How is V1 a node?
Michael Heneghan it is not....
nodes are named in two types- simple (only 2) and principal (3 or more)
A junction between at least 2 element/components is a node
where's the next video
m.th-cam.com/video/LMC3jcNomNc/w-d-xo.html
why is V1 = 15volts even if V1 and Vs arent parallel?
because it is next to a voltage source of 15v and no components that could change it are between the source and that node!
@@brandonlovatt thank you!
Why dont you take 4Kohm as 4000 if you take 4, then will it not be like 4ohm.
the answer will be just in mA.
lol it was 2 years ago but being late is better than not coming at all.
What is the benefit of reference node this is not helpful
If u take it with only one node voltage V2 u will understand provided u give proper current direction
Hello fellow students from GMIT :))
i like ur video but ur too slow
shift + > .... you're welcome
why graze over the parts that are actually confusing? I am going to commit sewer side
nodal is a little more time
a lot of time is lost in painting the characters to write
A node is where 3 or more elements meet, you named nodes where only 2 meets.
he said 2 or more....
Burak Muhammetoğlu in the diagram , 3 is a node connected to 3 elements
haha "kurkov"? it's kirchhoff
haha it's кирхоф innit (in cyrillic it's read as 'kirhoff')
Not so helpful !!!!! DISAPPOINTED
Learn how to pronounce the word "components." I kept dwelling on that.