18 - Thevenin's Theorem - Concept with Solved Examples
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- เผยแพร่เมื่อ 10 ก.ค. 2024
- 18 - Thevenin's Theorem - Concept with Solved Examples #knust
In this video we are going to learn how to solve circuit problems using Thevenin's theorem.
Thevenin's theorem states that any linear circuit connected between two terminals can be replaced by a Thevenin's voltage Vth in series with a Thevenin's resistance Rth.
To find the current flowing in a resistor;
1. Remove the resistor you want to find the current through and mark the terminal
2. Find the Vth using KVL
3. Deactivate all independent sources, open circuit current sources and short circuit voltage sources and find the Rth
4. Produce the Thevenin's equivalent circuit and reconnect the resistor you removed.
5. Find the current through the resistor using the formula I = Vth/(Rth + Rl)
00:00 - Intro -
03:23 - Example 1
11:24 - Example 2
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Thank you so much sir! This is the only video that helped me understand the Thevenin's Theorem!
Wow. That's nice, you are most welcome. Where do you watch me from?
Thank you so much. The way I was so confused and finally you have relieved the stress I was having.👍🏾👍🏾👍🏾
Thank you so much Garba
Your explanation is very very easy to understand. Thank you very much.
Youre most welcome
You just made it so easy to understand, thank you very much
You are most welcome
Thank you so much!! Finally have understood Thevenins's Theorem
Wow. That's nice. What's your country of origin?
Kenya
@lizziemwesh7797 thanks so much. Extend my greetings to students in Kenya
You helped me a lot. Thanks!!
Thanks so much
Thanks my friend
thank you so much Sir, you are helping me a lot :)
Awww, youre welcome
Thank you so much for the great video
You are welcome
Excellent explanation. Thank you!
You are most welcome
Thank you😊. This was very helpful.
you are most welcome Debbie
would it matter if we were to choose to define vth as Va-Vb = 21 volts?
Irrezistable video , like it when you say rezista my man :D
Thanks so much
Thank you so much really helped
You are most welcome
i finally understand. tysm!!!
That's great
veerrrryyy helpfull:):):):):) thank you
Youre welcome
My African brother you have helped me so much. This video is the best I have found explaining the step by steps on how do this.
Thanks so much. What's your nationality?
@@SkanCityAcademy_SirJohn both my parents are from Sierra Leone but I’ve lived in England all my life.
Oh great, I see.
So are you in college or university?
@@SkanCityAcademy_SirJohn I go university in Southampton
Thank u very much
You're most welcome
amazing teacher man you are the best at explaining things
Aww thank you so much
Where do you watch me from?
@@SkanCityAcademy_SirJohn canada Ontario, yea I’m up pretty late 😭
Will you be comfortable texting me on WhatsApp +233243084034
@@SkanCityAcademy_SirJohn don’t have whatsapp, I have discord, skype, instagram, snapchat
in the first example, when the current of the final circuit turns out to be MINUS 3 ampere, doesnt it mean that the current has counter clockwise direction? or else put, when Vth is found negative, doesnt it mean that the positive and negative pole are reverse as initially assumed?
Exactly....
Thanks!
You are welcome
Love you man
Thanks so much
Nice explanation
Thanks so much
Great lesson sir. but i'm kin'of wondering as to why Vth is negative since the main source is the 35v
It doesn't really matter, the negative only means that that current is rather moving in the opposite direction to the direction we used.
Thanks boss 🙏
You are most welcome
one of the few videos that made me wish i can put two likes
Thanks so much
Just the best
Awww thanks so much Faith. I'm grateful.
🥹I now understand thanks Sir I pray midsem will go well 😁
Thanks for understanding. It will definitely go well. Good luck
Why do we need to assume there is a voltage source between points a and b in the the second example? In first glance I thought all the resistors are in series (5+10+5) because they have the same current
At glance, everyone will assume that the three resistors are in series but that's not true. You will need to think of plugging in a voltage source to see how current will be distributed in the circuit. Due to the presence of the node between 5 and 10, current will split. So no same current will flow throw all the three resistors
Nice video
Thanks so much Javed. Where do you watch from?
Helpful ☺️☺️☺️
Thank you
th-cam.com/video/w7a88ODjdV4/w-d-xo.html
Another great video sir...but why is it that in example 2, the 2A current is considered to keep circulating around 1 loop over and over
current produced by the 20v flows through both 10 and 5ohms and through the last 5ohms before it goes back to the source. meanwhile at the node where the 2nd 5 ohms is connected, current from 20v flows downwards while 2a flows upwards opposing eachother. now when you consider 2a to be circulating in that loop, it makes it easy to realize that it opposes the current produced by 20v in that branch
where do you watch from?
@@SkanCityAcademy_SirJohn I'm from Botswana sir 🇧🇼
Okay... That's fine. Hit me up on +233243084034 whatsapp
The second example when viewing the Vth towards the right side won't it be Vth+20 = 10(3/2) but I ended up having -5. Or I misunderstood something?
Direction of vth opposes 20v hence, vth - 20 = -10(1.5)
@@SkanCityAcademy_SirJohn as in moving from Vth anticlockwise through the 20V. I thought since the current will enter the negative terminal of the 20v it will be positive or? Like if we move anticlockwise from Vth the 20V will also be in anticlockwise.
Yes it will be positive as you say. But mind you current will leave negative terminal of vth making vth negative. Hence -vth + 20 = 10(1.5)
@@SkanCityAcademy_SirJohn oh ok thanks
So I'm assuming that the terminals of the Vth is kinda like in like with the terminals of the voltage source?
Once they are opposing each other the polarities will always change
Be careful with the units. You tend to forget those. You can’t just say: V = 5I + etc.
Because V is measured in volts, and I is measured in amps
in the second example can you please explain the I-2
well, good day, its very simple and easy to understand, consider the loop on the far left, the current in that loop will keep on circulating over and over. Now, the current produced by the 20v will flow throgh the 10, 5, and 5 ohms resistors. Since there is an open circuit, the current will not divide at the first loop where 10ohms, 5ohms and vth are connect, at the next node, the current wont divide but all will flow downwards in the 5ohm. notice that the two current values flowing in the 5ohms have opposite signs hence one should be negative. anyone of them can be negative, but the actual answer you get at the end proves the original direction of the current
Can you please explain why didnt 2A went only in 5Ω's direction and not to the voltage sources direction too?
the 20v produces its own current I, and according to conservation of energy, the same current produced by 20v should be the same current that returns to 20v, hence 2A is considered to bee circulating in that loop passing through only the 5ohm resistor
@@SkanCityAcademy_SirJohn thank you for explaining and how fast it was
@@erencelik049 you're most welcome
@@erencelik049 where do you watch me from?
@@SkanCityAcademy_SirJohn Turkey. But my lessons are in german taught
I have a question can i just use loop equation to find everything without using thevenin?
You you can. But once the question is specific, that using thevenin. Then you are restricted.
The loop equation is what? Mesh analysis?
@@danielpaulokpe365 kindly explain yourself well.
@@SkanCityAcademy_SirJohn what is loop equation ?
She asked if she could use it
@danielpaulokpe365 yeah, they are the mesh equations.
More explanation
Kindly check channel playlist for applied electricity, for more videos on this topic
shout out to you🤩
Thanks so so much ☺️
Why does the 2A current didn't split at that node
You can decide to split it, but the best way is to consider the voltage source as your reference source and use that to do current distribution. And that is what I did.
If we get 10 ohm vth?
Please come again with your question
how do you know what sign VTH is though? 15:35
You need to just look through the terminal to see which direction will be relevant to your calculation, then you decide.
Sir but how do you know on either to use clockwise or anti-clockwise for the first question when finding the Vth
10Q
100X better than organic chemistry tutor video
Wow☺️, thanks so much for your comment.
God bless you...I encounter same question yesterday in exam hmm I failed oooo
Same question?? Were you able to solve
@@SkanCityAcademy_SirJohn no because I wasn't on campus before and it dropped yesterday sir hmm I was confused rough
I love all your steps thanks very much
@EtseyAtsusuccess owww so sorry.
Which school do you attend?
@@SkanCityAcademy_SirJohn ACCRA TECHNICAL UNIVERSITY ATU
I=V/Rt=42/18 (12+6) how could be 18 ?These are parallel of seires?
I don't really get your question, but the most important thing is, because of the open circuit, there will be no current in 3 ohms, so the current in 12 and 6 is same, which means 12+6 is 18
Hence I = 42/18 = 21/9
Sir if you are going in anticlockwise that should be -6I not 6I
No please, notice that in the anti-clockwise direction, the current in 6 ohms is in line with the anti-clockwise direction hence it's supposed to be 6i not -6i. Please do you get it?
I really appreciate this video too but please from the second example why is the current passing through the 5 ohms resistor ( I-2 ) A. I'm alittle confused, what if it's rather (2-I )A. That's not the answer though but just to clear my thought and to get a better understanding why the current in the 5 ohms resistor is ( I-2 ) A
So first, we assign current I which flows through 10 and 5 ohms on top because there is an open terminal at ab so no current flows through that branch. The current I flows through the other 5 ohms on the left. Notice that the current source at the far left points downwards which means it's going to circulate in the 5 ohms in the anti-clockwise direction opposing the initial direction of I
@@SkanCityAcademy_SirJohn Thanks you're the best 😊👍🏼
Thanks so much
tu circuit lain bang tak sama dengan gambar
i don't understand how the 2A current only flows through the 5ohm resistor.
Kindly state the time in the video for easy reference
12:50@@SkanCityAcademy_SirJohn
@@SkanCityAcademy_SirJohn 12:50
It depends on how you assign current in the entire circuit. I took the current produced by the 20v as my reference, which means that 2A will just be circulating in the immediate loop. Meanwhile whichever way you do it, provided it's the best approach, you need to get the same answers
@@SkanCityAcademy_SirJohn cud u send me a link or name of a book that can explain briefly ur method
It feels Greek to me
Sir when current and path are in same direction so it will become -ve?
When current is in line with the direction you are taking it's positive
i hope ou realised the mistake you made at question 2 when you found the thevenin voltage to be positive 5
I've not seen any error. So if you have you should point it out
the answer to the first example is just 21 not -21
the answer is -21v or 21v depending on the direction you are working with. -21v and 21v are actually the same thing, the only difference is the polarity, where the positive terminal is on the right or the left.
@@SkanCityAcademy_SirJohn but didnt you take the voltage across the 6 ohm resistor in reverse the current is entring from pos polarity to the ground(i mean from above ) so the voltage should be reversed
the adds are too much bro
Okay, noted
Peeeezy