Electrical Engineering: Ch 8: RC & RL Circuits (13 of 43) Current=? in RL Circuit: Ex. 1
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- เผยแพร่เมื่อ 7 ก.ย. 2024
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In this video I will find the current through an inductor=? of a RL circuit with a voltage source.
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You saved my life 3 years ago and made me ace my mechanics exam. 3 years later, I am here because I have a signal processing exam, and you're saving my life once again. You, sir, are a legend! You symbolize success for me.
We are glad the videos are helping you with your studies.
This guy is literally the goat. There are so many examples too.
Thank You!
love & respect dear sir....
Thank you.
u made it look so simple... 😊
i should be sleeping now but i enjoy watching your videos :""))
Sleep is very important as well.
@Rustam Shahverdiyev
the current likes the easiest path so instead of 16 ohm it will flow by short circuit
When the circuit reaches steady state yes, but not until it does.
Professor Van Biezen, thank for all your helpful videos. Question for you, if you are trying to find the current i-4 (at resistor 4) and apply current division, don't you have to do it as follow. I x (4/4+12)? I see you put 12 in the numerator.
No, it is correct in the video.
because it is current division rule
Hey I am having trouble understanding why he used the ratio, do you think you can explain why?
Excellent teaching
Hello Professor Michel , why have you included the 16 ohms resistor when calculating the equivalent resistant at t > 0 and you didn't include when calculating the equaivalent resistance at t < 0 ??
At time t < 0, all of the current will pass through the inductor (since inductors do not oppose current when it is in a steady state) and essentially act as a short and no current will flow through the 16 ohm resistor. The moment the switch is opened, the inductor will oppose the current and some current will flow through the 16 ohm resistor.
Hi Sir,I find your lectures superhelpful.Thanks. Can you tell me what textbook are u following?
We use multiple sources as reference.
3:16 for t
5A would be possible if you had only 2ohm resistor. But it's connected in series with two parralel resistors. So the circuit's summary resistance is higher than 2 ohm, and thus it can't conduct 5A with 10v source.
I obtain also 3,75 A through the 4 ohms resistor
@@ionelmarianstefancu8170the other guy is correct lol I was in my 1st year in engineering and looking back I was very dumb as well 😅 I’m now an engineer and it’s funny to look back at old comments I made during school
Right, I make the calculus again with mesh method, and Yes is 1,5 A across the 4 ohms resistor. 🥵
Hello thanks I was requesting if possible teach me the use of the second method for looping in the same example thanks so much ......waiting to hear from. You
Are you not finding what you need in the videos?
@@MichelvanBiezen Thanks so much Professor I actually found it I really appreciate the time and concern
at t=0 isn't the inductor resisting? shouldn't the current passing through the inductor be zero at t=0? Thank you for the great videos. You are a lifesavor.
The switch OPENS at t = 0, thus the initial current through the inductor is indeed 1,5 A
Michel van Biezen doesn't the inductor act as a resistor as soon as the switch is closed? doesn't inductor appose current when there is a change in the current?
Just before t = 0, there is a steady state current flowing through the inductor. The inductor will not oppose a steady state current. Then the switch opens and the inductor will try to keep the current from reducing. But the current will reach 0 within 5 time constants.
Thanks sor. You are a gift from the god 😂
THANK YOUUUUUUUUUU SIR
thank you prof
You are welcome
So is it safe to say that at t>0 the current through the inductor will equal the initial current?
Only at t = 0+. The current will begin to diminish down to zero as t becomes larger.
excuse me sir or anyone who can see this but how do you start your ohm resistor equivalent? i always get this wrong this 2 and 12 are also in parallel right? and so is 2 and 4. where do I start with finding the R equivalent. it is driving me crazy.
You need to take it one step at a time. Before the switch is opened, all of the current will flow through the conductor and none through the 16 ohm resistor. (The branch with the 16 ohm resistor essentially becomes an open circuit). Then the 4 and 12 ohm resistor will be in parallel, so the equivalent resistance of those 2 will be 3 ohms ( 4 x 12) / (4 + 12) And then the 2 ohm resistor is in series to the equivalent 3 ohm resistor.
Using Thevenins and Norton’s is faster and easier imo. This is a great example though.
Dear Michel van Biezen, why 16ohm resistor becomes an open ?
Before the switch opens and the circuit is at steady state (current is not changing) then all the current will flow through the inductor and no current will flow through the 16 ohm resistor.
What about capacitance?
What does it mean when there is no initial stored energy?
Since there is a steady state condition before the switch opens at t = 0 sec, there is no opposition to the current due to the inductor and therefore there is no energy stored in the inductor.
Why isn't the 12 ohm resistor excluded too?
When the switch opens at t = 0 seconds, the left branch is no longer complete and no current can flow through that branch. But the other 3 branches including the one with the 12 ohm resitor are complete and current can and will flow through them.
Why do we exclude the 16 ohms resistor?
Before the switch opens the circuit is in a steady state condition. When there is no change in current through the inductor, there is no impedance, and therefore that branch acts like a short. All of the current will go through that branch instead of the branch with the 16 ohm resistor. So that branch acts like an open circuit.
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do independent sources shut down when t>0?
since that's when the switch is opened, then in a way, yeah.
Why doesn't the current flow through 16 Ohms?
Before t = 0 sec ( t < 0), the inductor does not oppose any current flow, so the inductor branch is essentially a short and therefore no current will flow through the 16 ohm resistor.
(An inductor only opposes a CHANGE in current).
prof. how much is voltage drop a cross each resistance?
The voltage drop across each resistor is the current through the resistor times its resistance. Since the current changes during the transient period the voltage will change accordingly.
you are graet
Sir why initially passes through the inductor?
Inductors only oppose current when the current changes. At steady state the inductor does not oppose current.
Michel van Biezen thank you very much sir.
how 16ohm is gone??
At steady state with the current flowing the inductor acts like a short and thus no current flows through the 16 ohm resistor.
Sir what is meant by steady state??
Usually when the source is first turned on, or the switch is closed or opened, there is a period (called the transient state) where the current changes. After a while the current no longer changes which is then called the steady state.
@@MichelvanBiezen So kind of u sir...u replied me within a day...I got the answer tnk u so much..
why is i0=i4 ?
The moment the swith opens the current trough the 4 ohm resistor and the inductor is 1.5 A.
I don't understand at 3:28 why i4 = 12/(4 + 12)?
That is a technique we use to calculate the current through parallel branches. The current in branch 1 = current at the junction x ( resistance in branch 2 / (resistance in branch 1 + resistance in branch 2))
Michel van Biezen Sir but we have resistance 2 with 10 v witch mean I0=5a
2024.01.19 감사합니다.
You are welcome.
This is natural or step ?
We are not sure what you were asking. At t = 0 sec, the switch is opened, but the source voltage is applied at all times.
@@MichelvanBiezen no I mean it is step response or natural....means charging of inductor and discharging of inductor show response while showing both differently is a transient so in this only charging then become itself a current source ie.inductor....so no in this case what type of response it should be ???
When the switch is opened, there will be a transient response due to the inductor, until steady state is reached.
@@MichelvanBiezen okay