Kirchhoff's Laws in Circuit Analysis - KVL and KCL Examples - Kirchhoff's Voltage Law & Current Law

Поділитися
Вставка
  • Опубліковано 18 гру 2024

КОМЕНТАРІ • 205

  • @johannes.50
    @johannes.50 Рік тому +28

    You made us understand what our teachers failed to do in 6 months

  • @MathAndScience
    @MathAndScience  11 років тому +5

    It doesn't matter at all. As long as you write the equations of the circuits consistently - applying the same rule for every voltage drop or rise - you will get exactly the same answer. It is common for different books and sources to use different convention for this. I use the one the makes the most sense for me and the one that is the most common for ENGINEERING. Physics sometimes likes to use the opposite convention as you pointed out.

  • @tavianwilkinson1
    @tavianwilkinson1 4 роки тому +5

    Lessons should just be like this where there is 1 great teacher per lesson who does a video like this for everyone to do its a lot cheaper than supporting schools

  • @tina4809
    @tina4809 7 років тому +8

    OMG THANKS TO YOU I ACTUALLY LEARNED SOMETHING IN THIS SUBJECT!!!! My lecturer doesn't know how to teach at all. U r a life saver 😍

  • @SpanishMule82
    @SpanishMule82 4 роки тому +12

    This video series is quite good. I'm taking circuit analysis classes and these videos are better than the lectures from my professor!

  • @Monsterenergy791
    @Monsterenergy791 11 років тому +7

    The world needs for teachers/professors like you. Great job

  • @garysellars8914
    @garysellars8914 10 років тому +55

    This guy's videos are excellent. He's a great teacher.

    • @wno1043
      @wno1043 6 років тому +1

      He's a great confuser. Better to learn the easy way. Why confuse people?

    • @amauryadams402
      @amauryadams402 4 роки тому +2

      ​@@wno1043 you have to know what your doing just go from basics then head on here it will make so much more sense

    • @johannes.50
      @johannes.50 Рік тому

      Who

  • @zeyad544
    @zeyad544 8 років тому +12

    My teacher needs to take lessons from you.

  • @321reh
    @321reh 11 років тому

    I'm a Electronic Engineering Technologist and I Like Yo Come Up With EASY Solutions To Problems Without unnecessary Loop Equations!! As Stated Before More Than 1 source Requires us to Pay Mr. Kirchoff a Visit!!! This is still A Great Video To Prepare You For More Complex Circuits

  • @bangkokhomes
    @bangkokhomes 8 років тому +5

    You are a very good teacher. The approach to the problem is very good.
    Thanks for that it helps a lot

  • @zain19
    @zain19 11 років тому +4

    You are right! 2 voltages add up to be 150. Once you solve for the parallel resistor,system will become a series circuit. The ratio equation is same as formula for i=v/r.In the series circuit, currents are always same. i=i is same as v1/r1=v2/r2

    • @richman61
      @richman61 3 роки тому

      yes that is different method of finding the answer. good job

  • @mitnavnvirkerikke
    @mitnavnvirkerikke 11 років тому +4

    Both the 'university physics' book and wikipedia says that the signs are opposite yours. According to those, the voltage law says: When you travel from - to +, then the emf is positive. When you travel from + to -, then the emf should be wrote negative. The same with resistors. If you travel from + to - with the current, then its negative, and the opposite.
    But it will give same answer, i think. Anyway, thanks for the video and the problem solving guide. Got exams next week. Great video again:)

    • @mohammedkhaled2456
      @mohammedkhaled2456 8 років тому

      I saw other teachers saying that from + to - there is a voltage drop so it must be - , and from - to + there is a voltage gain so it must be + . He is saying the opposite.

    • @MuzixMaker
      @MuzixMaker Рік тому

      It doesn’t matter as long as you’re consistent

  • @clintonberry8034
    @clintonberry8034 8 років тому +8

    Thank you. Im getting there slowly but surely

    • @wno1043
      @wno1043 6 років тому

      Find the equivalent resistance of the two in parallel, then find the total current flow of 25 A. Boom! Your almost done! 25A through a resistor that has a drop of 50 V across it gives you the answer. Done. As for Kirchoff's voltage law, the voltage drops around the loop will add up to the source voltage. That's all you need to know. It really doesn't matter which direction you go. From the positive, you have 50 V + 100 V = 150V (arriving at the negative terminal). From the negative terminal you have 100 V + 50 V = 150V (arriving at the positive terminal).

  • @mohammedkhaled2456
    @mohammedkhaled2456 8 років тому +3

    from negetive to positive there is a potential gain so it must be positive not negetive as you said

  • @NelsonGomez-do5gp
    @NelsonGomez-do5gp 2 роки тому

    This teacher makes the problem become something easy since the difficulty becomes something very simple.

  • @nigelgreen8186
    @nigelgreen8186 6 років тому +3

    It does not matter which convention you use for the sign of the current as long as you are consistent, you will get the right answer either way. It does not matter that there is another way to solve this, even if you think it is an easier method, this lesson is about using KVL and KCL and imparting that skill ready for use in other cases where it is much more complex. Neither is the time he spends on the algebra manipulation wasted. Who knows just what the viewer is capable of, or not. He does not have a live audience to signal to him that they do or do not understand. A skilled teacher can tell by the reactions of the class.

  • @conraddzetu6090
    @conraddzetu6090 10 років тому +9

    Thank you sir, I really appreciate this teaching

  • @ledevergreenemma2645
    @ledevergreenemma2645 4 роки тому +2

    Excellent! simple and easy to understand. Thank you!

  • @ninjanapkingaming8419
    @ninjanapkingaming8419 4 роки тому +1

    I love how this guy explains everything, I learn a lot from him I'm only in eighth grade and I even know about Quantum physics from him thanks for your help.

    • @epochseven4197
      @epochseven4197 3 роки тому

      You're lucky to have UA-cam and videos like these while still in school. All I had was a heavy textbook and a professor who just confused us more. (If I had access to these videos back in my time, maybe I wouldn't get scared away from engineering lol.)
      Definitely take advantage of these videos!

    • @vedikamadhesiya6719
      @vedikamadhesiya6719 2 роки тому

      @@epochseven4197 same here

    • @johannes.50
      @johannes.50 Рік тому

      ​@@epochseven4197 o

  • @instaminox
    @instaminox 8 років тому +2

    I encourage you guys to buy his DVD series he makes things easier to grasp :)

  • @kellytownsend4526
    @kellytownsend4526 3 роки тому

    Was struggling to understand the Loop Law for a Lab assignment, Thank you!

  • @jeanpaulvautour3776
    @jeanpaulvautour3776 3 роки тому +1

    You are the best teacher thank you so much

  • @ALMALAWI
    @ALMALAWI 10 років тому +2

    THANKS . YOU HIT THE GOALS EASILY...

  • @Tropod8
    @Tropod8 11 років тому

    You are so much better than my EE98 Professor at SJSU... I wish you were the prof...

  • @dublevijgaming8058
    @dublevijgaming8058 6 років тому

    when im looking for a tutorial then i see this guys automatic this is very niceeee!

  • @sweatstallion8437
    @sweatstallion8437 3 місяці тому

    Im in my second half of my junior year of Electrical Engineering. I just now realized on this day that KVL is essentially ohms laws over and over again !

  • @millguerra3570
    @millguerra3570 Рік тому

    You are changing me current law since l know that when a current flow out of a junction is negative and the one that flows in is positive, but it is a new chalange now.

  • @Giggles_iJest
    @Giggles_iJest Рік тому +1

    Thank you! Sincerely!

  • @devjyarn
    @devjyarn 4 роки тому +1

    Thanks so much for hosting these. It's such a valuable resource, given that online courses in 2020 are kind of crap.

  • @divyangvaidya1999
    @divyangvaidya1999 2 роки тому

    A question: At 10:43, shouldn't I1 be positive because it is going inside the node and I2 be negative because it is exiting the node?

  • @emaduddin1212
    @emaduddin1212 9 років тому +3

    I understood the way you explained.
    Thank you!

  • @brianthompson7174
    @brianthompson7174 10 років тому

    Excellent Job. Very thorough. Enjoy all the videos!

  • @markkennedy9767
    @markkennedy9767 Рік тому

    Can you comment on what the choice of loops should be in a given circuit generally. Should no loop be the combination of any of the other loops chosen. For example, would choosing the outer loop also here just yield the same information as the two inner loops.
    Also, can you give any intuition whether Kirchoff rules always lead to a solution: ie that we always get as many independent equations as variables. Thanks.

  • @vwsandvettes3253
    @vwsandvettes3253 4 роки тому

    Thank you for this video. You are an excellent, relatable instructor and your teaching style is just what I think a lot of us need. This is an excellent refresher of training I had 30+ years ago in tech school in the USAF.

  • @danielmitch871
    @danielmitch871 4 роки тому

    Thanks for your service......dan

  • @akshaerioishwarlall8072
    @akshaerioishwarlall8072 3 роки тому

    This guy is amazing!! Does he still upload ??

  • @SindisiweSithole-ep2dc
    @SindisiweSithole-ep2dc Рік тому

    Thank you sir I appreciate your time ❤

  • @hassegreiner9675
    @hassegreiner9675 5 років тому +2

    It's good intro to Kirchoff which is essential when the circuits get more complex, but for the example it's simpler to find the reciprocate of the two parallel conductivities (1/(0,05+0,2))=4 Ohms and divide that into the given 100V which gives you current through the unknown resistor of 25A, and since the voltage drop is given as 50, the resistor is 2 Ohms.

  • @Mr.M1STER
    @Mr.M1STER 7 років тому +2

    What you did here confused me. What I did was say we know the voltage across r2 and we know it is 20 ohms, so the current through that resistor is V/R, 100/20 = 5 A. The voltages across resistors in a parallel section are the same so the voltage across r3 is 100V. We know r3 is 5 ohms so, V/R, 100/5 = 20A. Now, the sum of currents through a parallel section must equal the total current in the circuit so 5A+20A = 25A. From the start we are given that the voltage across r2 is 100V and we know that the voltage across r3 is also 100V. Vs is 150V so the voltage across r1 must be 50V. R= V/I and we know the current through r1 must be the total current, 25A and the Voltage across r1 is 50V... 50/25 = 2 Ohms.

    • @wno1043
      @wno1043 6 років тому

      He confused me too! He really made it complicated! Why? It's so easy to understand without all that formula writing and re-writing.
      After I got out of the Navy, i took some additional electronics. I spent many years after as a bench tech, then a field service tech, finally ending up in marketing and sales for an oceanographic instruments company.

  • @abusudais90
    @abusudais90 10 років тому +4

    Current flowing into a node has a positive value not negative while current leaving a node is written as negative .So KCL @ top node should it not be i1 - i2 - i3 =0???

    • @MathAndScience
      @MathAndScience  10 років тому +9

      You get the same equation either way. Typically, the convention is how I have it in the video for engineering students. You can use the opposite convention and you will get the exact same node equations.

    • @abusudais90
      @abusudais90 10 років тому +1

      mathtutordvd Oh I see ,I got a little bit confused ,many thanks for the explaining.:)

  • @amradel7664
    @amradel7664 2 місяці тому

    Thank you for this lesson you are awesome

  • @wandereview
    @wandereview 11 років тому

    Thank you, you have explained everything clear and concise.

  • @davidchang5862
    @davidchang5862 11 місяців тому

    With UA-cam and all the other great social media platforms around, schools will soon become artifacts in the museums. 😮

  • @s.hara_o7661
    @s.hara_o7661 4 роки тому

    learning this over quarantine

  • @sidstam
    @sidstam 11 років тому

    Nicely and methodically explained.

  • @japotillor
    @japotillor 10 років тому +1

    Good job, though it would be easier to make an equivalent series circuit in my opinion. I teach the opposite convention of what you teach in the video, but since you used the same convention throughout it works just fine. Good presentation

    • @MathAndScience
      @MathAndScience  10 років тому +4

      Thanks Joe, yes this circuit is simple and can be solved much faster by using equivalent resistance, as you indicated. But, the point here is to understand Kirchhoff's laws. Its easier to understand those if you start with simpler circuits which is what I have done here. Also, the sign convention that I used is the one used in most engineering textbooks. You can of course use the opposite convention as it doesn't really matter - you will get the same answer. Thanks!
      Jason

    • @japotillor
      @japotillor 10 років тому +1

      Yep very true, if my students have trouble ill send them to this channel

  • @krantikoganti
    @krantikoganti 3 роки тому

    If I would have come across this Tutor when I was In school. I would have been an Electronics and Communication engineerc instead of IT professional

  • @jib9058
    @jib9058 8 років тому

    sir is there any priority between kvl and kcl ? i mean when you are writting the equation kvl should be first or kcl .thank you

  • @MrAngbarako
    @MrAngbarako 10 років тому +2

    Thank You Sir, Great Help!

  • @puchiko19939393
    @puchiko19939393 9 років тому

    Clear explaination😄helps me a lot

  • @tresajessygeorge210
    @tresajessygeorge210 Рік тому

    THANK YOU... SIR...!!!

  • @senorverde09
    @senorverde09 4 роки тому

    The majority of viewers pretty much agree to use an equivalent resistor value to find R. Although useful for this simple circuit, you'll find knowing KCL/KVL comes in handy when dealing with far more complex circuits especially those with multiple voltage sources.

  • @ihssanabourshaid1088
    @ihssanabourshaid1088 4 роки тому

    thank you ,you just saved me

  • @omega6872
    @omega6872 7 років тому

    One of the best !

  • @vishalmishra3046
    @vishalmishra3046 4 роки тому +1

    Here is something simpler with few equations and no new variables: 20 ohm & 5 ohm in parallel are equivalent to (20x5)/(20+5) = 4 ohm. Total current = 150/(R+4) = 100/20 + 100/5 => R+4 = 150/25 = 6, So, R = 2 ohms.

    • @MathAndScience
      @MathAndScience  4 роки тому +2

      Hi yes of course you could solve it that way, but that’s not the point. The point is to learn kirchhoff’s laws so you can use this method to solve more difficult circuits. Jason

  • @ddino2549
    @ddino2549 11 років тому +2

    Perfect, thank you!

  • @katebalbalawi890
    @katebalbalawi890 7 років тому

    excellent explanation

  • @baguettebaguetteneverforge1758
    @baguettebaguetteneverforge1758 4 роки тому

    Thank you That made so much sense

  • @altheamendoza3329
    @altheamendoza3329 3 роки тому

    why negative for i1, when it’s gaining? is it not a positive?

  • @dels323
    @dels323 11 років тому

    very well explained, great job!

  • @johnmichaelpatena6056
    @johnmichaelpatena6056 8 років тому

    We had an assignment to be solved using KCL and KVL but our instructor failed us coz she said that we used mesh analysis. Now, I don't see the difference between the two. Would you please explain? thanks a lot

  • @AmericaFirstFree
    @AmericaFirstFree 10 років тому

    Amazing job

  • @SweRaider1993
    @SweRaider1993 10 років тому +6

    emil lagman That's not the point. It's demonstrating a concept that can be applied to more complicated circuits.

    • @MathAndScience
      @MathAndScience  10 років тому +7

      Absolutely. I chose to illustrate these concepts using a simpler circuit. But later you will have to apply these concepts to more complex circuits that you can't do by inspection. Thanks again. Jason

  • @mattevers632
    @mattevers632 2 роки тому

    Thanks you teacher

  • @malkiatsingh3297
    @malkiatsingh3297 7 місяців тому

    Thanks so much

  • @marciaadime2631
    @marciaadime2631 3 роки тому

    Sir could you please help me with all the equations of Kirchhoff’s law in a closed circuit

  • @balikawasu
    @balikawasu 9 років тому +1

    Thanks ,i learned alot:)

  • @Vrinda219
    @Vrinda219 2 роки тому +1

    Thanks sir

  • @WINCHOism
    @WINCHOism 9 років тому

    So this is kind of like mesh analysis?

  • @SweRaider1993
    @SweRaider1993 10 років тому

    mitnavnvirkerikke It doesn't really matter because we're talking about electrical potentials which can be defined either way just like you choose yourself when solving other physics problems with coordinate systems e.g. what direction should be positive or negative.

  • @dahamahmed778
    @dahamahmed778 8 років тому

    thank you very much it was really helpful.

  • @ShamanRing
    @ShamanRing 8 років тому

    another way to do it is combine 20||5 and you get 4 ohm. You know its 100v on V4 because it was given. That means R has to be 50 V (rest of the power supply) Do a KVl and you will get -150+I1R1+4I1=0 . What do you know? I1R1=50V. 4I1=100V and I1=25 A. R=V/I => 50/25 = 2 ohm

  • @321reh
    @321reh 11 років тому +1

    Simplify this Circuit down to a equivalent Series Circuit!!! The equiv 20 ohm in parallel with 5 ohms equals 4 ohm ( Rt=R1xR2/R1+R2)=100/5=4 ohms We know R unknown drops 50 volts(150-100=50volts) Set up a RATIO EQUATION R/Vr =R/Vr,,,,,,,R/50 = 4/100.....100R=200 therefore R=2 ohms.....No Need To write all these loop Equations Unless You have more than 2 or more Current or Voltage sources That's what My Engineering Technology Teacher told ME!!(Who Happens to be a ELECTRICAL ENGINEER!!!)

  • @wessee427
    @wessee427 11 років тому

    is it not easier to divide to get the total current going through 20 and 5 with same voltage of 100 then divide 150 over that number and you will get total resistance and just get the difference between that and the parralle resistance (20 and 5)??? final answer is 2

  • @lifestyle_and_life_lessons
    @lifestyle_and_life_lessons 2 роки тому

    awesome but how the negative affects the values I don't get that

  • @incudust953
    @incudust953 3 роки тому

    why does my schaums basic electricity book state that if voltage flows negative to positive its a positive voltage, and u say its a negative voltage

  • @TheArt832
    @TheArt832 10 років тому

    it just take 30 sec :) Req= 20//5 = 4 ohm V=150V Vr=100V Vr=(Req/R+4)*V => 100=(4/R+4)*150 => R=2 Ohm

  • @zektr2411
    @zektr2411 Місяць тому

    thank you

  • @bashashaik2991
    @bashashaik2991 5 років тому

    Thank you sir

  • @syedahmed1731
    @syedahmed1731 7 років тому

    Ur Amazing..... thank you

    • @MathAndScience
      @MathAndScience  7 років тому

      So happy you liked it!
      Get our Free App and View all Lessons!
      www.MathTutorApp.com

  • @infantadarsh440
    @infantadarsh440 7 років тому

    Thank you sir..!

    • @MathAndScience
      @MathAndScience  7 років тому

      I really appreciate it!
      Get our Free App and View all Lessons!
      www.MathTutorApp.com

  • @irabu9991
    @irabu9991 7 років тому

    lol i dont understand a lick of this and I solved for i1 just by using common sense lol... im so lost :)
    thanks for the soft serve on KVL and KCL though, really helps

  • @Lolleittaadam
    @Lolleittaadam 10 років тому

    really nice topic
    ..............Iunderstand well

  • @NelsonGomez-do5gp
    @NelsonGomez-do5gp 2 роки тому

    an equation with a high degree of difficulty is converted into an easy solution

  • @dabadiribabulcha8161
    @dabadiribabulcha8161 7 років тому

    how we takeposive negative from our circuit?

  • @orjiemmanuel6442
    @orjiemmanuel6442 2 роки тому

  • @larrycrain5650
    @larrycrain5650 5 років тому

    I was following along fairly well until, when analyzing the right part, you converted a passive resistor into an active source - this completely threw me. In the actual circuit the voltage at the + of the 5 ohm resistor must be > 100 volts else the value of the other resistor can be calculated. If the voltage at 5 ohm resistor is > 100 then the current flow is not correct when calculated using 100V???

    • @faizmalik9210
      @faizmalik9210 4 роки тому

      A perfect example of the danger of a handwaving argument.

  • @edericoreichard1990
    @edericoreichard1990 4 роки тому

    Is this part 4 to your presentation?

  • @alexandruarchip3382
    @alexandruarchip3382 4 роки тому

    Hey sir,i have a problem with my payments on your site and blocked my ip on the specific site,can you help me please,i really want to study them :)

    • @MathAndScience
      @MathAndScience  4 роки тому

      Hi, please email jason.mathtutor@gmail.com and we will get everything going for you.

    • @alexandruarchip3382
      @alexandruarchip3382 4 роки тому

      @@MathAndScience already did,gracias :)

    • @MathAndScience
      @MathAndScience  4 роки тому

      Ok great I see it. I sent that to my office manager who will reach out to you later today. Thanks! Jason

  • @AartiSharma-gy9jt
    @AartiSharma-gy9jt 6 років тому

    Sir how to know apply kcl ya kvl please give me answer

  • @syedinamullahshah6076
    @syedinamullahshah6076 6 років тому

    Why kcl is not applied on series circuit and kcl on parallel circuit

  • @tommoore8209
    @tommoore8209 3 роки тому

    I thought all components in parallel have equal voltage, i.e. all components in your diagram will be 150V?

    • @MathAndScience
      @MathAndScience  3 роки тому +2

      The two resistors on the right are in parallel but they aren’t in parallel with the resistor on top. They are in series with that one. So the two resistors on the right will have the same voltage across them but it won’t be 150V. The resistor on top prevents the resistors in parallel on right from seeing the full source voltage.

    • @tommoore8209
      @tommoore8209 3 роки тому +1

      @@MathAndScience Perfect I see, thank you for replying to my comment and clearing that up for me. Your videos are great and you are amazing at teaching.

  • @quincejohnsjr.9431
    @quincejohnsjr.9431 3 роки тому +1

    No need for kvl we know from the beginning that i1 = i2+i3

  • @bashashaik2991
    @bashashaik2991 5 років тому

    More problems sir...upon sies pallel

  • @sheshab
    @sheshab 11 років тому +1

    14:27 ? c'mon it took me 30 seconds to solve it :D anyways thanks 4 the video :D

  • @adammoe537
    @adammoe537 4 роки тому +1

    why are you making it hard? Just parallel the 5-ohm resistor with a 20-ohm resistor and that is=4. then you can find the current there which is 100/4=25 and we know the current will be same at the R since they connected in series, therefore, -150+25R+100=0 so R=50/25=2 ohm

    • @MathAndScience
      @MathAndScience  4 роки тому +3

      You’re missing the point. The point here is to solve this simple circuit using Kirchhoff laws, so that you can use this more powerful method for more complex circuits.

    • @epochseven4197
      @epochseven4197 3 роки тому +1

      In a timed exam environment, I agree that your method is more efficient. He purposely made this example "hard" so we can understand the concepts of Kirchhoff's Laws (KCL and KVL).

  • @deslomeslager
    @deslomeslager 11 років тому +12

    I don't get it. it took me 5 seconds watching only the circuit to see it would be 2 ohm. because? 100 Volts over a 20 Ohm gives 5 Amp, 100 Volt (as they are parallel) over a 5 ohm gives 20 Amp. Both currents run through R, which has the remaining 50 Volts. R = U / I = 50 / 25 = 2 Amp. A (!) simple example I guess.

    • @WhoWantsToKnow81
      @WhoWantsToKnow81 11 років тому +9

      Sure, that is one way to solve it. But the prof solves it using KCL and KVL, which is a different approach entirely.

    • @happyliferay
      @happyliferay 10 років тому +7

      you think you are smart or something? this is a tutorial on Kirchhoff’s Rules. i think anyone who has basic knowledge will know the answer in 5 seconds using simple ohms law

    • @deslomeslager
      @deslomeslager 10 років тому +1

      And that is the idea of my comment. There is no challenge to use a calculation on a simple circuit. A difficult circuit would get our minds working, just wanting to solve it. It is not about being smart, but about teaching our brains to the most possible extend. Your view on the matter is -as good- as mine. No offense meant.

    • @ArthurSperotto
      @ArthurSperotto 7 років тому +6

      Whoa we got a badass over here.

    • @wno1043
      @wno1043 6 років тому

      Exactly. I don't know what he's trying to prove. Guess he likes to confuse people. I learned electronics in the Navy electronics school at Treasure Island in the 60's. We learned the easy way. We never would have gone through all that. But we did learn Kirchoff's laws as well.

  • @noxin86
    @noxin86 9 років тому

    Why move the 50 over at the end??
    Even if you move it over why is it not still -50
    You just stated the final answer is 2 ohems why is it??
    What equation did you do to get 2ohmes ?

  • @aram5642
    @aram5642 Рік тому

    Honestly I knew how to go about solving this, but if I were to solve it on my own I would have definitely screwed up those plus/minus and directions.

  • @naj9745
    @naj9745 11 років тому

    Thank u