Resistors in series | Circuits | Physics | Khan Academy

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  • Опубліковано 23 тра 2008
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    Resistors that come one after another. Created by Sal Khan.
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КОМЕНТАРІ • 277

  • @Kai-Xi
    @Kai-Xi 10 років тому +278

    0:48 "If there is any such thing as reality" XD

    • @panchvangapandu5349
      @panchvangapandu5349 9 років тому +15

      Derpy Hooves lol, Khan Academy getting philosophical...

    • @MrSocialish
      @MrSocialish 6 років тому +15

      LMAO i just came from the khan academy website to the UA-cam video just to make the comment you just said!
      Khan is more than a person. He is an omniscient force.

    • @bryllethe13
      @bryllethe13 4 роки тому

      hahahahahaa

    • @hassanhamze_14
      @hassanhamze_14 3 роки тому

      Are you guys alive in 2021

    • @AnaOhKay
      @AnaOhKay 2 місяці тому +1

      @@hassanhamze_14 are *you* alive in 2024?

  • @vishnureddy3977
    @vishnureddy3977 9 років тому +263

    "My wife will probably mind that I didn't answer" LOL

  • @MrManwookie
    @MrManwookie 10 років тому +96

    "If there is any such thing as reality"
    Sal's having another existential crisis :P

  • @khanacademy
    @khanacademy  15 років тому +50

    Real-world wires have resistance, but in the diagrams, we assume that the non-resistor part of the circuits have no resistance (or that it has all been added to the "resistance" in the diagram)

  • @midnightsilverpuppy
    @midnightsilverpuppy 7 років тому +30

    "For fun let's put in a third resistor"
    Me: "whoa! U wild"

  • @biotch77
    @biotch77 11 років тому +21

    "but what we know in reality what is happening, if there is such a thing as reality..."
    sal, you're awesome.

  • @lucasgdrezes
    @lucasgdrezes 8 років тому +178

    I don't wanna be an electrical engineer, I just wanna got some questions right on the test I'm having tomorrow.

    • @DonJuliusss
      @DonJuliusss 5 років тому

      RT

    • @gomugomutree6075
      @gomugomutree6075 3 роки тому +1

      i hope you did well on your test

    • @hey9530
      @hey9530 3 роки тому +2

      Five YEars Later -> How'd u do on the test?

    • @lucasgdrezes
      @lucasgdrezes 2 роки тому +2

      @@hey9530 Well, I graduated high school without any problems. The video was helpful!

    • @lucasgdrezes
      @lucasgdrezes 2 роки тому +1

      @just some guy tired of life Yessir.

  • @cierrapresson4163
    @cierrapresson4163 8 років тому +55

    I love that Sal managed to slip in a little philosophy while he was at it.

  • @genchani8537
    @genchani8537 10 років тому +50

    OMG this is so simple. When my professor explained this part it sounded so damn hard. I wish you were my professor :)
    Btw, thanks a lot for these videos.

  • @ernestosaboia
    @ernestosaboia 6 років тому +12

    4:58 Hey Sal, thanks for all your teaching and sharing, so here is my small contribution: Electricity in a wire moves at 2/3 of speed of light, electrons move very slow :)

  • @Becca11Dance
    @Becca11Dance 12 років тому +10

    His voice is so relaxing :)

  • @skarpengland
    @skarpengland 8 років тому +24

    So, i used Khan academy all last year when i did my basic introductory course in medicine. now, i am doing physics and chemistry to hopefully enter medical school...
    and didnt you know, Khan can help you in physics as well!
    THANKS!

    • @fadyfarouk8635
      @fadyfarouk8635 7 років тому

      good luck!

    • @skarpengland
      @skarpengland 7 років тому +7

      i got accepted! i also got exactly the stuff in this video, in my physics exam. talk about coincidence

    • @fadyfarouk8635
      @fadyfarouk8635 7 років тому

      ***** wow good job, I hope I get accepted too. Have a great college period!

  • @Hiandbye95
    @Hiandbye95 12 років тому +8

    I think the amazing thing about your videos is that I understand everything you explain.
    This is something I rarely experience in school. xD

  • @kschwab14
    @kschwab14 12 років тому +19

    "It's my wife, she'll probably mind that i didn't answer but anyway...."
    haha love the dedication

  • @reezis1619
    @reezis1619 7 років тому +3

    After watching 6 minutes of the video I just wanted to say that you are AMAZING at explaining things. You make everything so easy to comprehend

  • @jaydaappleton6463
    @jaydaappleton6463 3 роки тому +1

    He is such a good teacher. I literally came here knowing nothing about circuits, and after watching this video I somehow am completely ready to complete my lab work. Now the work suddenly seems so easy.

  • @seanki98
    @seanki98 8 років тому +54

    0:48 deep

  • @sethboston6356
    @sethboston6356 7 років тому

    You really have a way with teaching, as I am sure you have been told many times before. Thank you

  • @vomitingteddy
    @vomitingteddy 9 років тому +28

    should have answered the phone man

  • @brianhartmann5972
    @brianhartmann5972 10 років тому +1

    Kahn academy is very helpful, in fact I watched this video to clarify some my knowledge on circuits because my physics teacher was unclear. However, in a battery, the electrons do in fact flow from the end known as "positive". This may be confusing at first but the reason that it is denoted this way is because that is the side with the higher electric potential energy (the side with all of the electrons, so it actually does flow from the positive end to the negative end). Other than that, this was a great video. I just wanted to clarify

  • @NoahA211
    @NoahA211 12 років тому

    I would honestly rather listen to these videos and just go to class on test days than having to sit through mundane class after mundane class...learning nothing. You are a life saver Khan!

  • @poonamjoshi1101
    @poonamjoshi1101 4 роки тому +1

    Man! Whoa Sal! 'If there is anything such as reality'-words of a legend (going through an existential crisis)

  • @gh-rb7bb
    @gh-rb7bb 8 років тому +8

    thanks man I wish u were my physics teacher

  • @aumgandhewar3114
    @aumgandhewar3114 2 роки тому +1

    I love how y'all maintain retention by being friendly and sometimes amusing

  • @Mrs_Potential
    @Mrs_Potential 5 років тому +3

    thank you very much. i totally have a different view on physics. its actually easier and more sensible than i thought. thank you

  • @mitch3850
    @mitch3850 11 років тому +2

    Sal is the man.
    I attend university in Victoria, Australia, and one of my classes is Electrical Systems.
    The lecturers are very smart but they forget that many students haven't dealt with the basic concepts of electrical functions, and tend to skip over them.
    I'm 12 weeks in and about to sit my exam, and before seeing these videos I was really worried. But SAL MAKES IT SO F***ING CLEAR.
    If I get a pass, it's due to Sal and Khan. Thanks man!

  • @tristanisgangsa
    @tristanisgangsa 12 років тому +4

    THANK YOU FOR THE CLOSED CAPTIONS! :D It's great for hearing loss and to check if you miss something! :D

  • @aniquanausheen7798
    @aniquanausheen7798 7 років тому +3

    i like this khan academy..
    its awesome.

  • @Daski69
    @Daski69 12 років тому +1

    I'd like to initiate this comment with a huge THANKS to you Mr Khan, you're a genius!
    Second, I'd like to contribute with a personal idea, to people who have a hard time with understanding some basics when it comes to circuits, like I used to have.
    Why is it so that the voltage over the "more powerful" resistor is higher than the other. Well, voltage is defined as energy/charge. It requires more energy to get pass the big resistor than the small, simple. Over and out.

  • @DrLasker1
    @DrLasker1 13 років тому

    thanks again sal! you mentioned a lot of small but important details which my physics teacher didn't mention (or perhaps I missed them because I was sleeping =), which really helped me understand this better! thanks!

  • @madhusai220
    @madhusai220 6 років тому +8

    0:48, from that moment to this moment, i'm living in existential depression...

  • @Ray-tf2ps
    @Ray-tf2ps 5 років тому +2

    "when resistors in series we just add them up" YOU COULD'VE SAID THAT AT THE BEGINNING. But the explanation did help fix my curiosity

  • @Alapozo
    @Alapozo 8 років тому

    This was a very good video!!! Great explanations

  • @TimWhiteNC
    @TimWhiteNC 11 років тому +1

    Sal is the Bob Ross of Science.

  • @Fmiguelify
    @Fmiguelify 12 років тому

    Thankj you, this video is really good, i undestand more about the series Circut now, and about the Volt Drops on the eacht resisters.

  • @jorgediaz549
    @jorgediaz549 11 років тому

    I love this guy! circuits + comedy = priceless

  • @techmaster90
    @techmaster90 5 років тому

    This is great thank you!

  • @hiyabalemayehu3443
    @hiyabalemayehu3443 4 роки тому +1

    I know you guys think this guy is the best teacher but what I'm about to say is different
    THIS GUY JUST EXPLAINED THIS TO ME PERFECTLY, SOMETHING MY TEACHER COULDNT DO FOR A MONTH.

  • @danoconnor4452
    @danoconnor4452 5 років тому

    I know this is 12 years old so you’re probably not going to read this, but what helps me understand that the current is constant is to think of electrons as cars and the circuit as the road. At each “resistor” in the road, the speed limit decreases by a certain amount. So the bottleneck of electrons is analogous to bad traffic. The main difference is that electrons don’t “travel” along the wire like a car travels on the road; meaning that the instant you turn on the circuit, the current is constant. You don’t have to wait for the electrons to “travel” to each resistor, creating a bottleneck and then having it slow all the previous electrons down (which is what happens in traffic).

  • @ScottLahteine
    @ScottLahteine 10 років тому +1

    I'm just starting on this path with electronics, so naturally I count on Khan to set me straight. But this is a little confusing as laid out. First, sure, label the battery output terminal + (as in, adding electrons here) but perhaps denote that the + terminal is negatively charged (neg.) because electrons are negatively charged. And just don't label the other terminal.
    Second, as I understand it resistors convert electrons into heat and radiate, so electrons are actually being spent by the circuit, and that is why the current drops. Correct me if I misunderstand this.
    Also, correct me if I'm wrong that: The potential difference (voltage) is the same across the entire series circuit, only the load is dropping, and smart DC power supplies will only feed the required amperes (for the given voltage) to power the circuit.

  • @kabascoolr
    @kabascoolr 11 років тому +1

    Lol I didn't know that he made videos on circuits. These, especially Kirchhoff's Laws really kicked my behind last semester. It's mostly because our professor was under the assumption that we knew circuits well before entering his class. I did but I'd forgotten most of the things.

  • @WalkAbout28
    @WalkAbout28 7 років тому

    Sal has taught me math through calculus, organic chemistry, and now physics

  • @BaronMorte
    @BaronMorte 14 років тому

    Sal,you are the man. Thank you.

  • @dinoLomedico
    @dinoLomedico 13 років тому

    This gentleman is an excellent teacher !!!

  • @comedian619
    @comedian619 11 років тому

    Very Helpful.Thank you

  • @GENEis1Wascally
    @GENEis1Wascally 14 років тому

    I liked the video. He is a very good instructor!

  • @rtsjoe
    @rtsjoe 14 років тому

    I love it how he pauses to think how to put things in layman's terms.

  • @landenwolever1016
    @landenwolever1016 7 років тому

    is the voltage constant throughout the circuit or is there a different voltage at two given points around each resistor?

  • @chainheart3
    @chainheart3 11 років тому

    tanks! this video is awesome!

  • @NitishChauhan1
    @NitishChauhan1 11 років тому +1

    "if there's any such thing as reality" i've never seen a prof. get more specific when setting a premise.

  • @Tuanski
    @Tuanski 9 років тому +31

    I have a new religion called "Salmankhanism"

  • @hageraliart
    @hageraliart 3 роки тому +1

    Could someone please tell me what exactly causes the potential drop when charges across a resistors?

  • @KarishmaGReddy
    @KarishmaGReddy 16 років тому

    great video!! thanks so much

  • @SanFranLOVER1972
    @SanFranLOVER1972 12 років тому

    I love you. Seriously. MUCHO LOVE FROM GEORGIA IS BEING SENT YOUR WAAAAAAAAAAAAY!

  • @Hax04r
    @Hax04r 10 років тому

    @jaskaransingh because the battery is separated in a cathode(negative) and an anode(positive). There is a material between the two that has a higher resistance than the battery's voltage(basically the electrons are too weak to move through it). So the electrons can feel the force between the positive and negative terminals but they don't have the power to move. BUT when someone puts a wire between the two terminals(anode and cathode) the electrons can now move

  • @devigopalakrishnan2909
    @devigopalakrishnan2909 4 роки тому

    This video is great!!!

  • @TheSantanu99
    @TheSantanu99 11 років тому

    "if there is any such thing as reality" 0:46 - Classic Sal

  • @SaM0o0Na
    @SaM0o0Na 10 років тому

    will after the first tow videos I felt more comfortable because I could understand something now. I will contenw watching them and I hope that I will get A on my upcoming MT.

  • @knguyen542
    @knguyen542 7 років тому

    Would electrons not bunch up due to "like charges"? Thank you this video helped a lot.

  • @warrencurrymetal
    @warrencurrymetal 9 років тому +24

    18 people were amish

  • @htmlfreak
    @htmlfreak 15 років тому

    I believe total resistance in circuits are the following:
    In parallel circuits, the 1/R1 + 1/R2 = 1/RT (RT = Resistance Total)
    In series circuits, the total resistance is just the sum of all the individual resistors: thus R1 + R2 = RT
    Hope that helped.

  • @user-dv8we9kq5c
    @user-dv8we9kq5c 8 років тому +1

    i've learned that electron in a circuit cannot move at the rate of light. a lot of electrons in conductor just move at the same time when pushing the electric force. Im confused in that point.. i want to know the theory accurately

  • @dhurbarajpuree2992
    @dhurbarajpuree2992 2 роки тому

    This guy is so f*king genius. Love to learn from Khan academy. They are the gems.

  • @adsalazar12
    @adsalazar12 11 років тому

    When you say that the current is constant throughout the circuit, does that only apply for resistors in series or also in parallel? Is it constant always?

  • @abishekdahal403
    @abishekdahal403 12 років тому

    khan your voice is also a + point for your explanation

  • @jake_runs_the_world
    @jake_runs_the_world 10 років тому +4

    why dont the electrons just get to the +ve side through the battery , why all the way long and then ?

    • @kimballchoo
      @kimballchoo 9 років тому

      That's what you get for camping!!

  • @_underrated_dre_
    @_underrated_dre_ 2 роки тому

    So will the total resistance or actually the way of funding the total resistance be the same for a parallel circuit?

  • @vedatbajraktari5806
    @vedatbajraktari5806 8 років тому

    Nice job. Really im a university student but there in class is so boring and rabish lecture. Thank u, we looking forward to see more videos.

  • @kelvinmann7993
    @kelvinmann7993 3 роки тому +2

    I'm honestly just learning this so I can make circuit boards for music boxes. My brain is gonna hate me

  • @mitch3850
    @mitch3850 11 років тому

    Sal is the guy talking, Khan is the academy he represents.

  • @tadm123
    @tadm123 13 років тому

    I have a question is the Current always constant everywhere on the circuit? or just in the cable not going through resistors?

  • @poonamjoshi1101
    @poonamjoshi1101 4 роки тому +2

    I don't want to become an electrical engineer, I just want to give my best in NSO exam

  • @dulanherath5927
    @dulanherath5927 3 роки тому

    Best explanation👍

  • @narutosramenbuddy
    @narutosramenbuddy 13 років тому

    thank you for saving my soul AKA my GPA.

  • @takity
    @takity 16 років тому

    great videos!

  • @Harsh-iq1ph
    @Harsh-iq1ph 6 років тому

    How is the current constant thought-out the circuit I still don't understand plz help me

  • @EldonSchoop
    @EldonSchoop 13 років тому

    @xDivineForYou, Well you are correct that electrons flow faster than a few inches per hour (!), remember that electrons are pushing on other electrons in the cable, and the light would turn on almost instantly anyway. Think of it like a hose full of water that is just turned on. Of course the flow of the water isn't terribly fast, but the water that is currently in the hose is pushed out immediately, causing a seemingly instantaneous flow of water. Same deal with electrons. :)

  • @Thadnill
    @Thadnill 4 роки тому

    So does the voltage change in value after each resistor?
    If we for example have a circuit with a Voltage Input and voltage Output, with a single resistor in between, would the voltage input be the same as the voltage output? Or would the resistor change it's value?

  • @tonix1993
    @tonix1993 12 років тому

    Funny thing about the video is that in part 5:20 you say that electrons cant slow down just before the pass through the Ressistor.Thats not very right
    Well physics is so harmony that can allow that to happen xD
    think about it...if they slow down they compressed so they become a big minus charge in that area of the Circuit.
    Result? they slow down the upcoming electrons and in same time they push away on the other diraction the other electrons!!!
    Love physics ^^

  • @jaylonso6939
    @jaylonso6939 11 років тому

    You know a video is interesting when you dont look at the time once,thats what happens with all of khan's videos !

  • @nileshpatil8665
    @nileshpatil8665 4 роки тому +1

    I didn't understand why the current is the same and why the total voltage is the sum of all the voltage drops. I don't like expiremental proofs that is why I am so confused. Pls answer

  • @amirmolaei2056
    @amirmolaei2056 9 років тому

    tnx man ur the best

  • @Arthur85666
    @Arthur85666 10 років тому

    electrons actually travel very slowly, but since a lot of electrons are moving throughout the wire the effect is very fast.

  • @Pev0Gaming
    @Pev0Gaming 6 років тому +1

    10:44 How did he get that when he divided both sides by 10?

    • @Pev0Gaming
      @Pev0Gaming 6 років тому +2

      wait i remembered he got 2 for the Current (I) by using I = V/R
      Which is I = 20/10
      So THE CURRENT IS = 2
      I GET IT NOW YAYAYY

  • @ShivamSharma-me1sv
    @ShivamSharma-me1sv 9 років тому

    well u are saying that e- are less eager to go to + terminal after each resistance and after the last resistance there will no potential difference because of all resistance potential drop so why would e- go toward + terminal after the last resistance. i think i did not understand the actual mean of potential drop . please explain

  • @neurel111
    @neurel111 13 років тому

    Electrons don't move across the circuit anywhere close to the speed of light. Their motion propagates at the speed of light. So when the first electron moves it takes the last electron to move as much time as it would take light from the first electron to reach the last electron across the circuit.

  • @11031992em
    @11031992em 13 років тому

    sir, do you have "wye, delta" circuit analysis examples?,

  • @Physicsandmaths
    @Physicsandmaths 15 років тому

    Yes, if the material is above its critical temperature it's not a superconductor.

  • @viktorgoa
    @viktorgoa 14 років тому

    yes, they travel slowly. The reason why its fast, that its going in waves

  • @kittyanddogy
    @kittyanddogy 6 років тому

    How does current I doesn't decreass as i = v/r

  • @alissajeanfreau7741
    @alissajeanfreau7741 6 років тому +1

    I'm confused on how in the beginning, he said that the voltage is the same no matter where you measure, from at the end there being a difference in voltage from the beginning of the resistor to the end

    • @atombarn223
      @atombarn223 2 роки тому

      So your voltage will be the same when you put your meter from the positive and negative of your power supply OR the start R1 to the end of R3. Not in between each resistor. The Current (I) will be the same in between each resistor. To get your voltage in between each resistor you'll just take the current total and multiply it by the value of the resistor. Hope I was clear enough and this helps.

  • @Becca11Dance
    @Becca11Dance 12 років тому

    Is there any such thing as reality? That, my friend is a very good question.

  • @cursedswordsman
    @cursedswordsman 10 років тому

    So the voltage is different after every resister? There is no one voltage for the whole thing since it's different everywhere?

    • @JarsOfRedClay
      @JarsOfRedClay 10 років тому

      Well yes more or less, it is different after every resistor since there's always a drop(difference) .Voltmeters can be positioned a number of ways.Normally there would be just one connected to the power supply and as the current flows it calculates the potential drop/difference so it does all the work. However, I think he only placed various voltmeters to better explain the concept.

  • @mini-337
    @mini-337 Рік тому

    Thank you sir

  • @nana_smallmango
    @nana_smallmango 3 роки тому

    I love Khan Academy

  • @kamikrazi123
    @kamikrazi123 13 років тому

    How is this guy so damn smart??

  • @bladervinay
    @bladervinay 12 років тому +1

    Ha ha 'Oh oh its my wife she will mind if i dont answer but anyway' Ohhhh you are brilliant Sal!!!
    Funny and brilliant

  • @raghulsankar1153
    @raghulsankar1153 4 роки тому

    why is the current same throughout the circuit . if the resistors impede the flow of charges then the rate of flow of charges must be different right

  • @Anintora
    @Anintora 3 роки тому

    im convinced sal thinks we all live in a simulation

  • @sharkbaitoohhaha2341
    @sharkbaitoohhaha2341 12 років тому

    If Sal ever has kids, they will be all-knowing!!