Circuits (part 4)

[hockeymo]

QUESTION:

In one of his earlier vids he said that the current throughout the circuit is constant but in this video he said that the current are different at diferent places? wouldn't there be a "build-up" of electrons if there different currents????

[cowzrule101]

0:38 - Sal: "4Ω, 8Ω, 16Ω..." - Me: "Powers of 2, next should be 32Ω" - Sal: "I am actually making numbers up on the fly: 16Ω (again)" - Me: "FFFFFUUUUUUUUUUUU..."

[shenoycdx]

what do u look like?

[chillerized]

@shenoycdx Theres a video of him at a conference or something with Bill Gates on his channel

[pseudorealista]

You should do one circuit w/ 3 identical resistors in parallel and then tell us what happens to the voltage, the current, and the brightness of the two lightbulbs left when you take one of them off the circuit.

[yamenhawit]

@khanacademy You're videos are great! However, I would like to request that you do more videos for electrical engineering, covering further topics such as inductors, capacitors, RLC circuits, etc... That would be great if possible. Thanks again.

[ChrisTheDIYguy]

Is there anything you DON'T know? haha thanks though.

[slyfox551]

can someone please tell me if theres a potential dividers video?

[WVENGINEERING]

Thank you for these videos... Your videos are the most helpful I've seen online.

[benja303]

question

could we have simplified all the resistors at once

[sh3rl0ck999]

OK GUYS JUST CALM DOWN, the 1/16 he wrote looks like 1/4...just don't get confused...in the diagram he drew there was two 16 ohm resistors so Rt does equal 2 ohms.

[bentodd1]

1/4 = 4/16 you messed up a little on the second 1/4

[TheMichaeljohnny]

Thnks u r gr8



[fighter91]

Wait I'm pretty sure he made an error when adding up the top resistances. I think his fractions are incorrect because isn't supposed to be (4+2+1+4)/16? The last number is supposed to be 4 not 1.

[kokaiini]

thank you!!

[hazara67]

I love u SIR..... for all of these great vedios......!!!! thanxxxxxxxxx alot

[609197]

thanks man. i have a test on this really soon

[DaniellaRox123]

@609197 hey i've got a test on it too! lolz...to be specific..on wednesday =P

[DMerk2012]

I <3 you

[griftorifto2]

Mmm loved me a bitta hairy circuit problems.

[FLAMERNECRO]

THANK YOU !

[ishan0833]

great tutorial..

[IPMountainDew]

Ok sweet vid but what if we try to find the voltage, or each value of the resistance (not given)

[griftorifto2]

@IPMountainDew  I don't think finding each value of the resistance is possible only possible values for each that would make the equation true. Since there would be a huge amount of possible values It would qualify for as a problem of "Great hair density and length" ;)

Finding voltage given all resistance values and current is very possible(simple) however.

[metalmaniac767]

At the start I actually said, "This guy is a lunatic!" Great video :D

[NinjaMotion]

good job resolving it, i dont realy like hairy stuff

[animefreak619240]

You shaved that problem.

[gbmack2000]

at 5:55 don't you mean there are two resistors left in series, not parallel?

[TheBrigadeCheif]

@gbmack2000 He corrects himself shortly afterward.

[alifawad1994]

Sal could you please make lessons about Wheatstone bridges, potientiometry and kirchhoffs Law. Thankyou 

[richimf]

this also help me itunes.apple.com/us/app/star2d­elta/id417605678?mt=8

[jessiemsy]

Why can't you teach my physics class!? Thank you so much!

[MsRoseapple]

Reli helpful on my study !thank you very much!

[spysr]

Hairy?

[ag1293]

These videos are spectacular! I would love to hear you explain the Wheatstone Bridge if you have the time!

[TheUnchainedBeast]

good work (Y)

[Mcplumpyboy]

I watched this after my circuits test... I would totally ace any question now = ) thanks!

[comecra85]

Do students in US schools actually understands all these concepts? That is can they construct a circuit themselves? I thought US physics education is not strong.

[jffersontube]

@comecra85 These are very basic concepts with very, VERY basic math. Don't believe everything you see on the internet and TV about people in the US. There is nothing remotely difficult about this.

[nickrohn93]

@comecra85 Have you ever heard of Nasa?

[nickrohn93]

@comecra85 Or MIT, Harvard, Princeton, Standford, Yale...

[eefritz]

check out Dunwoody College of Technology's on series/parallel combination circuits (by Eeris Fritz) for extra help which offers a two step method that is easy to follow.

[DRAN4612]

MATHEMATICS

[poshablyposh]

haha thanks fo all the videos! you teach better than my teacher. really;))

[boeing747200lr]

What is the meaning of a hairy problem? Btw, very good explanation.

[robo2000nitro]

"alot less hairy" lol cos you gave it a good shave :)

[SecretAsianMan7]

Also I think it'd be nice if you did some optics videos, wave phenomena, diffraction gratings, double/single slit interference, thin films, resolution!

[SecretAsianMan7]

Yes RL, RC, and LC circuit videos would be helpful! Also Maxwells laws, Biot-Savart law, induced emf would be awesome!

[WTFnigga001]

Love these circuit problems!

[nutnub1]

In what way is this hairy? It's all linear, in that you can simply solve for one thing at a time.

[max1916251080]

I don't get this, you say that the voltage is the same at any point in the circuit, but in this problem i have the V is 100v, and she says that V3 is 6v. I thought it was the same no matter where you are on the circuit

[jakeo3553]

@max1916251080 In the parallel portion of the circuit the voltage is constant across each "branch". But if there are portions in series then there are voltage drops across these series-resistors sections. So there are voltage drops across these collection of "branches"

[franknostradamus]

Thanks for all the video's so far, they have helped me a lot with my studies!

But im still left with some questions about circuits; what will happen if you add mutiple U's (dunno the word :-) ) intro the circuit? What will happen with the flow of electrons? And what will happen if you put them in parallel?

Thanks for your clear video's! Looking forward to the new video's!

[lightningblade79]

WOW this video explained it so well, haha the other day i was struggling with the text book to understand this =D your greatt thankss :)

[KKinsane2009]

my god, this is more confusing that getting into orbit in orbiter O_o still, I get it, thank you for your time and effort khanacademy :)

[itsnamed]

excellent .the way of explanation s awesome.thank you very much.expecting more

[hugtheoboe]

YES! I got the right answer before you even finished explaining! Thank you!!!!

[xxfuturerevealedxx]

GJ GJ MAN GJ hahah great tutorial buddy

[Ritzoid]

How can the amperage be 8 amps if every branch of the parallel circuit is different?

[Nervasin]

kirchhoff's current law

[ajskilton]

it's 8A in total but this is shared amongst the parallel resistors(pathways), that's the whole point of the video!

[bellatesla]

Watch it again and again until you get it or go back one video you'll then know it forever.

[VWinUgo]

I need a RC circuit video... lol Thank you for the videos on circuits in series and parallel!

[jbohbot1]

lo RC is really more complicated...

[woodenjaw]

i got 2.5!!!!!!

[jbohbot1]

lol i got like, way off!

[youriemhei]

thanks for your kindness and generosity to put up this vid for those physics learners/. :)

[zackalphaomega]

thanks for the vid bud

[jmnc05]

I disagree with the comment below to some extent, only because some stuff you draw I can't read but you say what it is out loud as you are drawing it so I know what it is.

These videos by the way are awesome, thanks for putting them up!

[hacksign000]

how do you calculate current through each ones and the voltage through each one

[Nervasin]

the voltage at each resistor is just the voltage drop. to find this you first have to know the current going through all the resistors in the series configuration shown at the end, this is 8 amps, then you multiply the total current by each resistance. The current through each resistor in series is the same for the equivalent circuit, and in parallel resistors the voltage across each resistor is the same so you can use ohm's law to find current.

[polos505]

totally understood. thank you .

[fussners]

There isn't a math error. (1/Rt)=(1/4)+(1/8)+(1/16)+(1/1­6). The way its written the last (1/16) looks like (1/4) but its really (1/ the resister on the bottom of the group hes evaluating.

[magicwisard10]

2:51

[bboy1600]

Thanks man, You're Awesome :)

[L1nnaea]

Pretty sure there is a math error at 2:45. It should be (4+2+1+4)/16.

You get the point across anyway.

[plo1T]

Look at fussners comment up there.

[gerardosilva1980]

Great video!

[anava84]

I wish the lectures on magnetism weren't under construction :(

If light and optics are added, attending physics class will not be necessary!

Thank you very much for everything you've done Sal! Your much appreciated.

-PsubD

[idricool]

Thank you !

[tiptopmini]

Thanks for saving my grade again!! Great videos, I'm loving them :)

[Nandine2]

actually I don't get voltage dividers and EMf......(sneakily asking you to do a video on it!!)

[Nandine2]

wow great video, although I don't really have problems understanding electronics in my physics class but this video really does give an intuitive feel. and I am not just saying that!