Lec 5 | MIT 8.02 Electricity and Magnetism, Spring 2002

[sprattysy]

some really good stuff here

[ienjoyapples]

haha the end..aw i love him like a crazy granduncle

[stavrospod]

he really is the best teacher I have ever seen..he loves what he does+he loves physics=success in teaching and we learn..great lectules..all of them..

[distractionxx]

some sweet info here

[dailypinoyshowbiz]

Your video is a favorite on San Marino

[EclecticSceptic]

At 30:20, why does he keep touching the metal plate? What does that do?

[SZDarkhack]

@EclecticSceptic Here's how this process works. When you rub the glass with the fur, the glass gets positively charged. Then, you place the conducting plate on top. Since the plate is insulated from everywhere (glass is an insulator, and so is air), it stays uncharged. When you touch it, however, it finds a path to draw electrons from the earth (through your conducting body) until it negates the charge of the glass. That's the simplified explanation, of course, but it should do.

[stino22]

At around 17:00, should the equation be E = -5x^4? I might be confused, but it's the derivative with respect to x, correct ?

[stino22]

@stino22 scratch that. Stupid me, I didn't see that it was 10^5, not 10x^5

[mark942]

Could someone perhaps explain the electrophorus procedure? Cheers

[mdgreg]

"...Nature can Do this Effortlessly", it doesn't Help When he Implies Nature has a Consciousness.

[PreseidentRaghav]

why he is touching the eletrophorus each time with the finger?

[GKrizzel]

@PreseidentRaghav to neutralize any charges before he puts on the wanted/desired charges

[meliatthedisco]

The Faraday Cage demonstration was amazing, I need a teacher like him and a university like MIT.

[aavindraa]

22:34 radiohead fan

hi reddit :-)

[silverag477]

...this guy should seriously have his own tv show

[OKMUNWURX]

@silverag477 He does. You are watching it. Internet 'TV' is what we have now. Beats antenna TV and cable TV; no commercials!

[silverag477]

@OKMUNWURX sweet :) you think other universities would have something going on like this? like Stanford or Yale. That would be sick. learning easy without paying 40 grand :b

[andywalkerplumber]

It is amazing how much of physics is "non-intuitive". I agree, this sure beats watching Seinfeld re-runs over and over again. The human brain (most) has the need for stimulation of some sort, and its wonderful that certain brains are gravitated to this type of thing. Walter Lewin's animated character is what makes this fun, and all teachers should endeavor to bring this magnitude of EXCITEMENT to the subject they are teaching, whatever it may be.

[Toshon1990]

thanks from bangl.adesh

[mess1ahh]

a Big Thanks from Brussels!

[otinanai19920z]

many thanks from greece!

[blueishdude123]

he has beautiful handwriting



[BrezHurley]

I <3 Walter Lewin

[stranger1206]

perfect circles 38:00

[rinwhr]

Lol that smiling planet on his shirt looks like he is high on voltage or something

[digicho]

So... can doc tell us if there is any scientific explanation why E is defined on partial derivatives? Except that ones that come from need for compatibility with simplified Maxwell's equations? Math and healthy reason suggest total derivatives.

[HINIELD]

does anyone know why derivative of potential is negative electric field?

[uberfishy1pker]

@HINIELD remember to calculate potential he integrated the force with respect to the distance involved in bringing a charge from infinite to a radius R? and force*change in distance = energy. and electric field is the opposite of an applied force so thats why its negative.

[hirte3]

@HINIELD look at 4:45.

the derivative of Q/4(pi)(epsilon zero) r is like 1/r or r^-1, so you multiply it by -1 and raise r to the -2nd power, or 1/r^2, which gives - Q/4(pi)(epsilon zero)r^2.

[jjfisico]

Great.

No se ustedes pero a mi solo me llega hasta el minuto 30. Me pregunto si el video esta colgado bajo otro nombre también....

[theonekh]

Amazing!

[MrScienceGuy94]

I hope i get to go there I would major in Math and minor in History

[Arycke]

Wonderful series of lectures. I'm a physics minor (surprisingly, though, I'm up to par with the physics majors just from my own readings and videos), and these videos are wonderful supplements as my lectures are uninspiring and not very informative. Thanks :-)

[xartvinx]

thank you sir..

[AzteKpr1de]

i don't get it XD

[esquadmiller]

What text does he use? Does anyone know?

[giovanni9107]

"Physics for engineers and scientists" by Hans C. Ohanian

[MastahShake666]

We use a book by a guy named Purcell. Berkley Physics Vol II: Electricity and Magnetism. My girlfriend goes to MIT but she never tells me anything like that. But if you want a really good book on E&M, get the Purcell book. It's all in plain english and math language.

[starringhobo89]

I like this professor. Great. Expressive. I definitely don't fall asleep. Props to him :)

[salahaddin2009]

These videos are valuable.

[Blueroom57]

Currently taking PH213 (equiv. of this class) at a community college. Have a good teacher, but these videos are a GREAT supplement!

End of this lecture, they stop the video as he open the door of the cage but before he steps out. I don't think the cage or vandergraph was discharged before he opened the door. Would he have received a nasty shock if his foot touches the ground while still holding the cage door if they failed to discharge it before he got out?

[PreseidentRaghav]

@Blueroom57 yeah same doubt here

[mamdk]

Electrophorus is a cool way to transferring charge

[calvinnme2]

I'm someone whose professors acted like teaching E&M was a prison sentence. As a result, I could work the problems and got an A but had no insight into the subject matter. Now I have a job that requires that I know this. Prof. Lewin's lectures are making these concepts clear for the first time. MIT is truly doing a great public service by making this stuff available for free.

[wilzy123]

Walter Lewin makes these lectures so great!!!

[Axmedkoole]

This is what could cost you $ 20-100 a unit class. Thanks for posting. The only bad thing about this is no credit for your physical academic.

[thaiden03]

GOD bless MIT for such a huge social contribution!!!

All this knowlege for free. AMAZING!

[stewitr]

@thaiden03

I don't think 'GOD' has much to do with this or anything.

[JiHsianLee]

great!

[hotdave86000]

I'm just an average youtube viewer watching MIT stuff for entertainment. lol

[ratatabatata]

@hotdave86000 go roll a j

[hotdave86000]

the tysonstyne monster just joking seriously

[nfskrumps]

I'm just an average youtube viewer watching MIT stuff for entertainment. lol

[yetidh]

i think this prof will save my grades...why the hell does everyone else has to explain physics so complicated?

[chuyqa]

these lectures make me feel warm and fuzzy

[tomk189]

for some reason....i like this teacher than my teacher....i should of gone to MIT...man....

[Shawn3340]

this helps anyone? my physics is autotutorial , no lectures! i'm using College Physics by Giambattista Richardson Richardson. I'm behind and not much ta or professor help, is it possible to learn an entire Semester of this EM physics in 4 and 1/2 weeks? I can learn most subjects at the pace of about 1 credit hour per week pace, so i can do it with EM. Should i be watching it or is it wasting time? I'm doing problems while listening to this course, should go to my own ta's more?

[thefullmonte03]

I learn a lot and get a lot from my book, but you can't ask a book questions. Go to lecture....

[hunterneng]

struggling with my physics, and with less than a 2 weeks to exams..should i be watching this??

[psychobollox]

i hope you were!!!

[aaronaarestad]

He saved my grade.

[guyov]

Great lecturer