Lec 11: Magnetic field and Lorentz Force | 8.02 Electricity and Magnetism (Walter Lewin)

Magnetic field
Lorentz Force - Torques - Electric Motors (DC) - Oscilloscope
This lecture is part of 8.02 Physics II: Electricity and Magnetism, as taught in Spring 2002 by Dr. Walter Lewin at MIT.
This video was formerly hosted on the KZbin channel MIT OpenCourseWare.
This version was downloaded from the Internet Archive, at archive.org/details/MIT8.02S02/.
Attribution: MIT OpenCourseWare
License: Creative Commons BY-NC-SA 3.0 US
To view a copy of this license, visit creativecommons.org/licenses/b....
More information at ocw.mit.edu/terms/.
This KZbin channel is independently operated. It is neither affiliated with nor endorsed by MIT, MIT OpenCourseWare, the Internet Archive, or Dr. Lewin.

[@kumaraakarsh7232]

I was feeling sleepy,and so decided to watch Prof.Lewin,and now it's all good.

[@rafikamin6617]

I am in fever 😷 and watching this

[@Sznajderification]

Truly scientific attachment to details. Profound understanding of physics. Passion. Sir Walter Lewin, you are a living example of how we should explore the world.

[@ArtyBoney]

This man is a legend. Lucky students who had the chance to experience Walter Lewin's lectures. So sad that in my country we don't have such opportunities to have such inspiring professors and live experiments to show us how things work.. For example we are learning about capacitors, and sure students can solve different problems with them and know some stuff, but the fundamentals for their practical usage and how they EVEN look, not even a bit, because apparently it's too "hard" to put a real picture of them. Our universities still have if I may say 'communism', nothing is fun anymore, but for me I can say that god bless these guys who put such amazing explanations and animations for free on KZbin!

[@alokverma3311]

please go to the hcverma.in .......and also enjoy physics

[@ankangayen6670]

Dear Walter sir, The person inspired me to explore physics is you. So 1st I thank you with all of my heart. I have a very silly question but I cannot stop asking as I am not at all getting satisfied with the available answers in books. We know that the Magnetic force on an electric charge is perpendicular to the magnetic field direction. But why should it be ? If the charged particle had kept on moving in straight line perpendicular to the direction of magnetic field, is it going from lower to higher potential of any field ? I think no. Then why would the magnetic field oppose the electric charge's straight linear movement ? I cannot mentally accept the answer as "Lorentz force", as it doesn't depict what's physically happening in there ! Also, it gets more absurd when the moving charge starts moving circularly due to the magnetic field (like Charges inside a Cyclotron). I cannot visualize this ghostly situation where the charge is revolving due to a centripetal force, which is exerted by none at the centre !

[@leftenanalim]

23:49 "I don't think" Walter Lewin: Neither do I

[@RalphdaCuban]

Brilliant! I love these lectures!

[@adarshapriyadarshansejpada7681]

Love you Lewin sir.....I am a big fan of yours as well as of physics ❤️❤️❤️

[@user-cx5ni7me6l]

Thank you for uploading this ✌🏻♥️

[@234vmv8]

his lectures are really helping me through exam 😊👍👌

[@mustafaragab6531]

Thank you very much Professor You made physics really easy, all the love

[@JonathanHilierChannel]

I am a fan!!!! Stumbled across this on my research project and I can say that almost every line of info I used!(well, paraphrased)

[@nikolozgilles]

LORENTZ FORCE GO!!!

[@MsVicki1997]

Don't we all wish we could be stellar students at MIT?

[@rafikamin6617]

Ue

[@justalazyguy.0_0]

I imagine that

[@sujithraman1]

Great lectures..

[@YommiOfficial]

Whoa. Very good.

[@espendahlandersen8109]

Go to Walter Lewin's own channel "Lectures by Walter Lewin" to watch this in good quality. This sucks.

[@darshanmali7889]

thanks

[@himanshusingh0]

Thanks

[@grubybueno]

gracias, una pena que recién me enteré este es el link kzbin.info/www/bejne/rmKQhJyYrK6Dg5Y

[@user-cx5ni7me6l]

Thank you! Good to know

[@diptanshude2525]

the sound quality is poor.........the lecture however was one of the best i have ever listened to

[@JoseOlin]

No subtitles on this one? Any way to contribute with the subs? Thanks for the upload. Keep the good work!

[@justalazyguy.0_0]

Watch in on the main channel

[@earlpierce7173]

There are magnetic monopols now. Companies like Correlated Magnets can now print magnetic poles in 'North' or 'South' polarity with any desired strength via pixels from a 3D Magnetic printer.

[@MuhammedhilmigulluBlogspot]

nice hand print and legend teacher

[@claricea5353]

I will pass my physics exam thanks to these lectures!

[@yxor]

did you pass ?

[@harshsinha8406]

Friedrich Nietzsche no he didn't 😂😂😂😂

[@LuckyKumar-uf6xs]

Nice sir

[@jakesky100]

I have a couple of questions. First, why is the magnetic force perpendicular to velocity? You say it is an experimental fact, but is there any deeper reason to make this more intuitive? Something having to do with special relativity maybe? Also, when you run a current through a magnetic field, doesn't the current's magnetic field superimpose itself over the external magnetic field? I am referring to around 33:00 when you are calculating the magnetic force on the wire. Thank you for taking time to answer, I really appreciate it!

[@Qladstone]

There is no deeper reason to physics. Physics is a creation of humankind to find regular and coherent patterns to describe the physical world. All theories are expressed using mathematics and validated with empirical study.

[@S3jr4]

Science, bitch. Thank u Walter Lewin and Walter White.

[@sciencemathtutorial]

Bookmark: 24:50

[@manshichahal1123]

Sir, how current can produce produce magnetic field

[@tomerfeinaru9726]

Dear Mr. lewin, What is the force that makes compass to show the north ? And the force that makes 2 magnet to attract ? This is not the magnetic force, because it is vertical... Am i right ?

[@RCrosbyLyles]

Magnetism has to do with the relativistic transformation of electric force between reference frames, so it is mathematically impossible for there to be a magnetic mono-pole.

[@UditDey]

the idea of magnetic fields itself is made redundant by relativity

[@jacobdavis6230]

I'm glad I finally found someone else who was thinking the same thing.

[@JensenPlaysMC]

It is an experimental fact the only reason relativity says there aren't magnetic monopoles is that we transform the field equations using the lorentz transfotmations. this only shows that we cannot transforms away an electric field in favour of a magnetic. if we allow magnetic monopoles into Gauss law for magnetism, we would draw the same conclusion about electric fields generated by transforming the magnetic monopole equation

[@dr.ashrafabdelkaderelboss9055]

I think he applied Fleming right-hand rule in case of the generator in a wrong way b

[@shobhitkumar98]

If a charged object is sent into a uniform magnetic field it undergoes uniform circular motionIn circular motion the object is acceleratedSo according to Maxwell it should emit energy in the form of EM waves and spiral and collapseAs was the initial problem with Rutherford's model of atomWhy doesn't it happen?

[@jamshedsaeed9445]

why we wrote V cross B instead for B cross V

[@fwritter346]

It's must know why magnetic field create when current passing through a wire???

[@unpopularopinion9976]

The kinetic energy is emitted resulting in magentic field, when the electrons are under motion

[@LorenzoC36]

youtube should never lower the quality of these videos over time

[@jimmydwallace]

Address Moore's Law?

[@robertbach9376]

haha, he said "all vier."

[@muratcan4624]

Magnesia city still exists under the name "Manisa" in Turkey.

[@lucatancredi]

class 5B should watch it tll 25 min for the moment

[@adiletbeishenov5731]

I build simple dc motor series connection. It turned more then 500 rev/permin and then breaked. 😂😂😂😂

[@user-xl8uo9gp9p]

He Treated current as vector!!! 11 minutes 5 secs-11 mins 15 secs.

[@themax1234521]

अंशुमान अवस्थी In cases like this, the net current can be treated as a vector. Nevertheless, in current addition (as in circuits) it isn't.

[@suryadeeptonag9284]

No the I here is the product of current and the length of the conductor and the latter is a vector so it's a vector

[@alokverma3311]

current has a fixed direction higher to lower potential ok......In many cases the direction of the charge flow changes from one point to another, but the amount of charge passing a given point in a wire is the same at all points...........this is true for some particular cases

[@hellboy1438]

why the video quality is poor?

[@j.d.b.pennamesonofharraant3367]

T⚡B 2nd law of Thermodynamics Unipolar Sun and Moon Above Earth

[@prathamvasa916]

once I found these videos I trashed my physics textbooks because they were nothing in comparison to this. thnx a lot :)

[@BuzziMuzzi]

Is he dutch?

[@BuzziMuzzi]

JanWey91 I know

[@ch1ck3n65]

+Nihar Baijal So much anger

[@ch1ck3n65]

+Nihar Baijal you do realize that you started the name calling on a comment that was made one year ago?

[@JanWey91]

***** his lack of courtesy does not equal rudeness, your reaction however was rude.

[@ch1ck3n65]

+Nihar Baijal I dont think you understand how trolling works

[@qualquan]

I believe Faraday gave the physical basis of the Lorentz force direction which does NOT require the cookbook like right hand rule. Please post if u know it. These hand rules work but are very unsatisfying intellectually in 3 dimensional situations.

[@vibodhj349]

+qualquan they just give a quick way of doing things!

[@qualquan]

+Vibodh Jadhav I know its a quick cook book method. But the intellectual under pinnings are better. They EXPLAIN why the cook book works and are more satisfying intellectually. I believe Faraday provided it but sadly nowadays even the teachers practice "cook-bookery".

[@AdiCherryson]

Many understatements and axioms. Actually not explaining a lot more than a textbook. Just it is fun to watch the experiments. I really regret that so many of you describe him as a tutor role model. Only few have mentioned quantum mechanics and relativity as those fields that actually try to explain those phenomenons. The Lorentz force is not explained at all. He just states that it is experimental fact. Well it is really helpful. Say aloud that physicists have no idea why this is so and no field lines make any help here. Another example. I saw only one person in the comments asking what is it with that metal plate and how is it affecting electric fields. But you say well this is obvious. It's the Faraday cage. Well I don't know if it obvious at the beginning(?) of the "electricity and magnetism" course but it is for sure yet another example of learning by heart. I bet no one of you can derive why the Faraday cage does work. No, you just think that it is simple but really didn't give a thought to this. It's not. You can try wikipedia if you don't believe me. Next thing is the definitions of the electric and the magnetic field. Have you really understood what is the definition of the later? And did you notice that it is all about measuring the force and deriving the rest from it (since we know how to measure force). If so then how to derive the magnetic field vector knowing the velocity of the charge vector, magnitude of the charge and the force acting on it? You can't right? Or haven't you really thought about it. And did he pointed it out? I know this is all basics but isn't this lecture all about basics?

[@maltejohnsson8578]

Can you point me to better or more thorough tutors which are better than this man?