The Wonders of Electricity & Magnetism - Sept 2005

Family Adventures in Science & Technology
Sponsored by the MIT museum.
Talk given for kids (and their parents). Prof. Lewin covered quite thoroughly the basic concepts between Electricity and Magnetism with many demonstrations. He demonstrated a device (the Kelvin Water Dropper) that can create some 20,000 Volt using only running water. He charged a girl up to 100,000 Volt using a Van de Graaff generator. Her hair would spread and stand up - very funny. He beat a boy with fur to charge him up to some 20,000 Volt and he discharged him through a neon flash tube which lit up briefly.

[@SaschaVIE]

These recordings are the best cures for any kind of depression. Interesting, entertaining and heartwarming. Thank you!

[@lecturesbywalterlewin.they9259]

:)

[@EternalDucks]

Science needs more Walter Lewins. I couldn't stand my high school science teacher much to my regret.

[@lecturesbywalterlewin.they9259]

+Tom Clancy Dear Tom, not all high school science teachers are great, but some are.

[@Vonuho]

My physics teacher has the knowledge. But still he do not have such ability to implement his knowledge to his students. But you are my motivation for physics.

[@thescientificworld6032]

I am NEET (India-PMT ) Aspirants.

[@prudhvirockz3290]

@@thescientificworld6032 mee 2 bro all the best

[@spiderpooldevi243]

All teachers are not genius and all genius are not (good)teachers It is very hard to find one who is both genius and a teacher Probably one in a million

[@EmanuelPontes1983]

Dear Dr. Lewin, your videos are truly inspiring. The energy you put up, and the love you have for physics is contagious. I don't have the need for physics knowledge on my day-to-day life nor to get my job done, yet I find myself watching your lectures just for my own personal enrichment. As you stated in one of the videos, having the knowledge of physics will allow me to see more of the beauty in the world and properly appreciate it. My son is currently 4 months old, and I truly expect that one day I am able to show him your videos. They are timeless. Thank you!

[@lecturesbywalterlewin.they9259]

Thank you for your kind words.

[@francescocuccu4218]

I wish I could attend even just one of your lecture. Thank you for your fantastic teaching. Greetings from Rome, Italy

[@lecturesbywalterlewin.they9259]

You are very welcome

[@estoy1001]

Obviously, when a strange old guy asks if he can beat you with cat fur, you must oblige because science!

[@TheMinhdynasty]

The conventional symbol for current is I, which originates from the French phrase intensité de courant, meaning current intensity. ... The I symbol was used by André-Marie Ampère, after whom the unit of electric current is named, in formulating the eponymous Ampère's force law, which he discovered in 1820. From Wikipedia.

[@shadow247]

If i Had physics professor like you in college I probably would of been more interested in majoring in science. Nonetheless, It's always nice to learn something new and these videos are fun to watch

[@maxwellsequation4887]

Best Physics teacher in the world currently. I might have said of all time, but Richard Feynman rightfully owns that title

[@shivambhatti5496]

Hello sir, I would like to you in person and share the joy of learning from You. hope to meet you once in a life sir. Thank you sir.

[@lecturesbywalterlewin.they9259]

Thanks for your kind words

[@michellewest6929]

Thank you so much for putting up this lovely lecture exclusively for students. It’s sad to see that there’s very few people who actually curate proper lectures to a student’s taste. There’s a lot of students out there who genuinely appreciate Physics and want to learnt it not because it is what comes on their exams but purely because they gravitate towards it. Engaging talks exclusively for students really scream true inclusion in democracies where equal opportunity is meant only for those above eighteen. This was a fantastic lecture; it zoned me in for 2 hours straight. Thank you:))

[@Dakkyun]

Legend has it, every professor have this hairstyle when they age.

[@NegruVodka]

sir, you rubbed the glass rod with silk fabric; therefore you made the fabric negatively charged and the glass rod positively charged. but if you wait too much, then they will go back to their original electrical state. This is because naturally they have that kind of properties whether negative/positive. Or they are with no electrical presence and the action, rubbing (friction) made them produce some electricity and just because of the characteristics of two different material, produced-load distributed according to it? my second question is that what would happen if you would use another material which can attract positive charge faster(or maybe easier) than glass rod, then would it be possible to negatively charge the rod as the positive property would be taken by the other material?

[@lecturesbywalterlewin.they9259]

charge does not leak off easily as both are insulators. question 2. consult TriboElectric table.

[@cpgamespainting4084]

Symbol " i " was for intensity. Originates with Ampere. Using V = IR for electricity flowing in a closed circuit: V = Potential. I = Intensity. P in watts = Product of Intensity and Potential. Observed with traditional heating elements and some lights using substantial energy and giving off more heat. Your power (kilowatt hours) consumption is higher for a toaster than a television. The potential is the same from the outlet, but different appliances draw more.

[@lancequek5203]

One of the best lecturers since Richard Feymann

[@shashankn7785]

Mr. Walter Lewin, I cannot express my greatfulness to your fantastic lectures. I have been viewing your lectures for 3 years now and I have learnt so much without even conversing with you! Wish I could contact you in some way.Thanks a lot once again. Hope it will cherish my dream of going to MIT:)

[@lecturesbywalterlewin.they9259]

:)

[@realcygnus]

Priceless Content.......thE BEST Science Teacher/Lecturer Ever........an actual Living Legend !

[@lecturesbywalterlewin.they9259]

😊

[@diegoarana5862]

Mr.lewin you are the best physics teacher I've ever seen.

[@lecturesbywalterlewin.they9259]

thank you

[@diegoarana5862]

@@lecturesbywalterlewin.they9259 I almost contemplate skipping my E&M classes so I can just watch your lectures instead but my incompetent teacher gives complex problems that take 20 minutes to solve in the middle of learning something new and takes it as participation grade so sadly that isn't an option but if she did not do that I would definitely just skip and watch your videos.

[@DrR1pper]

Anyone know the answer to the question at 27:00 for why some confetti permanently stay on the comb for a long time? Edit: I think i may have figured the answer. When the confetti made contact with the comb, transferring some of it's negative charge to the confetti, the difference in charge between the confetti making contact and the comb became less than that between the confetti on the comb and the confetti on the table now. Therefore a force of attraction exists between the confetti on the comb and table, hence the rebound by a lot of the confetti initially. Then once the overall negative charge of the comb was reduced by this action of fleeing confetti taking some negative charge with it each time, there was not enough negative charge left in the comb for there to be sufficient force of attraction between the confetti on the comb and table to overcome the attraction force between confetti on the comb and comb and therefore unable to pull further confetti off of the comb. Also after all the rebounding had finished, had the professor brought the comb a little closer to the confetti on the table, perhaps a few more confetti's would have rebounded/fallen off the comb to the table because bringing the confetti on the comb closer to the confetti on the table will produce a greater force of attraction between them with whatever remaining difference in charge exists between them. Anyway, just my theory. :P

[@lecturesbywalterlewin.they9259]

+DrR1pper I know the answer.

[@lecturesbywalterlewin.they9259]

+Lectures by Walter Lewin. They will make you ♥ Physics. I cannot follow your reasoning. Why is the confetti attacked to my comb in the first place - the confetti is not charged? What would be the necessary condition for the confetti to be repelled after it touches my comb? If you can answer both questions you are well on your way to explain why some confetti sticks to my comb and is not repelled by the comb.

[@DrR1pper]

Lectures by Walter Lewin. They will make you ♥ Physics. Sweet! Fyi, i just wrote down what i think is the answer.

[@DrR1pper]

Lectures by Walter Lewin. They will make you ♥ Physics. I just re-wrote most of it to better explain my theory better. Please let me know what you think. Thanks. :)

[@lecturesbywalterlewin.they9259]

+Lectures by Walter Lewin. They will make you ♥ Physics. I cannot follow your reasoning. Why is the confetti attacked to my comb in the first place - the confetti is not charged? What would be the necessary condition for the confetti to be repelled after it touches my comb? If you can answer both questions you are well on your way to explain why some confetti sticks to my comb and is not repelled by the comb.

[@This_comeback_is_personal]

I admire you the most you changed my life in 3 days

[@syedhaideralizaidi1828]

Sir, I Am A Student And As You Said That Teachers Who Make Physics Boring Are Criminals, I Have Been Through This But In This Modern Time It Is No Less Than A Blessing That I Can Have Your Lectures On Physicss And They Are Growing My Love For Physics More Day By Day! Sir You Are An Inspiration❤Love From Pakistan ❤

[@lecturesbywalterlewin.they9259]

:)

[@PedroLima-fm2fr]

Hi, Professor, thanks and congratulations by your wonderful lectures! (Being from Portugal, and in our use of latin origin language I suppose I can say "I" for current stands after "Intensity" as we call it "Intensity of the current" but I have not research real historical evidence to support this believe)

[@sreejithmlsree8187]

outstanding ...... great sir

[@lecturesbywalterlewin.they9259]

+Sreejith M L Sree Thank you Sreejith

[@prakashsharad]

Sir u are simply great...... Great.... thanks for ur efforts to enlighten us

[@lecturesbywalterlewin.they9259]

thank you

[@anubhav_jha_a.j]

Ur teaching showed me the beauty of physics so, Thank you very much for there lecture...and am from India i love you 😊

[@chaobao8198]

what an amazing teacher! bravo!

[@lecturesbywalterlewin.they9259]

Thank you Chao for your kind words.

[@amokdesign]

Mr. Lewin, i find no words to say, you are simply awesome, whish i could be in your class, never touched physics and now i need to watch all of your videos, thanks for uploading and filming them! greets from austria! i need to check out the green light in the alps with my buddies! - thanks for your outstanding work! - ik wens u een lang leven

[@lecturesbywalterlewin.they9259]

+Philipp Laufgestalt Thank you!

[@mathbbn2676]

Really good teachers, both the activities and the explanations are very lively to learn with

[@searcherT]

Dr. Lewin please clear something up for me: when you rub the glass rod with silk is it that the silk becomes truly negative or is it that there is an overall decrease in the magnitude of positive charge. No I am not splitting hairs it just my hangup. As always I amazed at how well you are able to get your point across. Would of loved to have had your for what my school called Gen. phys 1 & 2 for majors.

[@lecturesbywalterlewin.they9259]

google "triboelectric series"

[@searcherT]

I shall, thank you

[@hridikkanjilal460]

We use I for current as French phrase intensité du courant, (current intensity)

[@electriciandallastx9182]

Thanks for the thoughts you have shared here.

[@ANOLDMASTERJUKZ]

We are so glad every day for the internet (one of man kinds greatest collaborations (ie) all of us) so we can watch some your video post every day, even though the hundreds types of jobs we have done through the years where we put physics into practice (ei) practical physics. It dose not matter to us how well we all ready know the subject matter, made ingrained by having to apply it, became second nature,. The point , we could listen to you Walter Lewin for ever, your sense of humor you apply in your teaching method, so entertaining. And they(your videos have proven to be an incredibly valuable refresher course for our current R & D obsession. By the way : #HelpRescueNetNutrality

[@lecturesbywalterlewin.they9259]

thanks for your kind words

[@ANOLDMASTERJUKZ]

For sure we want be friends with you, would love to be able have an in person discussion in some future space time.

[@ANOLDMASTERJUKZ]

Thank you for living ,you are true gift to the world.

[@kamyawilly9146]

Thanks sir for you decent demonstrations, you have inspired me a lot, Im also a physicist, and im working hard to be like you in this great discipline of physics.

[@lecturesbywalterlewin.they9259]

:)

[@gainiq1384]

Hi professor Lewin. For as far as i know, energy is never lost and can not be created from nowhere, if that's true, then what folows is that turbines will lose their energy faster while generating electricity? for example if we remove the magnetic field from around the conductor will a wind turbine spin for a longer time or spin harder?

[@lecturesbywalterlewin.they9259]

A modern wind turbine produces electricity 70-85% of the time, but it generates different outputs depending on the wind speed. Over the course of a year, it will typically generate about 24% of the theoretical maximum output (41% offshore). This is known as its capacity factor. If we remove the magnetic fields there will be no production of electricity and the turbines will enormously increase ther speeds. Unless there is a braking component built in, the turbine will then probably self destruct.

[@gainiq1384]

Lectures by Walter Lewin. They will make you ♥ Physics. Thank you professor for that fast and detailed response. I love to watch your lectures "full of life" definitely makes us all love physics.

[@EarlLedden]

Professor Lewin, forgive my half baked thought; with the earth's core being ( abundantly of) iron surrounded by a spinning earth, is there a flow of electrons or electromagnet created that could be used as an energy source?

[@lecturesbywalterlewin.they9259]

use google. No we cannot use that as an energy source yet.

[@karthikgs8024]

Sir with your vt of physics lectures I have fallen in love with physics

[@blackbox330]

Sir, Thanks a lot for the videos. They have cleared my doubts. For eg I tried to run a 5V motor with a solar panel. The voltage was 20V but still it did not run. Now I have understood that we need enough charges too.

[@lecturesbywalterlewin.they9259]

Excellent

[@hseverins]

Hahaha, die pruik van jou!? Net Bon Jovi !! Ik denk dat , als ík een vraag had mogen stellen , ik had gevraagd ; ARE YOU NUTS !? Prachtig hoe die tl buis oplicht! Fantastisch hoe jij dat uitlegt ………. Waren alle leraren maar zoals jij Walter! De uitleg , realiteit, en de humor zijn ongeëvenaard! Dat mag ik toch wel zeggen als groot fan 🤗. We hebben een nieuw kabinet ! Dezelfde leugenaars, maar met een andere functie ! Maar enigszins ben ik wél blij dat Dhr Robbert Dijkgraaf als minister van onderwijs, cultuur en wetenschap toetreedt! Dijkgraaf ken jij die persoonlijk?

[@lecturesbywalterlewin.they9259]

mijn antwoord would have been - YES I AM Nuts

[@diwashkarki8408]

love your lecture sir.they are just amazing.i cant figure out why some paper piece stuck on the comb..

[@debasishpanda2254]

Sir u re just awsome and the man full of knowledge .I wish to do my PhD under ur guidance it is my life biggest wish .

[@jayanthchintu9543]

sir may i know the continuation class of this and the class was awesome if i had a physics teacher like this i would excell

[@lecturesbywalterlewin.they9259]

+jayanth chintu start with 8.01x . all 36 lectures are on this channel.

[@peace152-x1g]

Why not English subtitles?

[@woodahkillah5583]

This was fun to watch I loved it

[@f4gbvit934]

I love you Walter Lewins

[@lecturesbywalterlewin.they9259]

cover all my costs for me and for my wife and we will come to France

[@f4gbvit934]

ok Walter, I 'll eat noodles this year and next one I'll call you :) it 'ld be so fantastic to see you and your experiments in Nantes 8-)

[@yawasar]

Walter can you do an experiment to detect the quantum charge q and the magnetic field M. q=4C/3X and M=500Vs/X. Planck' Constant=qM. The free space resistance z=M/q=375Vs/C=375 Ohm.

[@lecturesbywalterlewin.they9259]

piece of cake I'll do it in my next life

[@krishnakumararya8466]

@@lecturesbywalterlewin.they9259 u r more than awesome🤣🤣😂

[@jeevanshrestha875]

physics is very beautiful subject.....that i know after walter lewin lecture

[@arvildasgupta5938]

sir I faced a problem which asked " In free fall , air resistance is more effective in slowing a feather than a coin " we have to correct the statement

[@lecturesbywalterlewin.they9259]

watch my 8.01 lecture on air drag.

[@arvildasgupta5938]

thank you sir

[@syedahsan1537]

Sir is it in 8.01 or 2 I'm confused

[@lecturesbywalterlewin.they9259]

this was a special talk for kids

[@prakashsharad]

Sir, is there any lecture on cosmic rays I want to know it's origin and character

[@lecturesbywalterlewin.they9259]

search the web.

[@ballinosweety8902]

Sir u are outstanding your examples make easy tounderstand i inspire with ur teaching

[@lecturesbywalterlewin.they9259]

:)

[@piyushkumar6609]

Is there any other way to ensure the magnetism of earth other than using the directive property of magnet.

[@lecturesbywalterlewin.they9259]

question unclear

[@piyushkumar6609]

When we suspend a magnet freely then its north pole shows not direction and South pole shows south direction from this we concluded that our earth has also magnetic properties ... I want to know that is there any other method to prove the magnetism of earth

[@lecturesbywalterlewin.they9259]

@@piyushkumar6609 In principle there are many ways to notice the magn field of the Earth! one of them is the areas on Earth where there is Aurora.

[@piyushkumar6609]

@@lecturesbywalterlewin.they9259 Can we ask our queries from you through email???

[@DharasInfotech]

awesome lecture i have seen ever.

[@zoharavigal3517]

at 1:09:24 there is a rainbow on the fan! why is that?

[@lecturesbywalterlewin.they9259]

+Zohar Avigal I took a look. It's not a rainbow but there some nice colors. I don't know why they are there, but they are nice. Thanks for pointing this out.

[@zoharavigal3517]

+Lectures by Walter Lewin. They will make you ♥ Physics. hahaha that's interesting it's looks like the colors you get from soap bubbles or little oil drops when light go through them, maybe it has something to do with the camera properties :)

[@tirthpatel20]

ENJOYING PHYSICS..... GREAT!!!!

[@ishikawalia3407]

Why do opposite charges attract and same charges repel?

[@lecturesbywalterlewin.they9259]

google "virtual photons"

[@ishikawalia3407]

On searching this on Google, I found that it is written that virtual photons are real particles but on the other hand, it was also written that they cannot be seen or detected in any way because their existence violates the law of conservation of energy and momentum. I'm confused. Please help me with this.

[@aashsyed1277]

I love that even 5 years old are watching this . I am 9 years old

[@ansharora5716]

Sir can you please refer me a good physics book for high school ?Please let me know.

[@lecturesbywalterlewin.they9259]

search online -

[@shamsghani5709]

Nice sir

[@828So15th]

This lecture helped me more than any of the other videos with understanding magnetism. I actually took out my notepad and jotted down notes. I have a question about a story idea I have regarding magnetic forces, but I can't reveal here on You Tube. Are you willing to be contacted through your website? Thanks

[@lecturesbywalterlewin.they9259]

you can only contact me here

[@828So15th]

just realized the website is managed by someone else

[@kamrankumail9628]

Sir, I think some of the things are differently made and thought by a person depending upon the teacher and it's interest.

[@gainiq1384]

1:06:25 in a other lecture on electromagnetism professor Lewin writes on the blackboard "I" for induced current link kzbin.info/www/bejne/pHi0k3Ron9yejas

[@surendrakverma555]

Excellent explanation Sir 🙏🙏🙏🙏

[@lecturesbywalterlewin.they9259]

Thanks and welcome

[@harishkothari7441]

Sir you are legend and than also you are repling for our messages

[@curtisjordan9210]

what an awesome video!

[@rohansuyal5602]

wonderful sir

[@Soorya17-i7c]

Your lectures are great sir ❤️ but please can you tell me if that catfur was obtained by killing a cat or from a dead cat?

[@FearsomeGibbonofDoom]

It was obtained from a live cat, and to this day that cat is still furious.

[@deepakjoshi823]

Even kids attend his lectures! 😆😆😆🤗🤗😘😘😘🤗🤗🤗 These kids might be of my age now! 😂

[@dumbledor22]

You said professor that you don't know the reason why an "i" is the symbol of electric current, well, isn't it simply the initial of "induction"?

[@lecturesbywalterlewin.they9259]

no

[@Hisham_HMA]

it comes from the French intensité du courant, intensity of the current

[@kamlakunwarjhala2381]

Professor i want to ask one question if you remember how many indians were there in your lecture hall

[@lecturesbywalterlewin.they9259]

my guess is 21.3

[@aura7728]

Loving physics......

[@harishkothari7441]

It show that you are true legend

[@physicsinhausa6760]

Best xplaination wow

[@himanshusir3024]

Awesome👍

[@mikeypeinado383]

i think main lesson here is : in order to be a scientist grow ur hair out crazily and look like a crazy

[@divyapaliekar7680]

I love physics

[@ratnasaxena4754]

You are looking smart in this shirt

[@areyouavinalaff]

lol. only the ultimate physics nerd would use a compass to get around new york... although it makes perfect sense.

[@sineads.9920]

i hated electricity before i watched this lecture

[@rasamayacommunication1226]

Why are the colours present on the fan !! ?

[@rasamayacommunication1226]

Is that due to humidity reflection from the bulb ???

[@lecturesbywalterlewin.they9259]

how many minutes into the lecture?

[@rasamayacommunication1226]

Entire 1.41 minutes

[@rasamayacommunication1226]

I always that colour doubt not only on that fan even on a normal sunny day when we view a window from certain direction you observe window border glass and wood in green colour !! Why is that so

[@lecturesbywalterlewin.they9259]

I have to know HOW MANY minutes into the lecture.

[@Saurabhsinh_chaudhry]

Rose is now 22 or 23 years old beautiful girl.....

[@areyouavinalaff]

13:30 fatal error! north pole is not attracted to south pole. and south pole is not attracted to north pole. in truth the north pole is attracted to the north pole, but since the magnet is physically in the way the north pole can not move towards each other any further. you can prove this by alowing the magnets to slide side by side.... north always goes to north and south always goes to south. one magnet pulls the other and the fields of each try to combine into one field but they can't because the physical magnet gets in the way. sorry Prof Lewin, you wrong.

[@lecturesbywalterlewin.they9259]

Every magnet has both a North and a South pole. When you place the North pole of one magnet near the South pole of another magnet, they are attracted to one another. When you place like poles of two magnets near each other (North to North or South to South), they will repel each other. www.google.com/#safe=active&q=why+do+magnets+repel+each+other

[@lecturesbywalterlewin.they9259]

yes this is a laugh

[@JeanMullers]

Best part ever 0:31

[@lecturesbywalterlewin.they9259]

Jean Muller Thank you \\/\////////@lter

[@systemicxdesign]

Give thanks.... TESLA!

[@funkefact822]

Sir I wont to study physics in all my life

[@piousalhamdulillah4078]

Yes Sir I got it

[@hseverins]

Some people can not even Think with electricity!!! Whahahaha die is goed …………. Hoe ben jij in De wereld draait door gekomen?

[@lecturesbywalterlewin.they9259]

ik was in Nederland en daar hebben ze me benaderd