Induction - An Introduction: Crash Course Physics #34

In this episode of Crash Course Physics, Megneto helps Shini explain what induction is, how it works, and why magnetism is so seemingly complicated.
--
Produced in collaboration with PBS Digital Studios: / pbsdigitalstudios
--
Want to find Crash Course elsewhere on the internet?
Facebook - / youtubecrashc. .
Twitter - / thecrashcourse
Tumblr - / thecrashcourse
Support CrashCourse on Patreon: / crashcourse
CC Kids: / crashcoursekids

[@crashcourse]

We made quiz questions to help you review the content in this episode! Find them on the free Crash Course App! Download it here for Apple Devices: apple.co/3d4eyZo Download it here for Android Devices: bit.ly/3TW06aP

[@Chloe-kf1lh]

Lately I've been seeing Shini and Hank more than my own family

[@geeway5923]

same

[@tiamatmarduk8406]

Is that by choice?😂

[@madladdan]

Leaves school: Yesss finally I'm done thank you Crash Course you've been good to me! Starts engineering at uni: Aight I'm back...

[@kimaegaii]

I sped this up to 2.0x speed and I started emitting flux around my entire body. All kidding aside, as a beginner even this is seriously helpful. Thank you.

[@erikziak1249]

It is easy to watch if you know what Shini is talking about. However I imagine what a mess it must be for someone with zero background knowledge.

[@TheMahjohng]

Erik Žiak yeah I haven't studied physics in a while and had to repeat sections a couple of times.

[@Y2KNW]

I barely passed grade 11 physics and got lost almost instantly. :P

[@thijsiee2]

It goes way, waaay too fast for me, even though I have a good understanding of the material. The material is presented too quickly. Some moments to think about the material would be better, to actually internalize what has been said.

[@erikziak1249]

That is why it is called CrashCourse. Feel free to use the pause button and rewind as often as you like.

[@TheMahjohng]

Erik Žiak yup 😂, used that pause button at every formula

[@ChristianGonzalezCapizzi]

I can't imagine anyone who hasn't studied this before learning anything at this speed.

[@fridaaa0]

ikr, they're good summarisers for rehearsal though

[@ritvickrocks]

just revising

[@user-nh7xb9ps4t]

It is so fast that it confuses people even I learnt about it before. Eventual it is not the speed but the way it is presented which is just to the conclusion without showing how people discovered it step by step

[@dayzyrules1]

play in .75 speed & pause to take notes

[@ramlahassan9761]

The reason why I love crash course is the fact that it doesn't waste your time (in most cases)

[@KingsleyIII]

We're all flux'd.

[@32heretic]

Straight up studying electronic engineering and I thought this explanation is fast, feel sorry for anyone who doesn't have a background in this.

[@32heretic]

Good explanation just talk slower

[@MrThegreatViewer]

Anyone cramming for a physics test right now...?

[@hanro50]

Yes

[@realdvgarg]

freakin MYP makes us have a 3 sciences test together

[@u13613to]

Kind of same here :') , electronics test*

[@rangkara7201]

Me every physics test

[@joleareed4639]

James Anderson 🙌🙌

[@mannyaustinanderson9608]

I'm going to end up viewing this video more than once

[@churchboy4609]

Try changing the playback speed, it should be an option in the video settings

[@CharlesVeitch]

I am still looking at my kitchen hobs with confusion after this video

[@duhhuhduh]

I don't know if anyone else picked up on this bit, but she pointed out the opposite of what she was talking about. She said that you can use the right hand rule to know the direction of the current based off of the induced magnetic field, which is right. But, she got the direction of these fields wrong in the second half of the video.

[@johnnyace1300]

Yep! In very poor taste, I rely on this chick, she should have personally edited the video herself and she would have picked it up easily. Crash course wasting my time again.

[@DM-ce6su]

The mistake is at 6:11 for anyone who is wondering. Way too many mistakes in this entire series

[@xlsmafia]

@@DM-ce6su Thank god I thought I was going insane

[@frede1905]

@@DM-ce6su No, it is correct. I know that the magnetic field generated by the current is in the same direction as the magnetic field of the magnet (over the north pole). But the magnet is moving down, so the change in the magnetic field is in the opposite direction. And so you have used the Lenz law in the correct way. However, if I haven't made any mistankes, then I think the example of the loop moving out of the magnetic field is wrong. The change in the magnetic field (flux) is pointing up, just as the magnetic field generated by the current. And that is violating Lenz law.

[@Paprikaa81]

It is right learn physics properly before judging her

[@jamilladambo]

This is very useful when you want a quick review of your course before final exams not for you to learn afresh. I find review videos very helpful

[@jasonsterlace1369]

At 6:32 the current is backwards. I think it was backwards earlier, too. I really like these animations and explanations, I wish PBS would fix the errors.

[@modelsin3044]

Wait so crash course is targeted to high school physics students but then they are sponsored by prudential which is aimed towards seniors planning for retirement??? Not the best place lol

[@slowgaffle]

best time to start planning for retirement is when you're young!

[@aloevera1269]

This is an excellent opening. I get some knowledge about the topic which makes me want to read more in depth about then. After reading in depth, I can come back to this and rewatch it, and understand it much better. I love how there's no Time wastage. Hate off to y'all

[@joshkaye5303]

Needed to slow this video down to 75% speed to understand it.

[@erasmith2048]

Really helped slot. Thank you crash course. Lots of appreciation .

[@rockyjoe3817]

People complain about how she speaks so fast that no one can collect what she said . For god's sake just turn on the CC English and watch it at 0.75× speed.

[@leolehrer2408]

Thank you so much! Having an exam soon, this course really helps.

[@stephaniej9714]

Thanks a lot for your videos

[@Sora-ce1zx]

6:32 I think this is the opposite. The mark Xs indicate the magnetic field goes from the front to the back of the screen. If you move the loop like this, the total magnetic flow penetrating the area of the loop decreases. So you can guess the current will flow to create the magnetic field to oppose this decrease of magnetic flux. In this case, the current should go in the opposite direction as shown in the video. Please correct if I’m wrong.

[@Teo117]

This stuff is AMAZING!!!! THANK YOU 🎉🎉🎉 I absolutely love this information. You are extremely good at this. The information can be troublesome to explain simply, but I always end up understanding. Thank you 😁

[@sunnisukumar]

Good review with helpful and pleasantly colorful graphics!

[@alanday5255]

I love this video. I wish you would do one on the application of Faraday's Law on automotive ignition coils.

[@orzini7522]

You help me so much, thank you ,Love you⁦💓💓

[@default0321]

Physics

[@crashcourse]

YES!

[@DrewKF]

+CrashCourse Woo! :D

[@kingviper5700]

That's what I say every time I summarize

[@xyzxyzuvwuvw7633]

zero flux

[@kploo4906]

Thank you for your work👍. It seems pretty fast and no time for thinking to thoroughly understand well such a technical things unless the guy was very well in this aspect. Anyway thank you again for trying made it simply for me to understand😁

[@cooldiys3477]

Thank you so much, there are a lot people complaining in the comments but I am honestly so grateful that u do videos like these, as they are so much more engaging and I get a lot more out of them than my textbooks

[@rushvi1611]

thank you for the video, was a great help:)

[@epicfailled]

Is the direction of current at 6:30 false or did I have a brain malfunction? happens sometimes...

[@sohaibbaig248]

wondering the same thing

[@adrianaselena14]

It's false. She said the generated magnetic field points upward so the current flows clockwise, but what she should have said was that the change in magnetic flux is pointing up, which means the generated magnetic field is pointing down, thus a clockwise current rotation.

[@metitusable]

@@adrianaselena14 Shes just reading from a script and got it wrong.

[@Uzukavil]

Awesome episode! :)

[@ziyadqezbour1502]

thanks for the video you're the best

[@suvarnaingale6903]

You tell n make me feel it's easy to understand thank u

[@georgemacidy1316]

Great video. Thanks.

[@enna...]

Every time she says ‘emf’, change it to “voltage” or “potential difference” in your head, they’re essentially the same and it makes it MuCh easier to understand!!

[@jbeanp1]

Yes that’s one of my biggest pet peeves in my physics class; note I’m top of my class but wording is so unnecessary sometimes

[@jadeg1154]

That’s actually not true. You can think of it as the voltage across a battery but not just as voltage because you can’t calculate the voltage when the electric field is “loopy”. They’re similar but not the same. Emf is the line integral around a closed loop but voltage difference would be zero around a closed loop because it’s path independent.

[@daBuzzY90]

@@jadeg1154 The potential is just the gradient of the E-field. Therefore if the curl of the E-field is non-zero, a closed line integral would therefore generally also be non-zero.

[@pedrogaleano6722]

Maybe that will be helpful if you want to grasp the idea, what essentially they are not the same, and it is good to know that when you are deep into studying -let alone before sitting for the exam!

[@enna...]

Pedro Galeano I’m aware they’re not the same, but for basic understanding it’s a great starting point if you don’t have the overall idea - I just found it simpler to understand it this way before going into technical differences!

[@Voidward]

I remember checking these out a while ago. This still kind of feels like someone reading off a script as fast as possible rather than actually attempting to explain things. Sadly, I was actually interested in this topic a few days back and as a newbie to this, would have liked a simple explanation of how to calculate the size of coil and magnet needed to produce a specific voltage, but this really didn't help me in any useful way. I'm actually better off just reading the wikipedia entry because I can at least read that at my own pace and go to the relevant sections. This really should have a more visual presentation format.

[@ruweydaaden2329]

try writing down.study.then y will enjoy the video

[@adubey248]

WOW I love this video

[@acexperiments475]

Great video

[@pedrogaleano6722]

Very helpful!

[@joejohnson6209]

I love that Magneto makes a cameo. The fact that he is a HeroClix figure makes it even better!

[@alminabajic4684]

this is just what i needed

[@zhen3356]

Thoroughly explained!

[@ac30428]

At 6:33 isn't the current direction in the wire the opposite of what it should be? Downward Flux is decreasing, so induction wants to increase downward flux which means current should be moving clockwise

[@ezramiller9150]

Love your videos! Quick question: What happened to the negative when you plugged in x over t (velocity) into the equation for EMF?

[@SIDEKICKONYOUTUBE]

my nose started bleeding @ 3minutes

[@JossinJax]

LOL

[@gavinwieland3707]

This video is really educational.

[@kalpanashedthy3101]

💙LOVED IT❕

[@madalitsokasongo6132]

These videos are really helpful... Y'all do a great job... Big ups to the team👍

[@lupevinado3087]

thanks thanks thanks so damn well explained !!!!!!

[@jscotthatcher380]

today i learned i am terrible at maths but still enjoy these videos.

[@antonioarreola7994]

needed this for my final last week 😢 good video though 😊😀

[@ntana4589]

Well I understood completely. Thanks Shini!

[@phoenixfromtheashes]

5:54 Anyone else confused by her definition of the right-hand rule here? She says that current is the direction your fingers are pointing, but the graphic says that current is the direction your fingers are curling.....

[@The97gtrs]

It doesn't, the graphic is wrong (again)

[@IIGrayfoxII]

Hard drives that use a rotating disk are called hard drives. Ones that use memory modules are called Solid State Drives

[@ibrahimx9560]

love your vids here in crash course 😍😍😍😍😍😍

[@terryi8892]

Clear narration.

[@sftaxitaxi1334]

well done

[@hussain9413]

love it

[@cmopmoemo]

This makes a lot more sense if you describe Faraday's Law as e-induced is dø/dt. For a magnetic field (that doesn't change as a function of space) Ø=B•A, as you said. So Emf=dø/dt=B(dA/dt)+A(dB/dt) by the product rule. So a change in magnetic field with respect to time or a change in area with respect to time induces an Emf! This is an easier way to see what's going on for that type of B-field.

[@georgeruellan8593]

Thank you, big help! :D

[@tabrezahmed1000]

Where did the negative sign on phyb when they substituted it in the emf equation? 6:49 and 7:28

[@adubey248]

It is the best video to learn

[@vanshajgandhi6845]

Please do a video on semiconductors and transistors and wave optics

[@Eyenn_n]

I graduated high school in 2015 but this video wasn’t made till 2016. If the crash course physics series could have been made a few years earlier, I might end up at a much better place (college, grad school, etc) now. And for those who are watching this as you are taking AP physics, you lucky ducks.

[@crushcollegechemistry]

Love the cartoon Magneto!

[@rishabh645]

Just love your unique accent

[@rohakhalid1846]

I'm watching this at 4 am and I literally have my physics exam in 4 hours.

[@healthyauthentic7453]

omg so cool!

[@engineer_Abdullah_Majid]

thank you very much

[@crashcourse]

Well, you're very very welcome :) - Nick J.

[@perpetualpolymath5961]

That name...

[@engineer_Abdullah_Majid]

Mo Killem hhhhhhhhhh

[@brian-nx8ge]

my worst topic - thanks CrashCourse!

[@tahoon2009]

EMF vs V Equation deduction illustration was so beautiful

[@rasheedaz7059]

I know all about this from my physics teacher at school, except Lenz’s law. And I was suddenly aware of how fast she was going through all of this. I could not understand the rule, nor the experiments conducted to conclude it.

[@alejandroxalabarder7940]

the right hand rule also called screw rule is a three dimension rule (x,y,z), so having the hand just quiet as she does cannot show anything. What she explains in fact can be done with the left hand as well.

[@mikeyallen6758]

is there going to be another crash course on advanced physics or will those topics be covered in the last few episodes?

[@vatsalgupta9460]

At 2:50 shouldn't she say parallel and not perpendicular (cos90 is not 1)

[@marianauroz240]

Vatsal Gupta Yeah I thought the same. Since cos 90 would be zero how is she taking it 1?

[@fatherharveymisty7863]

it's not even cos, it's sin

[@peterlamont647]

If you talk fast enough, you can fool _most_ people, _most_ of the time.

[@juhisangtani5820]

Yeah Everytime she used cos90 equals 1. Equation was equal to 0. 🙄 This messed up my concepts

[@CS.319]

Thanks!!. Thanks 💓

[@morenikeadekoya5682]

Could you please do one on Gauss law?

[@ratssss45556]

Best video for electromagnet!

[@bluiflip]

I think her “right-hand rule” explanation is backwards to what is being displayed.

[@jonathanling2421]

Haha. "An Introduction" That's funny.

[@user-xh5ps4xg7g]

thank you

[@ringocash6143]

At 2:52 the magnetic field and area of the loop should not be perpendicular but it should be parallel so that cos(0)=1

[@PeacefulAnxiety]

So is there an estimation on when higher ed physics will be? I know on patreon John said it was one of the projected series for 2017.

[@fakjbf3129]

Oh for a second I thought this was going to be Crash Course Philosophy

[@Lightning_Lance]

Me too. I was like "didn't they do this already?"

[@Paprikaa81]

Why

[@SpartaSpartan117]

Thought it was titled Introduction- An Introduction

[@ozzyg1964]

Hello Crash Course team. If you're reading this, I hope you'll someday do a crash course on art. Not on how you paint art, but how you interpret a painting or a sculpture, and maybe define and explain the transitions in art periods. The composition of the series could be historical. Start off with a retrospective from the renaissance where the perspective was introduced in the painting. How baroque emerged. Look from how impressionism involved into expressionism. How surrealism expressed the subconscious. Because art periods are often linked to historical events or scientific paradigm shifts. Surrealists were very inspired by Freud and his theory of the subconscious for example. It was just an thought or suggestion. I mean, your viewers obviously have a very sophisticated mindset, and this could be very appealing to them. Please reply and thank you for taking the time to read my comment :)

[@verdatum]

Crash Course Art-History would be nice. I know the idea has at least been thrown around.

[@TheMitchy27]

Ozzy g yeah i could see CC Art coming and it would talk about art, music maybe a bit of technology and famous artists and composers

[@tnttiger3079]

If you want something like that, check out the KZbin channel Nerdwriter. Thank me later.

[@zcwan5349]

magneto would be proud

[@AceNallawar]

please make videos for semiconductors and electrical instruments

[@cornelioescipion9930]

Sorry, Do you know why Faraday labeled it as "INDUCE current" or "INDUCED magnetic field"? I mean Why he used the term "INDUCED" instead of "Transmited" or "generated" or "created" or "reflected" or another term ? In Phylosophy Inductive method is in one way but in electromagnetism "inductice current" is in two ways so this term (INDUCE) isn't exact with the physics. Thanks for your answer.

[@dashamm98]

can someone find me a link to practice problems related to the physics lessons on this channel please?

[@euyoro4619]

For whoever is confused. I watched the video 3 times and have fully understood it. Ask me anything, I'd be more than happy to help. And a 5:48 she used the wrong fingers for explaining the rule. It's suppose to be curling finger, either clockwise or anticlockwise, then the thumb will show the direction of induced current.

[@brigham1465]

She says the induced current goes clockwise and counterclockwise, but doesn't say relative to where. For someone looking down from above clockwise IS counterclockwise :(

[@kerron_]

Good videi

[@alejandrobecerra3698]

I believe at 2:55 you said that if the angle from the perpendicular normal to the loop and the field are perpendicular then the flux will be max, however its when they are parallel, correct me if im wrong

[@mohanadebrahim1692]

In the animation at 6:32, I think the direction of current isn't correct. It flows in the opposite direction.

[@khoapham3066]

I have a question about the math equation between the emf and magnetics flux. When i look at the equation, the magnetic flux is directly proportional with the emf, but why did u said that when magnetic flux increase, the emf will decrease?

[@alexanderhugestrand]

If I get this right, a coil must resist every change in current since the "neighbor wire" (the same wire, but a different turn) induces a current in the opposite direction. It seems to me like there should be an energy loss any time you use a coil. Is that right?

[@ImranAhmed-sc1qe]

I hope one day you make a crash course on accounting Hank

[@zeynep8152]

i loved how magneto carries the magnet XD

[@holyspiritofgodinperson6957]

Nice