Ampère's Law: Crash Course Physics #33

[@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

[@mandyberry2500]

The fact that this series continues to be useful for my college physics classes says something

[@CODandponies]

no matter where i go calculus finds me

[@zuzusuperfly8363]

It seems like you're finding it, not the other way around.

[@CODandponies]

Zuzu Superfly ya I suppose I am

[@GoatFriends]

CODandponies two objects in a gravitational field attract each other with equal force. Maybe calculus is the same for you.

[@hussnainmuhammad2]

@@GoatFriends but they never come close to each other until external force acts, it's the same force of exams which help him to go closer to calculus

[@hussnainmuhammad2]

@Strawberry Dobreva lol 😂😂😂

[@danferno]

The animation at 5:15 actually shows the opposite of the right hand rule, doesn't it? There seems to be a mistake.

[@LARRY113Z]

Daniel FN Oh yeah I see they're both going upward so the magnetic fields should be going counterclockwise.

[@LARRY113Z]

Dheeraj Dhobley Its closer to 5:19. The currents are flowing upward.

[@Dota2funny]

and i was like, is my university wrong?

[@crashcourse]

Hmm... I'll have a closer look this week and see what tripped us up. Thanks for the heads up. -Nick J.

[@lancelovecraft5913]

Yeah it was. I guess they were using a non conventional current lol

[@kylewilzon8612]

I must have watched this 30 times. I finally understand everything. It only took 3 years.

[@janneusmaala6414]

Just had an advanced electromagnetism course final. It's always kind of amazing to see how simple fundamental physics laws really define the core of our understanding of the world. Great video!

[@RossMilligan]

They really need to add an annotation at 5:14 explaining that the arrows of field direction are wrong according to the right-hand rule, really messed me up for a second there.

[@HayDayEveryday]

You are pretty dumb! I didn't even realize that! As she was pretty much speaking through all time.

[@msquareddd]

For 5:16, there’s a problem with the direction of the magnetic field. It should be CCW.

[@danielmachuca3650]

Crash Course, I believe there is a problem with the direction of which the magnetic field is going at 5:16. If the current of the wire is pointing up, shouldn't the magnetic direction be pointing counterclockwise? I hope you can fix this. Thanks

[@oscarsmith3942]

Just want to thank you for showing the integrals rather than skipping the math.

[@megableful]

This series is so good. I definitely need a refresher on elec&mag- I hope this series goes on to cover all of Maxwells equations! Perfect speed, perfect animations. I wish this was around when I was learning it for the first time!

[@dumbxyz]

I really like you guys for adding subtitles because it help non-English speakers to understand it slowly ... thanks!

[@amandamoore2868]

This entire series is helping me review for my finals in college physics! I will continue with this series as I progress into my physics Waves class to get ahead :)

[@quemsereu2009]

I tried understanding this in school so many times, and this video made it so simple ! Thank you CrashCourse. The presenter is great, i have a huge problem with math/physics and the the way you guys teach really helps me. Just wanted to say thanks for the great work. Btw, english is my third language, so my grammar is not that good.

[@fossilfighters101]

+

[@ava1002]

Your grammar is pretty good, better than half of the US population

[@Kirihere]

Ava exactly

[@zarboov88]

Pretty sure that the arrows of the field direction in 5:14 are backwards.

[@sticky170]

zarboov88 yeah

[@ELYESSS]

I thought I was going crazy

[@kellys1458]

A shame. Hope they correct it. (They did get it correct earlier in the video @1:33)

[@sotiqa77]

hubj

[@alexChook]

Agreed

[@markholm7050]

The animation at 5:24 also gets the right hand rule backwards, as well as the one just previous.

[@jollynass6143]

My first language isn't English and i am not studying this but i find it interesting to learn and know about new and amazing things threw this amazing KZbin channel. thank you!!!!

[@samuelmccay4092]

Today I learned precious little about mathematics, but I did learn: 1. Magnetic force causes wires to torque when a current is put through it. 2. The math behind this action is known as Ampere's Law. 3. The Right-Hand Rules are mnemonic devices created to help consistently identify the direction of magnetic forces. 4. The torque generated by these forces are the basis behind electric motors. So I didn't understand all of it, but what I did understand was valuable.

[@RichardKCollins]

Please do not say "It gets very complicated, very quickly". Rather say, "It will take several or many steps, but none of them are impossible, or even that difficult. Faced with many steps just pace yourself and do not give up." Please do not say things to elicit feelings of hopelessness. Or to imply that you are much smarter and "only professionals can do this". Eventually the AIs will have memorized all these things and they will help recall, simulate and calculate the details exactly and precisely. Using the computer is smart. In work and jobs, getting things done right is often better than memorizing formulas. Richard Collins, The Internet Foundation

[@MarkGerads]

At 7:20, the forces are shown correctly, yet actually result in counter-clockwise motion. The clockwise motion at 7:30 came from the unexplained reverse of the magnetic field.

[@YoO-G]

Thanks crash course! I was struggling with the topic as I missed it's lecture, But now I am confident about the concept because of the visuals😊

[@vgfbestuur9565]

You explain things so well. Its all so clear!

[@VR_Wizard]

Minute 5:19. I was very confused about the pink force file and how it is related to the yellow field lines. After minutes of hard thinking I found it out. The space between the two wires is important as well as the direction of the yellow field lines in between. If the field lines of the two wires point against each other (parallel current) then getting closer together reduces the area where the yellow field lines point straight against each other. So reducing the amount of field lines in completely different directions is the goal of the two happy wires.

[@scienceandmind3065]

Thanks Ampere!

[@mrfortniteballer]

Can you make a Calculus series? I am really struggling with it and these Physics videos have helped so much with Physics! Please reply if you agree

[@tmr9999]

Give the Khan Academy a go mate: www.khanacademy.org/

[@mrfortniteballer]

tmr9999 Thanks! But I think it still might help to have a crash coarse calculus...

[@azubeyene9588]

A lot of the mathematical equations/concepts she used in this video are derived from topics late in Calc 3, so idk how much Crash Course can teach you, but if you want a better understanding of Calculus and how its used in Physics, I recommend Professor Leonard (on KZbin)

[@redx589]

A Math series would definitely be a good idea.

[@lahariboddu4358]

Daniel O’Connor The 2nd and 3rd videos in this series are of calculus

[@ColossaLXGamingHD]

For everyone that watches Crash Course and finds it too complicated, these videos just give a very brief summary of physics topics. If you actually want to understand in depth, buy a textbook or also visit places like Khan Academy or Isaac Physics.

[@bernadettebouchard415]

I just fell in love. Wonderful explanation! Amazing visualization! Best explanation I have ever found online!

[@ifu676fr]

I am an electrical engineering student . and I am very thankful for your videos

[@zeustheboerboel3794]

Awesome animations! Really helps to build the concept. Thanks a ton

[@Zeekar]

This is the very first time I've come away from a crash course actually feeling like I newly understand something I've wanted to since I was a small child (how the heck electric motors work). I'm not sure why I never just looked it up, but that's besides the point. Thanks!

[@Amanueel]

amazing channel, i just discovered it. And i have watched so many vids of you, its fun and easy to understand every thing that is said in the videos. Very good channel!

[@peteroconnor5537]

Easy to listen to and easy on the eyes.

[@NjniaVanDerWald]

can we have a course with basic math liek what 1 plus 1 is? i feel this accomodates my abilities in this subjects more.

[@Kenlimepie]

Njnia van der Wald crash course kids?

[@NjniaVanDerWald]

Kenlimepie hey, i am an independent, grownup woman! I ..., welll, yes, you're right. :D

[@charlenechan7504]

Hello! I hafta say that I love the videos, I can finally learn something without groaning all the time, well done! I was wondering if you guys could do Linguistics as well?

[@ronbessler1271]

The videos explained and animated wonderfully! But it is to fast to actually understand. I personally see these videos in a slow motion mode and still find it not easy to understand. I know you wanted as to see it in 10 min but maybe it would be more useful to have longer videos with a deeper understanding. Honestly it would be a dream come true to have 40min video on a subject with examples nice pace of talking and your wonderful explanations and animations.

[@kylemandla1543]

Thank you ! Your videos are bloddy good!

[@Vidyaasshh]

0:12 I think that man got jaundice

[@allaboutworldfood]

why you make things easy. taught us as our tutors did.(4 Year)but i respect them still. I understand now the Ampere's law in a good and effective way.

[@muzammilhamas6488]

Just brilliant, totally brilliant loved the teaching method and the graphics.

[@hvincent1106]

I am really glad you did all these videos. I really wished i had access to all of these when i was a student. Kudos to you, and subscribed!

[@AnyaXPsyduck]

Gosh having a visual representation is soo much easier than figuring out from equations. Also make me realized why B is assumed constant for all ds and thus can be taken out of integral.

[@fernandocadena_]

Amazing lesson! Congratulations from Brazil!

[@AbhishekSingh-lb2kp]

Great animation..and explanation. Well done.

[@Chathumal2011]

Nice explanation with animations..

[@noreaction1]

More videos on electronic and magnetism please, thank you

[@jeremypaton4300]

When you guys at Crash Course have the time, can you do a Calculus Crash Course? I feel like it could be very useful to many, and could be pretty entertaining to watch. Also, some math teachers can be terrible, and I feel that a Crash Course could make up for that. A Crash Course Calculus, in my opinion, could really help out the world.

[@jonathanschossig1276]

Jeremy Paton They did two lessons on the subject at the beginning of the course.

[@alexl6856]

Could guys do some videos on Music Theory??

[@abishekraju4521]

yeah man . I want that too.

[@flamedragon07]

They have one on the science of sound waves and music if that helps.

[@jebbush8061]

Damn I'm starting to like physics with this person

[@Tfin]

The mathematics can get very complicated very quickly, and we've just blown through the formula too quickly to follow, but let's say we're explaining it while piling on more math even faster.

[@navtejsingh6351]

No words for you mam u r best in physics

[@himalekhamunukoti8079]

Awesome video thanks for making it easy

[@FuZandy]

Great video!

[@Kabodanki]

I feel dumb by watching this, looks like my shutdown when I see an equation

[@infyprog]

oh xD same here

[@alien9279]

Yaaaa. Same :/

[@chuckopop8096]

Thank you to learn us so much

[@strawberryandpink]

I had a physics test on this topic a day before this was uploaded rip

[@maro8D]

Great video! But you got the second hand rule wrong. 7:10 You should point your hand (I prefer index finger) to the direction of CHARGE VELOCITY and not to the current flow direction. Since inside the wire electrons are moving in opposite direction to the current flow, you should point your index finger in the opposite direction than you showed in the video :). This way your example with two wires will make sense.

[@piyushgoyal7583]

hey can you please upload rest of the series of this physics crash course plz plz....

[@shivamchaudharyhere]

I love ur t-shirt. by the way ur way to express is quite awesome

[@Nightlurk]

My little head enjoyed watching this despite my big head constantly telling it to quit it out...

[@SanJose_Panda]

I really wish I was smart enough to understand this better, ha ha. Never was very good in physics, but this was definitely helpful!

[@shangobashi]

Excellent.

[@d-m.n_--2]

So at this rate alternating current that runs the motors, and therefore Tesla, are the next video. Cool! from which point we could go more into DC and the findings that came around that time period.

[@ajeuscher7988]

Hey quick physics question for the presenter and/or anyone knowledgeable in comments. I am in a senior level undergrad E&M course and we use a slightly different formula for Ampere's law, Integral of B(vector) dot dl (vector) = mu naught Ienc. Are you guys just approximating the dot product as cos(theta) and if so why are you? Also thanks a bunch for the timing of these videos, its been perfectly lined up with my E&M class

[@markholm7050]

Aj Euscher I think you answered your own first question. As for your second question, the videos assume an audience that is just barely able to grasp very basic differential and integral calculus plus a very tiny amount of trig. Expecting the audience also to understand vector multiplication is beyond the assumptions. In the comments to the first videos in the series, there were a lot of complaints about even the extremely simple calculus used.

[@ajeuscher7988]

Mark Holm that's what I figured, I just had to check if there was some other reason why besides just reducing the mathematical complexity.

[@Duge6124]

the theta is first mentioned as the angle between the B-field and current (2:09) and then later on mentioned as the angle between B-fields at different points of the loop. I don't know which one is correct

[@mitchellapple9184]

I'm a smart guy, I swear. I was pretty good at physics in high school, got an A. This stuff is intense, it's much more difficult than any other crash course subject. I just can't do these... I'm still in love with our host though. Brains and beauty.

[@hypro999]

Just a heads up, but you really should have used dl in the equation as opposed to ds because otherwise what you could confuse viewers with the Gauss law for magnetism in which case the surface integral of B.dS (sometimes also shown as B.dA) should give 0. dl because we are considering a differential element of length of the ampere loop. Correct me if you disagree though.

[@DLockX]

When you add vector calculus to this... The difficulty to understand this just blows up! lol

[@costbart]

unless you mean electron flow direction (which would only complicate stuff) the field should be turning in the opposite directions. It's called right hand rule because you use your right hand, Seems like you used your left.

[@abishekraju4521]

try pausing an taking notes for those who find the video to be kinda racing. It really helps.

[@pup11074]

Can I just say after how long I've been waiting for crash course physics vids and then to discover this amazingness! finally!!! Also delighted I like the host! I'm thouroughly pleased... ¦-)

[@EdwinRamirez-fk9fn]

excellent. thank you

[@sadaque7490]

Thanks from Perú

[@anuraghooda8439]

At 2:08 it's written that theta is the angle between current and magnetic field, shouldn't it be the angle between the element ds and the magnetic field?

[@ameerhamza4816]

Yes it should be the angle between ds and magnetic field! There is also another mistake in the video 5:14 they show the direction wrong

[@dineshrai2658]

very nice

[@Mohit-ir5xo]

started following your channel and your dressing style.

[@therapist2852]

surely, this is all i need to pass my test

[@minaf6311]

So useful!!!❤

[@jasonnankoo1567]

You are excellent. You are the best. I am so impressed that you are a beautiful, intelligent woman with an amazing art for teaching. You are number one. Your information is so well organized, and you present it amazingly.

[@SotraEngine4]

"current that continuisly flips" - illustrates with a battery 7:28

[@Hacken594]

at 5:20 the direction of the magnetic fields are both wrong.

[@zakirhussain-js9ku]

I think charges are surrounded by flux of microscopic particles. Flux of like charges add up while Flux of opposite charges relocates. On closing a DC circuit electric flux in the conductor relocates by exiting the conductor radially due to opposite charges on both ends of conductor. This establishes an electric field in the conductor which exerts force on charges. This force moves only electrons as they are lighter & loosely attached at the surface of conductor. This establishes current in the conductor. After initial increase the electric field becomes constant at which flux leaving the conductor stops. Initially moving & changing electric flux induces circulating & changing magnetic flux around the conductor. As electric flux stops, motion of magnetic flux also stop. On achieving equilibrium electric field inside conductor and current flow becomes constant and a circular static magnetic flux of constant density is established around the conductor.

[@tayyabzaman2661]

Miss home tuition doo gi😂😂😍

[@user-mg2td5id6m]

Hey could you do a crash course on grammar? Like going through the basics that would be helpful especially for students who are about to take the SAT ACT and PSAT

[@yusufhanna6554]

We will, in my opinion, win today

[@pearseh7640]

are y'all doing radioactivity/nuclear physics and optics?

[@bharathjs3171]

it is very helpful

[@magmagon5572]

my laptop doesn't have a fan :-) also the original experiment is using DC current am I correct? The electric motors on the other hand use AC motors?

[@Triumph263]

I wish Crash Course had a series on math, when I was in school I always had trouble concentrating (ADD) and writing fast enough to keep up (my hand writing at 18 is worse than that of the average five year old, and if I write faster it only gets worse) and because of this the school would try to put me into "easier" classes, the problem was the "easier" the class the more difficult it was for me to concentrate and the more I fell behind. I graduated high school with what is the equivalent of a sophomore grade level in math. I am an intelligent person, I can understand what concepts are trying to be explained with math but I can't actually use math. I am a huge science nerd and am going into computer science but I still can't understand almost any math; I strongly believe I am capable but trying catch up in math from where I'm at is difficult. I would love series about math for this reason. So I would love it if you guy's did a series on mathematics but if not could someone point me to a good resource for it?

[@osemudiame123]

Triumph263 khan academy! if you are getting bored or distracted then just force yourself to not do that for a week. I used to have this problem, and if you simply force yourself to do the monotonous things for some time they get less strenuous. after this it becomes much easier to concentrate because you're not putting much brain energy into unimportant things!

[@shawnshawn3751]

thanks sis

[@colehatmaker5009]

Maybe I’m missing something, but the description of theta, in the integral side of the equation in Ampere’s law, as the angle between the magnetic field and the current doesn’t seem to make sense. Isn’t it the angle between the magnetic field and any given point on the loop surrounding the wire?

[@robord7842]

I thought the same thing, but yes i think you are correct, where each point on the loop is described by what is called a loop element which is a vector that lies tangent to the loop at each infinitesimal point along it. It is described in this way since it is impossible to define the angle between a vector and a point.

[@shynanrahman9070]

HANK GREEN SHOULD TEACH ALL COURSES

[@maulikrushi5389]

Love from India

[@divvy1400yam600]

I also think it is wrong to express B (flux density) in the equation without the RHS including Mu0 I should be H (field strength) Also Ampere did not explain WHY magnetic fields can atttract or repel. He developed theories based on that OBSERVED fact.

[@samvidas9599]

I love her accent!

[@niranjansaikoppisetti1096]

actually the formula is incorrect. it is integral B.dl (dot product) is equal to µ x I. so integral dl around the loop becomes 2πr where "r" is the radius of the loop. then your derivation is true.

[@zeustheboerboel3794]

B.dl is just the vectorial form. In scalar, it is Bdlcostheta

[@Vaw.]

y'all should talk about king leopolds congo on the history vids

[@thesbeccompany7752]

which software used by u for edition video

[@bsuvraneel]

Hey! that torque on current loop part is completely wrong.... That loop must turn in backwards direction... Isn't it?¿?

[@markholm7050]

The animation of the magnetic fields around the parallel wires appears to me to be backwards, following a left hand rule instead of right. Am I confused, or is the animation wrong?

[@markholm7050]

It's the animation at 5:14 that seems to be backwards.

[@darknightofthesoul8980]

How about a video explaining how ecm electric motors work.