Lenz's Law | Magnetic forces, magnetic fields, and Faraday's law | Physics | Khan Academy
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- Опубліковано 15 жов 2024
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Lenz's Law - seeing that the magnetic field induced by a current induced by a change in magnetic flux (Faraday's Law) counteracts the change in flux.
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I am very impressed by the right hands that you drew.
me too lol :)
Same lol
Greg Overbeek me too lol
Yup he is a star
It was awsome but the first one looked somewhat like a pigeon with a backpack.still awsome 👍
"Let me find a nice color for the current". Love you Sal.
Perfect voice, perfect drawings, perfect colours, PERFECT EXPLANATION
+Perrin Tan He's been perfecting this art since 2006.
love the captitals at the end lol
his voice annoying afs
Sal gotta start narrating documentaries now that David Attenborough has retired.
@@adansilva6851 I know, he went from a 4 to an 11 in eight words
4 teachers/lecturers explained this to me and I didn't get it. This video makes me finally understand the law. Why am I even paying for uni
Legit, uni made me hate physics :(
Excuse me, is this uni material only? I say it because I feel bad for not remember learning any of this in school.
Dord Abacot No, it's school material as well. It's just I didn't do physics in school, but decided to do it in university. Initially, they teach you basic physics (not extremely basic...), but then get onto the real thing. So this is the basics we were learning.
a current through a wire creates a magnetic field in the direction of the RHR
From Faraday's law, changing magnetic flux will induce a current.
So if you increase the magnetic field, you increase flux and create a current.
The direction of that current has to create a magnetic field that goes in the oppostite direction as the change otherwise it will increase infinitely
What I am learning this in Grade 10 in my country😖
when you come to Khan academy wanting to learn physics and get an art lesson in the process
You are a F.....G Legend, What my teacher couldn't teach me in 2 months, you taught me in 6 minutes.
Keep up the awesome work.
Just saw this, and in my mind it's the graphics plus the excellent explanation that drives this home.
pays $$$ for college. comes to youtube to learn for free.
Several ivy league universities make courses available for free, but doing so gives you no diploma, nor does UA-cam. Employers will demand that as proof.
$25k a year along with a $200 textbook that just leaves me confused and having to come to youtube to learn even the most simple concepts. whatever gets me a degree i guess.
Pays 0$ to learn physics as a general education requirement at a public high school... Comes to youtube because he's drunk on a Friday and doesn't pay attention in class.
U r learning this in university?
Unfortunately no "University of Khan" degree at the end of it.
This was such an amazing video! First time here, but I understood with an unexpected ease since Physics is my Achilles’ Heel. Thank you so much sir 😊🇮🇳
I've been stuck trying to understand this law for a couple days now. I didn't know that a 6 minute video could make me finally understand it. Thank you!!!
(Also the hand drawings are pretty good!)
thank you!!!
-UCLA student with physics final in two days and still doesn't understand lenz's law
How did you get into UCLA then?
@@Yashraj100x do you go to first grade to learn to add or do you go already having learned how to add only for them to teach you again?
@@tfw_e8370 she said can't understand not can't remember
@@Yashraj100x people come to these videos to learn/increase their understanding of topics, so what are you getting at
Cool, please keep on making physics videos' sir! After you finish electromagnetism, could you please start to explain quantum mechanics? Please?
How could he have so deep understanding of almost all disciplines? Huge respect and love.
I think I want to add that for some reason "the conservation of energy" (which is mentioned at 5:00) isn't said by teachers when teaching this concept. It took multiple youtube videos before I finally heard that phrase, and I figured it was the case, but still. It helps to know *why* Lenz's law is working. I'm sure the textbook says it, but those things are written by out-of-touch people.
Infinity loop of increasing energy 😂😂dude nice explanation . Thanks a lot sal . It does a lot for students like us
I wish the law of conservation of energy could be violated somehow
Can you just make a Khan University? You guys explain this stuff so much better than my textbooks and professors...
You study these in universities? I'm not in university yet, I've to study these so that i can enter a university 😅
At 4:27 when he draws the arrow of the magnetic field due to the current (purple one) . Why wouldn't it be drawn upwards since using the right hand grip would show your fingers curling upwards?
Years of studying and no one could give me the explanation youve given. Thank you very much
This is a very clear lesson. I just loved it. Thankyouuuuuuuu
These videos will be clutch later this year during my first year of college.
Thank you so much! With online classes, some professors have posted mediocre slides which were OBVIOUSLY meant to create class discussion, but since there's no class, there's just incomplete lessons.
You explained this WAY clearer in 5 minutes than my phsycis 2 professor did in an hour.
The hand looks real artistic ^^
I've been coming back to this video so many times! No one has explained Lenz's law better. Thank you so much!
The energy in his voice is never ending... He's violating the law of conservation of energy!!
ugh sorry im having to ask this: but how does the right-hand rule for counterclockwise and clockwise on the left-side coil on clockwise picture (4:24) point at the same direction (therefore same hand gesture) but counterclockwise produce an additive force but subtractive force for the clockwise one?
Awesome video! but I have a small question: I did not understand that you said energy is created if the magnetic field created by the current is in the same direction of the magnetic flux, which violates the law of conservation of energy. What energy is being created?
He was saying that would be the case if the current was moving counterclockwise, which would be the incorrect answer. If it were moving counterclockwise, the field generated by the new current would agree with the change in magnetic flux, boosting it and that would incorrectly be energy from nowhere. However, in reality the current will move clockwise, generating a field to resist the change in flux, and that resistance to change is what forces the current to happen in the wire.
I go to school every day to waste 2 hours listening to my professor whose so bad at explaining then go home watcha 6 min video that explains in a very simple and fun way bliss, you man
I just love this guy. How is it possible that I understand this but not the book?
Khan academy you always give me something much better than my expectations THANK YOU 😌 ☺ KEEP GOING 👍👍
My professor doesn't post lectures for my physics 2 class, he just assigns two chapters a week and doesn't answer emails. Khan Academy is literally teaching me more than I learn in college.
It's taking me a yearrr to understand this concept...
Idk how I will do on my physics exam tomorrow 😥
And this actually helps me understand the basic concepts
Thank you :)🙏
love how you explain the right hand rule and draw everything perfectly #khanuniversity #howigotthroughcollege
Seriously, simple presentation and on point explanation made it very intuitive. Thanks a lot !
How energy is conserved??
Sal Khan is simply a beautiful teacher. Thankyou
Sir i started my physics high school with your videos but couldn't end my high school with them as they were not sufficient . like i learnt newton's laws but could not learn semi conductors from your videos. Sir i hope that you concentrate more on the physics videos as physics has to be more conceptually understood. i beg you sir please
I have a question for you Sal!
Which HW/SW do you use to be capable to draw smoothly!
I tried the mouse but it is not handy!
+abdallah13th Not sure what program he is using (he originally used MS Paint and later SmoothDraw I think), but I heard he uses a Wacom Bamboo tablet. I personally use a UGEE tablet, which is a lot cheaper but of course not as good as the Wacom.
+abdallah13th This software he is using is a bamboo brush and pen. It is pretty cool, look it up on Amazon and I am not sure what it will do.
Bruh i was searching for this exact explanation for 3 years now. I always took lenz law for granted but i now know the physical reason behind it. I sleep in peace now
Actually the Right hand rule was spot on., Thumb in direction of current flow curled fingers show magnetic field imposed cw or ccw. Lechatelier's Law= For every action there is an equal and opposite reaction.
Questions about this video: When you draw the hand and the fingers wrapping around, the fingers are pointing back toward the thumb. The additions to the flux are in the direction of the palm of the hand. Could you explain this better?
Thanks!
+KidsandKarma imagine yourself opening a bottle of water when u go in a certain direction the tip goes up.. saaame thing.. it's what I use, way easier. If ure still interested..
Thanks, but what do you mean by "The tip goes up"?
It's called the "right hand grip rule" (if you google it you'll probably get clearer diagrams), the fingers are supposed to be wrapping around, and making a loop (think of it it like a ring circling the wire). These loops represent the magnetic field lines/lines of flux.
If you look in the video, on the diagram on the bottom right, with those orange lines he drew. These orange lines were representing a part of these lines of flux. If he continued them on, they'd curve round to the right and make a loop, joining onto the bottom end of themselves.
Apart from being a great teacher, he is also a good sketcher. Nice little right hand illustrated Sal! XoxO
thank you VERY much. khanacademy is always so helpful after everyone fails
I have a quiz in the morning and my mind was about to explode i was stuck at the lenz's law, this video got me literally goosebumps the way he taught it. I never knew it was that easy. Thank You sooo muchhh for this effort!!!
Learnt this at Sixth Form College and twice at university with different schools (mathematics and engineering).
Despite that, this is the best and simplest explanation I have seen.
I'm confused. In what direction is the current in the video going? The scientifically accurate negative to positive or the industry standard positive to negative?
I can't get over how perfect your right hand drawings are!
Thank you, now I actually understand Lenz's law and not just some words from a book.
2:14 the art was good
i am confident that this is the best teacher voice i ve ever heard
but the flux lines generated by the wire is curled so how do they oppose or contribute to the flux lines pointing up ?
2:20
very easy to understand.
How do you determine the direction of the current? "The direction of an electric current is by convention the direction in which a positive charge would move. Thus, the current in the external circuit is directed away from the positive terminal and toward the negative terminal of the battery. Electrons would actually move through the wires in the opposite direction."
draw the hand. Jaw dropping...
If the changing flux surrounded the entire conductor loop so that it was on the outside perimeter of the conductor as well as the inside, would the induced current then be zero due to the flux effects' on the conductors cancelling each other out?
I never comment on UA-cam videos, but this was insanely helpful. Thank you Sal!
An amazing explanation.. thank you a lot to make me understand that law, I'm so grateful!
Thanks for this, one of the best explanations ever!
Hello sir
I have a question please, which is :
Let us have a circle to put it on a horizontal paper,
if there is an induced current passes counterclockwise through the circle, while the magnetic field is going upward (out of the )paper). So, what would be the reason :(the increasing of the magnetic field passed) , or ( decreasing of the magnetic field
Please, can you explain that on you tube ?
I appreciate .
just draw a circle on the paper, and put the direction of the current. then do the right hand rule. you can see that your fingers will show that the magnetic field goes out of the paper. in order for this you should decrease the magnetic field passed to oppose it, because the magnetic field is going outward also and according to lenz law you gotta decrease it.
The best possible explanation!
Thank you sir!!! You have increased my confidence in Physics. People always try to demotivate me but you have motivated me to persue my favourite subject.
Thank you finally i found an excellent explanation
So it only OPPOSES the change in flux if it is INCREASING therefore the induced magnetic flux would go the opposite direction, otherwise (if the induced magnetic flux is decreasing) it adds to it = does not oppose it??? Is this correct?
it still oppose it, if the magnetic flux is decreasing(going down), then the induction current would go up in order to stop its decreasing.
I am confused by different concepts on Internet and your argument .
I am not clear
They say Induced current is in counterclockwise in circular loop when north pole approaches
nice drawing of thumbs
what would be the direction before increasing flux????
Very Beautiful explanations!
you're best than my teacher....thanks you
When looking at this more carefully I realized 2 things. First, the right hand rule will only work if one is NOT standing in the center of the hoop, and if one does NOT reach across the hoop to grab the other side of the hoop. secondly, and more interestingly, the magnetic flux lines travel in one direction, where as the electric flux lines travel in 2 directions, like a spiral. So the electrically charged particles travel around the wire, but also down the wire. Whereas the magnetic flux lines only travel around in a circle. Is this correct? Does this have to do with the fact that magnetic flux lines are always bipolar, whereas electric charges, like electrons, are always mono polar? Are electric flux lines, and magnetic flux lines in fact 2 different phenomena? We are usually taught that these are 1 phenomena that we call electromagnetic, but I'm seeing 2 very odd phenomena, especially regarding electric charges traveling in a spiral down, and around a conductive wire. This in turn makes me wonder how a flux line leaving the north pole of a magnet can circle around and enter the south pole and then exit the north pole again. With the reverse happening at the south pole. What is going on here? Are the magnetic flux lines leaving a magnet traveling in a spiral through space as they exit the bipolar magnet, like the electric flux lines traveling down a wire via electrons? This is getting into quantum physics because we would want to know what exactly are flux lines. I've heard that they are in fact photons, and that flux lines don't really exist. A Khan video, or 2 explaining this would be very helpful. Perhaps there are and I just haven't found them out yet. Thank you:)
I think your first assertion is incorrect. Try it again... the right hand rule will give the same results whether you are standing inside or outside the conductor loop, or if you reach across. Remember, you have to wrap your fingers all the way around the conductor and also current on one side of the loop is moving in the opposite direction as the other side of the loop.
As for your second statement I kinda have no idea what you're talking about, but from what I understand the lines of flux (whether electric or magnetic) are not particles and they don't "travel", they just represent the direction and magnitude of force that an electron (in an electric field) or magnet (in a magnetic field) would feel at any given location.
As I understand, if the loop of wire moves in the same direction as the vectors from the sationary magnetic field, it means the wire never cuts any magnetic line, thus no current should be generated. Could you pleas explain what am I missunderstanding? Shouldn't the magnetic lines be horizontal rather than vertical?
THANK YOU SO MUCH SIR!! The most clear explanation I have ever seen!😆😆😆
I really appreciate your videos. Nevertheless there is a small flaw in reasoning in this one. Even if a generated current would increase magnetic flux it is not said that it would cause infinite gain. That is because a _change_ of flux is what inducing a current not a strength (density) of it. So you could have very strong externally generated flux with just a little change over time. This way flux induced by a current would be negligible. Another thing. In the moment when you will cease to increase external flux the current will drop. When a current drops induced flux also drops. Drop in a flux means generation of a current in a reverse direction.
superb explanations. If you could simplify the LENZ'S LAW (the statement) and provide that to us, would be helpful.
This video is a piece of art, this is legit explanation, don't know how to thank you.
thanks sir , I will never forget that you have said " this is the violation of law of conservation of energy " and from this statement I have understood the lanz,s law very successfully.
For automotive, just know that using a clamping diode will help dissipate the large voltage spikes after the circuit is opened [In coils and electric motors].
According to the right hand rule, the inner part of the hoop will indeed try to reduce the change in flux , but what about the outer part of the hoop?
Perfect explanation and thank you so much 🔥🔥🔥🔥🔥🔥🔥🔥
This is one fo my favorite laws. Its a fun law to learn about. I always think about lenz’s law being best friends with conservation of energy law because it defend it. Lol
That's The Best Explanation PLEASE KEEP IT UP THANKS FROM MY BOTTOM OF HEART
Why is an increase in flux represented by taller lines? Surely the length of the lines is irrelevant, it is the number of lines (the density of lines) which represents an increase in field strength and therefore flux as more field lines (flux) are passing through the coil/area?
Awesome your redoing the Physics playlist. The most important science ever even more important than math because its ground in reality and not abstraction.
2:53 That energy !! Love it :))
This is by so far the best lenz's law explained. Thank you sooooo much!
how do you know the direction of the change in flux
Wait so if the current in the first example increased the flux which then increases the current in a never ending cycle. Then why in the second example doesn’t the flux decrease lead to a decrease in current. Creating another cycle
amazing video i got it in seconds. Great !!!!! this is what u call an EXPLANATION
How are u so damn good at every single thing u teach?????????????? bio phy maths or mayb even music... its just awsome
Look at that right hand, and add art to your list :P
Economics and English too!
Amazinggg lecture
Best explanation of lenz law ever before I was so confused
Can someone explain 4:10 to me. When it's going in the clockwise on the other side how is it still pointing downwards?
I guess the magnetic flux is pointing out of the loop if you understand what im saying
Meaning that when u coil your fingers up the magnetic field lines are out of the loop of wire which he had drawn, thus it does not increase the total magnetic flux in the range of the loop of wire. Hope this helps
Thanks a lot. Really helped me understand Leno’s law better than my grade 12 physics textbook.
Think this is the second one i have seen on Laws, kind of into that. Thank you for the free content.
I truly understood the Lenz law today..thnk u sir.. Impressive explanation
Why does electromagnetism follow the right hand rule? Or say left hand rule for conventional or electron current whichever what decides the either direction?
is this on your website?
+Junran Cao www.khanacademy.org/science/physics/magnetic-flux-and-faradays-law/magnetic-flux-faradays-law/v/lenzs-law
+Grant Wilkins Thank you very much.
Can’t thank you enough!
Went here to compliment the right hand drawing skills... you guys beat me to it
simply Perfect....Thank You so much
Great sir