Zhou Jack That's true when I think about it again. I guess the scenario is complicated by the convention of using one acronym to refer to one particular thing rather than anything that can be appropriately acronymized. You are right, this surely needs some clarification; I was just trying to point out that people shouldn't mess around with acronyms and abbreviation too much, like "trans" is not always "transexual", it can also be "transportation" , "transformation" or "transition"; it would be wrong to associate acronyms and abbreviation to just some specific things, but I guess this linguistic demand is not really that relevant in this context. (This context in which electrons are not called "negatrons" :D)
Fiona, Question: The secondary magnetic field (green) is perpendicular to the wall of the pipe. It has no vertical component. If there is a force opposing the downward motion of the magnet, shouldn't there be a vertical component to the "opposing" field?
at 1:25 you say that a current is induced but the accompanying text says voltage is induced? From my understanding, the magnetic flux induces a variable current. The interaction between these two forces produces an emf which is actually a voltage that opposes current. Is this correct?
when we change the flux then electric field is induced wich exerts force on charges to move as induced current due to induce current megnatic field established which oppose the original megnatic field which is cause of it
So if you reversed the test, and had a magnetic rod without a cut though it, and you drop a non magnetic metal through the tube, would the non magnetic metal go faster or slower than the control test?
a question: what about iron vs moving magnet, explain the actions. there is eddy currents but differnt from copper, how exactly though, would thank you so much for this
I was also trying to do this experiment with a copper tube, but can not find a non-magnetic clamp like the one in your video.Where can I find one of these?
id like to see or know can u do this with copper wire and can u fold sheet metal to get thicker walls. ----- and and what point are u wasting copper in thickness
can this energy created by the eddy currents be harnessed or used? if so i have some really neat ideas where this could be used. looking forward to your reply, Thanks
May I ask, what would happen of this was a superconductor instead of copper? Do eddy currents work the same on superconductors? I would appreciate your answer.
Has anyone developed good *and correct* graphics showing the induced currents and magnetic fields in the sliding plate MIT demo shown later in the video?
Hi Gabriela, I think that´s simply because it locally changes. So as long as the magnet keeps falling down, locally, in every instant at every height you have a certain time-variant magnetic flux that induces the eddy currents that, in turn, induce local magnetic fields that do oppone themselves to the main flux (hence by point in the opposite direcction of it, and hence slowing the magnet down in its falls)...that´s just fascinating!
Brilliant video, I like the visualisation. I have a video here, Best Lenz's Law Demo - Floating Magnets Levitation from 1:20... Would love to hear your thoughts.
Is there a way to calculate the opposing force? How can I find a formulation that calculates the opposing force proportional to velocity? Or currently is it only possible throughout experimentation? Thanks!
Grizzledwarveteran23 yes by induction, you probably know the flashlights using that principle. They are recharging with a simple up and down mouvement. It's smart to ask the question because everybody knows the flashlights but I didn't see many answering your question but now you know.
Did you consider showing what happens to the braking effect with the opposite separation effect applied to the magnets using magnets "stacked" separated by impermeable spacers -> "stacked" disk magnets separated by impermeable spacers increase the breaking effect by causing each magnet field lines to induce separate eddy currents in the solid copper sled -> but what happens if you then also provide the slotted copper sled to that stacked magnetic field situation?
WARMING. Incorrect eddy current shown @ 1:38. It does not circle around the flux line. For the correct representation, pls refer to th-cam.com/video/yU_wwWC-K9c/w-d-xo.html.
I have three questions/comments. Although I didn't research this myself, our team in our nationals for the IYPT researched and presented upon this effect. We would be greatful if you answer for these questions. 1. Where does the mechanical force go to when the initial speed of the magnet is larger than the terminal velocity? 2. You mentioned that friction is not a factor, but the shape of the eddy currents in this case results in sticking being inevitable. Even if you drop at complete symmetry, it is impossible to not have contact with the wall. It is not easily calculable or an important factor, so it does not have importance, but your description of the matter was incorrect. 3. You are saying that a magnetic field induces a eddy current in the form of a circle upon the tube. But this is true of every point upon the tube. Then how does the eddy current retain its circular shape when two circles interconnect infinite times? Is it not more reasonable that the eddy currents are induced in parallel, and that induces a magnetic field which results in braking? This provides a force correlating with velocity implying that a terminal velocity exists. But from your qualitative apporach, I am not so certain.
Well, recently our team is also preparing for this problem... We have done a lot on mathematics and we finally prove that the retarding force is proportional to the vertical speed of magnetic. So if the initial speed is larger than the terminal velocity, the magnet will slow down to reach the "terminal velocity". Hope it can help you :)
the induced emf in the copper is stationary and repel the magnet and it take a force to vercome the repusion so the manget can create a new posistion for the induced stationary field. the induced field is stronger closer to the magnet inside the tube than further away. eddies is not the real problem. the stationary behavior of the induced repellig field is the problem. if the induced emf was moving with the magnet, the magnet would drop instantaneously through the tube.
@Fiona you lost me with the blue and red rings. If the red rings are eddy currents what are the blue rings? How do the red rings oppose the flow of the blue rings, it isn't clear in the animation. The explanation and video is really good up to the point of the red and blue rings, then its confusing after that. The live MIT demo at the end only proves the concepts, it does nothing to explain it. Would nice if you could add some captions into the animations to clearly indicate what the rings are and direction in which they flow.
the most irritating thing about electrical systems like these is that we are never told WHY the laws the way they are, like presuming the flow of electrons is actually how things work, why the heck would it create a magnetic field? and supposedly this magnetic field that acts as that of any magnet affects conductors by manipulating the magnetic domain of the the conductor making it a temporarily a magnet thus causing it to create its own magnetic field, but then where does the 'eddy' current in that induced magnet come from? do ALL magnets really have some internet eddy current going on in it? with supposedly zero resistance so the current is infinite?
You have to accept natural phenomena at some level. If we go on to say that electron spin causes magnetism, then you could ask why that is. We can, however, explain the most obvious characteristics, such as Fleming's Left & Right Hand Rules andd from them derive all the others such as Lenz' law.
You have to accept natural phenomena at some level. If we go on to say that electron spin causes magnetism, then you could ask why that is. We can, however, explain the most obvious characteristics, such as Fleming's Left & Right Hand Rules andd from them derive all the others such as Lenz' law.
Experiments back around 1860-90 using a Crookes Tube showed that it was the negative charge that was traveling. What you are asking for is a full course on all aspects of electricity and this is just one part of it. You won't get that in one 5 minute video. This video assumes some prior knowledge.
. I submit that these field lines and currents are not explained in the video and are incorrect. The statement: "Any change in the magnetic environment of the copper tube will cause a voltage to be induced in the copper tube" gives no indication of the *direction of* currents or field lines. The CHANGE: is opposed, not the field itself. The red line does not indicate how the field is *changing*. It is changing by sliding down. By Fleming's Right Hand Rule, this will cause a citcumferential current around the perimiter of the pipe, not the small circle shown... What gives..? The actual fields and forces are still not addressed by this video. Just Invoking Lenz's Law does not show how the fields are generated and their direction. Above the magnet, the green field should be in the SAME direction as the red field. Below the magnet, the green fireld should be opposite the red field. That is, there is an attractive force above the magnet and a repelling force below the magnet. These forces must have a vertical component if they are to slow the vertical fall. The lines shown here are all horizontal/radial, so they can not produce any vertical slowing of the magnet... Response please...!.? . ScienceAdvisorSteve
Late reply, but here's what I'm wondering. If the eddy currents were around the perimeter they would produce a magnetic field parallel to the direction of motion of the magnet which would result in no force on the magnet because of the qVxB relation, because sine of 0/180 is 0, right? So with that in mind, I think the eddy currents have to be as shown in the video.
@@lesa251 I just looked here... . You're somehow not thinking correctly. . Think of a regular solenoid coil. The current is in the wires all around the perimeter. The lines of the field are indeed parallel to the pipe length and along the direction of the falling magnet. A magnet in the center with the proper direction would be sucked in. Flipped around it would be pushed out. ,' When two magnets attract, or repel, end-to-end, the lines are parallel when two poles face each other. .... .. Do not miss the fact that there are eddies like the one shown like that *all around the perimeter* and they must sum. . The magnet's magnetic lines spread out all around the magnet from the pole, not just on one side or two sides as shown at 1:48. They form a cone with the "tip" at the pole and it opens and passes through the walls of the pipe ALL AROUND the circumference.. That image of just two lines is very misleading, apparently. There are an infinite number of those lines in that "cone". . Then, there are an infinite number of those little circles, all around the perimeter. The sum will be currents around the circumference. JUST LIKE THE COIL WITH CURRENT! . This is exactly how all the eddies sum up - to a current around the perimeter. It's been so long, but if not here, then other places this is explained; they all sumto a current around the perimeter. .. .. Above the magnet this current produces a field that attracts the falling magnet, "pulling upward".. .. Below the magnet, the field opposes the magnet and it repels, pushing up. .. This can be seen in a video on YT where the guy cools a VERY thick copper pipe in LO2. The field in the pipe starts to repel the magnet above the end of the pipe just before it enters... AND attracts it after is falls below the bottom for a bit. . Got it? .. .. .. It turns out that even if the magnet can tumble inside the pipe, it will still be slowed. It is like the pipe is a magnetic mirror and reflects the proper field to slow the magnet's fall. Pretty neat!
@@lesa251 Here. You can see the repelling below the magnet and the attraction above it in the pipe. . In this one around time 0:45 you can see it enter slowly and exit slowly. *th-cam.com/video/5BeFoz3Ypo4/w-d-xo.html* . HERE'S the liquid N2 cooled version, Mush better. !! Look around 0:20 and 0:48 *th-cam.com/video/AzOSYJmYLTg/w-d-xo.html*
EMF stands for electromotive force not "electromagnetic field". Correct me if I'm wrong
You are not, emf is used to refere to the induced voltage and is therefore not a field.
Zhou Jack The inferiority of acronyms are universal, no acronym is better than another.
In this context, I think there should be a distinction between the acronyms or else the information may be invalid
Zhou Jack That's true when I think about it again. I guess the scenario is complicated by the convention of using one acronym to refer to one particular thing rather than anything that can be appropriately acronymized. You are right, this surely needs some clarification; I was just trying to point out that people shouldn't mess around with acronyms and abbreviation too much, like "trans" is not always "transexual", it can also be "transportation" , "transformation" or "transition"; it would be wrong to associate acronyms and abbreviation to just some specific things, but I guess this linguistic demand is not really that relevant in this context. (This context in which electrons are not called "negatrons" :D)
I was about to comment that
Thank you Fiona! Excellent explanation, and very clear!!
Very cool. I worked on an eddy current in a scrap yard couple years ago.
Fiona,
Question: The secondary magnetic field (green) is perpendicular to the wall of the pipe. It has no vertical component. If there is a force opposing the downward motion of the magnet, shouldn't there be a vertical component to the "opposing" field?
Light also changed its velocity when entering from one medium to another medium
at 1:25 you say that a current is induced but the accompanying text says voltage is induced?
From my understanding, the magnetic flux induces a variable current. The interaction between these two forces produces an emf which is actually a voltage that opposes current. Is this correct?
when we change the flux then electric field is induced wich exerts force on charges to move as induced current due to induce current megnatic field established which oppose the original megnatic field which is cause of it
So if you reversed the test, and had a magnetic rod without a cut though it, and you drop a non magnetic metal through the tube, would the non magnetic metal go faster or slower than the control test?
If you were to force many many magnets through a copper tube, would the copper tube heat due to the current being produced?
Thank you Fiona. Great explanation.
I sure don't see the purpose of slow motion replays.
a question: what about iron vs moving magnet, explain the actions. there is eddy currents but differnt from copper, how exactly though, would thank you so much for this
I was also trying to do this experiment with a copper tube, but can not find a non-magnetic clamp like the one in your video.Where can I find one of these?
In the first example was there a current switched on?
Sir good morning, i would like to ask about near field tube testing if what is the formula of it's depth penetration.thank you sir
id like to see or know can u do this with copper wire
and can u fold sheet metal to get thicker walls. ----- and and what point are u wasting copper in thickness
Can you please explain why the magnet falls much slower through the slit area?
I think EMF means electro motive force 🤔
can this energy created by the eddy currents be harnessed or used? if so i have some really neat ideas where this could be used. looking forward to your reply, Thanks
do you know why there is a spark in the power switch after the power shut off?
May I ask, what would happen of this was a superconductor instead of copper? Do eddy currents work the same on superconductors? I would appreciate your answer.
Excellent explanation and examples
Has anyone developed good *and correct* graphics showing the induced currents and magnetic fields in the sliding plate MIT demo shown later in the video?
Why the magnetic field changes as the magnet falls? What area are we considering when analyzing de magnetic flux?
Hi Gabriela, I think that´s simply because it locally changes. So as long as the magnet keeps falling down, locally, in every instant at every height you have a certain time-variant magnetic flux that induces the eddy currents that, in turn, induce local magnetic fields that do oppone themselves to the main flux (hence by point in the opposite direcction of it, and hence slowing the magnet down in its falls)...that´s just fascinating!
Your voice is so soothing - I swear you should voice over documentaries or something.
You just earned a subscriber. Great video
thank you so much for this video. I finally was able to understand eddy currents. Other you tube videos confused me like anything.
Is Lenz's law used to create a flux capacitor?
'EMF' doesn't mean electric magnetic field . but overall presentation is auesome
Brilliant video, I like the visualisation. I have a video here, Best Lenz's Law Demo - Floating Magnets Levitation from 1:20... Would love to hear your thoughts.
whats the name of animation software? It's awesome
Is there a way to calculate the opposing force? How can I find a formulation that calculates the opposing force proportional to velocity? Or currently is it only possible throughout experimentation?
Thanks!
It will equal mg so it falls at a constant speed
If u put copper wiring around it can u harness electricity?plz help
Grizzledwarveteran23 yes by induction, you probably know the flashlights using that principle. They are recharging with a simple up and down mouvement. It's smart to ask the question because everybody knows the flashlights but I didn't see many answering your question but now you know.
@@patb686 And thats half the battle....
Did you consider showing what happens to the braking effect with the opposite separation effect applied to the magnets using magnets "stacked" separated by impermeable spacers -> "stacked" disk magnets separated by impermeable spacers increase the breaking effect by causing each magnet field lines to induce separate eddy currents in the solid copper sled -> but what happens if you then also provide the slotted copper sled to that stacked magnetic field situation?
Ok. Nice video, but what is a "chube"?
We had to do this for our Physics Evaluative task. My magnets kept rotating and getting stuck.
Very nice video, although I am pretty sure emf stands for electromotive force
WARMING. Incorrect eddy current shown @ 1:38. It does not circle around the flux line. For the correct representation, pls refer to th-cam.com/video/yU_wwWC-K9c/w-d-xo.html.
Very very nice video. Good explanation
Respect from India :)
I'm glad we could help!!!
Nice explanation
It's more important than people realize. They'll soon find out though.
Thank you so much, this was brilliant. :)
Thanks for the explanation, helped me a lot with understanding the topic.
I have three questions/comments. Although I didn't research this myself, our team in our nationals for the IYPT researched and presented upon this effect. We would be greatful if you answer for these questions.
1. Where does the mechanical force go to when the initial speed of the magnet is larger than the terminal velocity?
2. You mentioned that friction is not a factor, but the shape of the eddy currents in this case results in sticking being inevitable. Even if you drop at complete symmetry, it is impossible to not have contact with the wall. It is not easily calculable or an important factor, so it does not have importance, but your description of the matter was incorrect.
3. You are saying that a magnetic field induces a eddy current in the form of a circle upon the tube. But this is true of every point upon the tube. Then how does the eddy current retain its circular shape when two circles interconnect infinite times? Is it not more reasonable that the eddy currents are induced in parallel, and that induces a magnetic field which results in braking? This provides a force correlating with velocity implying that a terminal velocity exists. But from your qualitative apporach, I am not so certain.
Well, recently our team is also preparing for this problem... We have done a lot on mathematics and we finally prove that the retarding force is proportional to the vertical speed of magnetic. So if the initial speed is larger than the terminal velocity, the magnet will slow down to reach the "terminal velocity". Hope it can help you :)
+Gloria Jia Hello Gloria,
Could you calculate the force relative to speed? Is there a formula that you can share with us?
Thanks for the help :)
Can someone give me a mathematical comparison between conventional friction brakes and Eddy current brakes.....plz
_nice and excellent video_
the induced emf in the copper is stationary and repel the magnet and it take a force to vercome the repusion so the manget can create a new posistion for the induced stationary field. the induced field is stronger closer to the magnet inside the tube than further away. eddies is not the real problem. the stationary behavior of the induced repellig field is the problem. if the induced emf was moving with the magnet, the magnet would drop instantaneously through the tube.
Thank you so much what an excellent video!!
Very well done; you should do more like this.
Great video, very informative. Thank you for sharing / posting.
so good about working principle of tranformers
@Fiona you lost me with the blue and red rings. If the red rings are eddy currents what are the blue rings? How do the red rings oppose the flow of the blue rings, it isn't clear in the animation. The explanation and video is really good up to the point of the red and blue rings, then its confusing after that. The live MIT demo at the end only proves the concepts, it does nothing to explain it. Would nice if you could add some captions into the animations to clearly indicate what the rings are and direction in which they flow.
secondary magnetic field created by the eddy currents induced in the copper
the most irritating thing about electrical systems like these is that we are never told WHY the laws the way they are, like presuming the flow of electrons is actually how things work, why the heck would it create a magnetic field? and supposedly this magnetic field that acts as that of any magnet affects conductors by manipulating the magnetic domain of the the conductor making it a temporarily a magnet thus causing it to create its own magnetic field, but then where does the 'eddy' current in that induced magnet come from? do ALL magnets really have some internet eddy current going on in it? with supposedly zero resistance so the current is infinite?
You have to accept natural phenomena at some level. If we go on to say that electron spin causes magnetism, then you could ask why that is. We can, however, explain the most obvious characteristics, such as Fleming's Left & Right Hand Rules andd from them derive all the others such as Lenz' law.
You have to accept natural phenomena at some level. If we go on to say that electron spin causes magnetism, then you could ask why that is. We can, however, explain the most obvious characteristics, such as Fleming's Left & Right Hand Rules andd from them derive all the others such as Lenz' law.
Experiments back around 1860-90 using a Crookes Tube showed that it was the negative charge that was traveling. What you are asking for is a full course on all aspects of electricity and this is just one part of it. You won't get that in one 5 minute video. This video assumes some prior knowledge.
Vry nyc explanation...
Nyc video!! And gud demonstration!!!
Excellent video thank you !
Excellent video very easy to understand :) thanks so much
but y this law doesnt support with stainless steel metal?
it does
Most stainless steel is not a good conductor.
EMR radiation or resonance?
good demo
Excellent video... please make more. :o)
Very well explained
Respect from EGYPT
Nice explained
Thanks Fiona
its really amazing video
great explantion, thanks.
Its really very helpfull.. im in dilema upto nw but i got an idea abt this nw, nt bad 😇😇😃
. I submit that these field lines and currents are not explained in the video and are incorrect. The statement: "Any change in the magnetic environment of the copper tube will cause a voltage to be induced in the copper tube" gives no indication of the *direction of* currents or field lines.
The CHANGE: is opposed, not the field itself. The red line does not indicate how the field is *changing*.
It is changing by sliding down. By Fleming's Right Hand Rule, this will cause a citcumferential current around the perimiter of the pipe, not the small circle shown... What gives..?
The actual fields and forces are still not addressed by this video. Just Invoking Lenz's Law does not show how the fields are generated and their direction. Above the magnet, the green field should be in the SAME direction as the red field. Below the magnet, the green fireld should be opposite the red field. That is, there is an attractive force above the magnet and a repelling force below the magnet. These forces must have a vertical component if they are to slow the vertical fall. The lines shown here are all horizontal/radial, so they can not produce any vertical slowing of the magnet...
Response please...!.?
.
ScienceAdvisorSteve
Late reply, but here's what I'm wondering.
If the eddy currents were around the perimeter they would produce a magnetic field parallel to the direction of motion of the magnet which would result in no force on the magnet because of the qVxB relation, because sine of 0/180 is 0, right?
So with that in mind, I think the eddy currents have to be as shown in the video.
@@lesa251 I just looked here...
.
You're somehow not thinking correctly.
.
Think of a regular solenoid coil. The current is in the wires all around the perimeter. The lines of the field are indeed parallel to the pipe length and along the direction of the falling magnet.
A magnet in the center with the proper direction would be sucked in. Flipped around it would be pushed out.
,'
When two magnets attract, or repel, end-to-end, the lines are parallel when two poles face each other.
....
..
Do not miss the fact that there are eddies like the one shown like that *all around the perimeter* and they must sum.
.
The magnet's magnetic lines spread out all around the magnet from the pole, not just on one side or two sides as shown at 1:48. They form a cone with the "tip" at the pole and it opens and passes through the walls of the pipe ALL AROUND the circumference..
That image of just two lines is very misleading, apparently. There are an infinite number of those lines in that "cone".
.
Then, there are an infinite number of those little circles, all around the perimeter. The sum will be currents around the circumference. JUST LIKE THE COIL WITH CURRENT!
.
This is exactly how all the eddies sum up - to a current around the perimeter. It's been so long, but if not here, then other places this is explained; they all sumto a current around the perimeter.
..
..
Above the magnet this current produces a field that attracts the falling magnet, "pulling upward"..
..
Below the magnet, the field opposes the magnet and it repels, pushing up.
..
This can be seen in a video on YT where the guy cools a VERY thick copper pipe in LO2. The field in the pipe starts to repel the magnet above the end of the pipe just before it enters... AND attracts it after is falls below the bottom for a bit.
.
Got it?
.. .. ..
It turns out that even if the magnet can tumble inside the pipe, it will still be slowed. It is like the pipe is a magnetic mirror and reflects the proper field to slow the magnet's fall. Pretty neat!
@@lesa251 Here. You can see the repelling below the magnet and the attraction above it in the pipe.
. In this one around time 0:45 you can see it enter slowly and exit slowly.
*th-cam.com/video/5BeFoz3Ypo4/w-d-xo.html*
.
HERE'S the liquid N2 cooled version, Mush better.
!! Look around 0:20 and 0:48
*th-cam.com/video/AzOSYJmYLTg/w-d-xo.html*
EMF is electro-motive force NOT electromagnetic field.
Great video and even better accent! :)
u deserve more subs
thank you that helped a lot
Thank you.. I'm from Iraq and we study it in school
nice video
thank you
Best ever
Good
Scotty doesn't know, that Fiona and Me ....
When you learn about the center of a magnet, you will understand anti-gravity. It's real simple!!!
GOOD
👌👌👍
Woooooooooooooooooooooooooooo
another blalalala of electromagnetic tork!ups i need to learn some more not magnetic torc!!
my force formula F vector = 1 dl B = q/t dl*B = qV*B this is Lorentz law
i get it now! thanks
hahah that's cute, i'm from australia and we call it electromotive force
don't be so ignorant. In Australia and most likely the UK they call it electromagnetic force
Electromagnetic force.
EMF = Electro-Motive Force. Otherwise Lenz's law wouldn't make any sense!
lol
emf = electromotive force! -.-
Averagre
Chube.
very unseful, thank you
i cant hear a woman that explan some technical stuff...