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  • with a very thin piece of copper wire and a strong neodymium magnet and enough movement through the magnetic fields the copper should heat up enough to burn out 🔥

  • I'm not sure if you should be happy I like your videos so much or ashamed they keep me up so late 😂 thanks and never stop, these are amazing

  • Do you know how to make a Square Wave ? ? ?

    Me ? ? ?

    I have no idea . . .

    But I've heard . . .

    Once you get to know them . . .

    It is not a problem ? ? ?

  • FYI . . .

    Flux and Change . . . synonymous . . . the same word

    I tend to think of it as dropping a bowling ball from the top of World Trade Center . . .
    and having a sheet of glass at each floor to stop the ball if possible . . .
    (the glass represents the gap you create when you open the switch)
    if the first pane does not slow it down sufficiently it will continue to pick up speed on the way down . . .

    likewise the arc is picking up momentum in its state of flux (change)

  • I'm wondering… Is there a way, like with the water valve, to cut the current so fast that the energy in the coil and the magnetic field cannot escape? If so, what would happen?
    In my mind, I am theorizing that either the magnetic field would remain or the energy gets transformed into heat which then would be able to escape slowly by the known processes of cooling off.
    Would that be a usable guess?

  • Hey dear physics. First I love you in a father daughter type of way I would instantly adopt you if I could…. I know you already have a dear old dad he is a good guy must be because he has a super daughter!!! YOU are awesome and I don’t know about that person that has no joy but please keep this going it is awesome!!!!! I’m enjoying it with my grandchildren it is awesome awesome awesome you are awesome awesome awesome yeah creation is awesome awesome awesome physics is awesome awesome awesome so thanks 😃

  • the collapsing magnetic field induces current and voltage back into the circuit, you showed this with the shake weight. its also how a a/c transformer works, because the voltage oscillates it induces a magnetic field that then collapses 60 times a second ( in USA anyway) in Europe it would be 50 times a second

  • the simplest metaphor to explain to novice is: standing in a bus or train moving at steady speed. driver put the break on. you get thrown forward. you compensate by pulling Bach until you stabilize. those movement you experience is far greater than when moving normally. The Movement of electron in circuit create magnetic field. Switch stop current. the generated magnetic filed will claps. inducing current in opposite direction in the circuit. This make potential difference at brake point great enough to jump across the gap as spark until it stabilizes. MG1

  • When you look at all the haters in the comments, you will see that they have never made even a single video themselves. Easy to sit polishing a seat, with your feet kicked up and criticize others. *See Trump for the greatest example of all time.*

  • Sometimes I put the battery in wrong and then I am sad and I sit down and I watch Physics Girl and then I remember that batteries are mean to me, but I can still watch Physics Girl so I am happy 🙂

  • Not only does the magnetic field collapse, causing the current to flow, BUT the new current flow causes a magnetic field,… and it "rings" back and forth until the power is dissipated or the gap in the switch is too great for the ionized field at gap of the open switch (which is now a variable capacitor). Look at these (the switch/capacitor & the inductor) to see the diminishing ring. This can be tuned as well.

  • You’re absolutely amazing!! I hope my wonderful nieces enjoy your videos as much as I do!! Keep up the good work!

  • Physics girl I love your stuff you're brilliant, such energy (pun).

    but i can't help but think you would have been thrown in a river a 1000 years ago.

  • Sorry, but your summary is a little off. An inductor produces higher voltage than what was put into it, when the circuit is opened due to the energy stored in its magnetic field collapsing. The current produced by this effect flows in the opposite direction to the flow of current when the circuit is closed (when powered by DC). It’s a misnomer to think of it as the momentum of current, or relate it to water hammer. Also, circuits generally have flyback diodes to allow prevent the excess voltage from damaging components, so you shouldn’t get a spark when unplugging a well designed inductive circuit.

  • The water hammer model doesn't adequately explain why the voltage spikes so high. I know this phenomena can cause voltages that spike to thousands of times the voltage of the current that was originally flowing through the inductor.

    Since I first had the phenomena explained to me, I've thought about it this way… a moving magnetic field induces a current. A magnetic field that's collapsing is very rapidly shrinking. So it's inducing a current in the inductor that originally created it. I think the voltage of such an induced current is related to the speed at which the magnetic field is moving through it. Hence the high voltage.

  • I remember astudyimg this in college and found it so fascinating that I even kept the textbooks to refer back to later. magnetics and electromagnetics are very strange and interesting topics.

  • I think a better way of thinking of this is a moving magnetic field will push electrons in a condutor. Turn the switch off and the moving electrons that produce the magnetic field stops. Then this mag field collapses witch is moving inward …this collapsing field moves the electrons for a bit.

  • The way I imagined it is runners in a marathon. If you suddenly block a steady flow of runners, there will be a build up of the runners behind them (a la "objects in motion tend to stay in motion"). The build up will kinda cause some if the runners in the front to be "accidentally" pushed over the borderline.

    Love your channel, btw. Glad that your joy I still alive and well. 😁

  • There is actually a bunch of little greenies(alien creatures) in the wire and they are all driving down this road really fast trying to get to a party. When you raise the draw bridge on the road that they are driving on they start to pile up at the bridge as less and less of them can make it across … eventually there are so many greenies pilled up that they start to push so hard that the greenies can jump over the gap and get to the other side of the bridge. Eventually though they realise that the bridge is up and they cannot get to the party anymore, so they just hang on and wait for the drawbridge to come back down again. "There are no electrons" – book by ken amadahl

  • speaking of physics: I can honestly state that Dianna is often brings me to a melting point.. sooooo cute!

  • Here's a question that causes a lot of arguments among engineers>> what happens when you turn off that switch in a perfect vacuum?

  • Thanks! When I was 8, i took an iPod charger block and took of the thing that plugs in. I put two rusty nails in the holes. I put my finger on both nails and orange sparks went everywhere.

  • Don't ever stop being a curious child of science, it's infectious.
    The simplest way to explain inductance is with the collapsing magnetic field when power is turned off it's almost like moving a magnet through a coil, eg a generator.

  • Loved the water hammer analogy, you nailed it. Keep on, Keeping on Physics Girl, if you ever stop the universe would shutter.

  • cars still use induction to create a high voltage. That high voltage then goes to jump the gap at the spark plug and ignite the fuel air mixture in the cylinder

  • The spark in a modern car still uses inductors. The switch is electronic now-days and controlled by a computer the coil is not much different though.

  • Faraday's Mercury and Magnet Motor driven by the electric field is a good starting point for an extension of the idea to the cross-sectioning of the wire representing a particle in it's quantum-electric fields around the standing wave shape of the Magnetic field. The rotation of the motor is an extremely long-wave EM emission of wire's positioning while the conductor passes current.
    Stop the current and the electric momentum resists-reverses as the positioning of the field being pushed around collapsed. (Wave collapse in QM and all that stuff, too easy, if you know all information is this same Quantum Operator Fields Modulation Mechanism)

  • I love how interesting you're videos are and regarding the one guy's ignorant comment – don't let wet blankets like him ruin your fun! it's nice to see a video with someone just as excited as I am to learn about and see this stuff

  • You are super, girl! Just keep doing what you are doing just as you are doing it … teaching. Nothing is more important and you do it very well.

  • I saw these demos at MIT myself in the freshmen classes as of two years ago. The oxygen one I saw in 5.111 and the back EMF demo in 8.02, which I TA now. Maybe they added them in because of your input here!

  • Is solid state induction with magnets possible ? No moving parts . Possibly oscillating the induced current ?

  • Simply put the magnetic field collapses when you disconnect the circuit. The change in the magnetic field around the coil induces the current.
    Going more deep into the topic a magnetic field can collapse really fast which is why coils can create high voltage when you end the current flow suddenly like in car ignitions. Car ignitions are a little different because they have two coils, first coil is 12v and is the one who is disconnected, the second coil is inside the first coil and it receives the collapsing magnetic field and sends it to the spark plug.
    In the demo of this video you have basically a huge single coil. A point I want to bring up to not confuse is that the speed at which a magnetic field collapses is deeply related to the number of turns of the coil. Just like she said the bigger the coil is like the more momentum or something like that 🙃.

  • When turning "ON" the giant current-carrying inductor, You should get just the opposite of the giant spark, as "THE TENDENSITY OF CURRENT TO FLOW WORKS BOTH WAYS!" When turned ON, it does NOT want to start flowing so you should see no spark if you have a good sturdy switch and connect hard and fast, not much wear. That switch was a bit, not to sound insulting, flimsy. If the switch is nice and sturdy, the sparks still appear when it is opened properly, the sparks show up, and things get all corroded and yucky-burnt.
    a good example was at about timestamp 1:11 but the camera got switched about one frame too fast to NOT see the sparks when closing the switch!!!
    The water analogy is GREAT for both of these inertial effects.
    That is one great shrunken dime. Do you know the capacitor (C, V) ratings, and the wire size and # of turns used? I want to make some, I can't even see any radial stress lines, or signs of detail (writing) inward shifting. It really looks flat too!

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