Professor Carlson, compared to other instructors on this course, you really know how to make it so simple for your audience to comprehend this amazing disciple of physics. Thank you. *****
The charges do not move in the direction of the energy. There is an additional layer in the explanation, which requires either the understanding of Maxwell equations or the dynamics of the Poynting vector for a complete explanation...
I’m guessing some of these questions might be not easy to answer, as explaining basic electricity almost always seems to utilize some simplifications, while going into details seem end in Quantum physics (which is just bizarre and ultra counterintuitive). Have lots of questions, still most pressing at the moment are: 1. Why battery forces charges to organize themselves around conductor? What’s the mechanism? Why surface and not inside of conductor (guessing molecular structure disallows inside, but why allows outside)? 2. Why free electrons inside conductor heal to field created by charges - but not the other way around? After all both free electrons and charges are electrons. Why one rule over the other? Guessing obviously one are kept strongly by something while other free, still understanding lacks. 3 When battery is connected to conductor but circuit is still open conductor become “polarized”. Correct me. Some current flows for nano second in conductor? 4. Correct me. Polarized means there is more (or less - depending which pole) charges on surface of conductor which is however evenly distributed over length of conductor. Uneven distribution creates electric field and current flow? Thanks for making your lecture available.
Wow this is so good it helped me understand a lot of concepts which were not clear that i didn't under stand in school and checked online but this is by fat the best i have found
Professor could you clarify a doubt please. Following 2 popular theories seem to contradict each other: 1. 'Electrons around a loop, i.e. current around a loop, produces magnetic field like a bar magnet along the axis. But no radiation when it's a steady flow.' 2. 'An electron orbiting around an atom (in Rutherford model) should radiate energy, acc to classical electromagnetism'. Does an electron moving at uniform average velocity around a circular loop wire radiate?
an individual electron moving in a loop would radiate, since a distant observer would detect a changing EM field. however, a large number of evenly distributed electrons moving around a loop would not radiate, since a distant observer would not detect a changing EM field. maybe think of it as each electron's radiation being absorbed or suppressed by the other electrons
My new (electon) electricity says that electricity aint due to drifting electrons, or the Poynting Field/Vector, it is due to photons (electons) hugging the surface of the Cu. The electons propagate in the insulation (if any) in which case they propagate at the speed of light in the plastic, about 2c/3. On bare wires the speed of electricity is 3c/3. A good conductor is a substance that a photon can hug, eg all metals are goodish conductors i think. The hugging is strong if there are free-ish conduction electrons in the wire -- Cu has 2 such electrons per atom. Electons don’t reflect, they do a U-turn at the end of the wire. Actually, electons always go straight ahead, it is the surface of the Cu that duz the U-turn. If u measure the speed of electricity along a threaded rod u will find that the time taken is longer than for a plain rod, the difference being exactly the extra distance up & down over the threads. U should do a youtube about this. Your welcome.
Picture at 40:52 is wrong. I can put any surface charge anywhere on the surface, +ve -ve anything, but that doesn’t change the dc current one iota as long as the same battery and the same wires are used.
if the force for moving electrons comes from surface charge, what happens when the wire is 50 cm thick. Are you saying in this instance that the surface charge affects electrons inside and up to 25 cm away inside the wire? Also, you mention that electrons are accelerated. Doesnt this acceleration cause emission of photons?
I think it depends on frequency (which of course doesn’t exactly apply to DC), at higher frequencies no, the electrons inside don’t get affected. That’s why wave guides are used instead of wire in microwave ovens and for broadcast antennae, it cuts down on material costs without reducing the electromagnetic propagation. At least that’s my understanding at this point… DC is another animal tho.
…and I noticed you said force “for” moving electrons comes from surface charge - the force (voltage) is used “to” move electrons, which is the surface charge.. Current, not force is the measure of the moving electrons. Related is that electrons don’t move at the speed of electricity, but very slowly. If electrons were the transmission medium for electricity then when you flick on your light switch the light bulb would remain unlit as the electrons just “drift” back and forth over a short distance.
The battery terminal should charge/activate all the electrons in the wire close to it. How is it charging only the surface. ? Won't there resistance when the electrons cross the barrier, the bulb for example and thereby slow down the electrons at that point? How far an electron physically moves in a wire?
At 6:21... "... we don't really make a sharp distinction between gas and plasma..." Thus, I wonder, what's an example of gas, consisting of charged particles, that is not a plasma? The 'charged particles' part seems like a significant distinction.
Assuming by magnetic lines you mean lines of the magnetic field, lines are abstract not physical object. There are no any lines in the field - physically. Lines only represent direction force interacts with objects around the magnet. Hence there is nothing inside the magnetic lines. One way of seeing lines of field is placing magnet under paper, then sprinkling iron filings (iron dust) on top of paper. Filings going to organize themselves on paper along lines of magnetic field created by magnet underneath forming visible lines. m.ua-cam.com/video/snNG481SYJw/v-deo.html
Thanks for the wonderful explaination professor. For a given voltage, how thick can a conductor be ? For example, Can I take 9 Volt battery to light an LED bulb and use any thickness of the wire ? What if I use a wire which is 10 cm thick ? Will it glow ?
@@mjciavola Is there any limitation for the wire thickness.. what if i take wire of 1 meter in length and 10 meters in diameter(thickness) ? Will there be any change in the glow of the bulb ? (Intensity of current)
@@ksantosh7590 I'm guessing that as you approach infinity in wire thickness there might be some other effects showing up, but my understanding is that theoretically, wire thickness does not affect the current. Why do you think it would?
@@mjciavola I think due to more thickness of the wire, some part of the energy will be lost due to higher number of collisions (thicker the wire... more will be the collisions). Energy might be lost in the form of heat ? Not sure.
@@ksantosh7590 Ahh...Interesting. Since a thicker wire has more electrons being energized by the electric field, I would think that losses would not be a factor.
Professor, what do we actually mean when we say that a bit of charge "leaks" from each terminal? I'm reading Matter and Interactions and I'm a bit lost here as well. I understood the premise of feedback around bends in the circuit and how those bends create local electric fields. But she lost me when she extended it to saying surface charge is distributed all along both sides of the battery.
"Leaks" just means that some of the charge moves off of each terminal. It's an analogy with water. Can you please point me to the exact minute and second in the video when you felt "lost" about surface charge, and I will try to do better!
@@ProfessorCarlson I think it's a matter of me needing to see the electric field lines emanating from the battery and creating this near constant gradient of surface charge along the wire, from positive to negative. My guess is that the interactions between local electric fields and the battery's electric fields quickly become too complicated to show by hand? And you would need a computer to account for all the funky charge distributions that would happen--like the programs Dr. Chabay uses in her text? Ultimately, without getting into the gory details of how the fields from the battery and fields from local bends, surface charge tends to distribute itself into a nice gradient?
at 5:08 "as the electron goes around its atom it makes a current loop and a current loop makes a magnetic moment" Are you guys really still teaching that paradigm? especially coupled that with the remark 4:39 "okay the electron as far as we can tell has no size" how can you not smile? something that has no size is moving/spinning etc? You don't see the linguistic contradiction? Start by saying you have no idea and that following wrong models are used historically. Then the new generation will start dreaming up new paradigms that are closer to reality.
ua-cam.com/video/iMDTcMD6pOw/v-deo.html here Richard Feynman says honesty: he teaches what it LOOKS LIKE. He does not say this is how it WORKS. That would be like saying what it IS. Because 'LOOKS LIKE' is not 'IS' science can make progress in getting closer to it.
why you don't agree circuit electresite is like water hedrolic system 100% like ohms low and electron can mowe in any speed in circuit. not like speed close to speed of light
25:00 The electron(s) snails 1 m in 12h in DC it won't even reach the bulb during this class. In AC it moves back and forth an infinitely small distance. How are those electrons running??? and suppose to bump into things and create light they dont really even touch eachother... Immaginary water analogies make things even harder to understand in the end just like conventional current does. Why not try to teach the real stuff.. instead of crippling young minds??
Mosh pit analogy is why I'm cynical. Mosh pit doesn't cause peripheral movement always, but it can cause heat in closed space that I noticed on parameter but also some movement back though I understand what she's saying...It seems like these circuits should be closed, and then if they cause vibration or magnetism, peripheral activity can parasitically use it to power bulb..These chemistry people explain universe, but us selfish people have very base agenda. I would never be able to talk so enthusiastically about something if it had no opportunistic aspect to exploit, unless I was appointed by God or something. I have to try to listen closer.
Madam, your narration method is amazing, Hats off to your subject hold & mastery over the subject,
Professor Carlson, compared to other instructors on this course, you really know how to make it so simple for your audience to comprehend this amazing disciple of physics. Thank you. *****
Thanks for the kind feedback!
The charges do not move in the direction of the energy.
There is an additional layer in the explanation, which requires either the understanding of Maxwell equations or the dynamics of the Poynting vector for a complete explanation...
I’m guessing some of these questions might be not easy to answer, as explaining basic electricity almost always seems to utilize some simplifications, while going into details seem end in Quantum physics (which is just bizarre and ultra counterintuitive). Have lots of questions, still most pressing at the moment are: 1. Why battery forces charges to organize themselves around conductor? What’s the mechanism? Why surface and not inside of conductor (guessing molecular structure disallows inside, but why allows outside)? 2. Why free electrons inside conductor heal to field created by charges - but not the other way around? After all both free electrons and charges are electrons. Why one rule over the other? Guessing obviously one are kept strongly by something while other free, still understanding lacks. 3 When battery is connected to conductor but circuit is still open conductor become “polarized”. Correct me. Some current flows for nano second in conductor? 4. Correct me. Polarized means there is more (or less - depending which pole) charges on surface of conductor which is however evenly distributed over length of conductor. Uneven distribution creates electric field and current flow? Thanks for making your lecture available.
Wow this is so good it helped me understand a lot of concepts which were not clear that i didn't under stand in school and checked online but this is by fat the best i have found
Thank you 🙂
Great explanation of the Curie temperature !!! Thank you so much :))
Thanks mam helped me clear some concepts which they don't teach in highschool
Thank you. Very interesting video series...
Professor could you clarify a doubt please.
Following 2 popular theories seem to contradict each other:
1. 'Electrons around a loop, i.e. current around a loop, produces magnetic field like a bar magnet along the axis. But no radiation when it's a steady flow.'
2. 'An electron orbiting around an atom (in Rutherford model) should radiate energy, acc to classical electromagnetism'.
Does an electron moving at uniform average velocity around a circular loop wire radiate?
an individual electron moving in a loop would radiate, since a distant observer would detect a changing EM field. however, a large number of evenly distributed electrons moving around a loop would not radiate, since a distant observer would not detect a changing EM field. maybe think of it as each electron's radiation being absorbed or suppressed by the other electrons
@@Octa9on , excellent. Thx. I should have figured it out myself.
My new (electon) electricity says that electricity aint due to drifting electrons, or the Poynting Field/Vector, it is due to photons (electons) hugging the surface of the Cu.
The electons propagate in the insulation (if any) in which case they propagate at the speed of light in the plastic, about 2c/3.
On bare wires the speed of electricity is 3c/3.
A good conductor is a substance that a photon can hug, eg all metals are goodish conductors i think.
The hugging is strong if there are free-ish conduction electrons in the wire -- Cu has 2 such electrons per atom.
Electons don’t reflect, they do a U-turn at the end of the wire.
Actually, electons always go straight ahead, it is the surface of the Cu that duz the U-turn.
If u measure the speed of electricity along a threaded rod u will find that the time taken is longer than for a plain rod, the difference being exactly the extra distance up & down over the threads.
U should do a youtube about this.
Your welcome.
Electron, not electon
Picture at 40:52 is wrong. I can put any surface charge anywhere on the surface, +ve -ve anything, but that doesn’t change the dc current one iota as long as the same battery and the same wires are used.
if the force for moving electrons comes from surface charge, what happens when the wire is 50 cm thick. Are you saying in this instance that the surface charge affects electrons inside and up to 25 cm away inside the wire?
Also, you mention that electrons are accelerated. Doesnt this acceleration cause emission of photons?
I think it depends on frequency (which of course doesn’t exactly apply to DC), at higher frequencies no, the electrons inside don’t get affected. That’s why wave guides are used instead of wire in microwave ovens and for broadcast antennae, it cuts down on material costs without reducing the electromagnetic propagation. At least that’s my understanding at this point… DC is another animal tho.
…and I noticed you said force “for” moving electrons comes from surface charge - the force (voltage) is used “to” move electrons, which is the surface charge.. Current, not force is the measure of the moving electrons. Related is that electrons don’t move at the speed of electricity, but very slowly. If electrons were the transmission medium for electricity then when you flick on your light switch the light bulb would remain unlit as the electrons just “drift” back and forth over a short distance.
The battery terminal should charge/activate all the electrons in the wire close to it. How is it charging only the surface. ?
Won't there resistance when the electrons cross the barrier, the bulb for example and thereby slow down the electrons at that point?
How far an electron physically moves in a wire?
Congratulations, fantastic lecture!
Thank you!
Why does the hand chirality matter if you don't specify the polarity of the magnetic field so produced?
At 6:21... "... we don't really make a sharp distinction between gas and plasma..." Thus, I wonder, what's an example of gas, consisting of charged particles, that is not a plasma? The 'charged particles' part seems like a significant distinction.
Do the electrons move slower after leaving the bulb (like a water wheel slows down the water)?
no
I always wonder what is inside the magnetic lines that surround a permanent magnet ? nobody can tell me...
Assuming by magnetic lines you mean lines of the magnetic field, lines are abstract not physical object. There are no any lines in the field - physically. Lines only represent direction force interacts with objects around the magnet. Hence there is nothing inside the magnetic lines. One way of seeing lines of field is placing magnet under paper, then sprinkling iron filings (iron dust) on top of paper. Filings going to organize themselves on paper along lines of magnetic field created by magnet underneath forming visible lines. m.ua-cam.com/video/snNG481SYJw/v-deo.html
_Magnetic Flux._ But to find out what that is you need a _flux capacitor_ AND you need to be in _relative motion at 88mph..._
Thanks for the wonderful explaination professor.
For a given voltage, how thick can a conductor be ? For example, Can I take 9 Volt battery to light an LED bulb and use any thickness of the wire ? What if I use a wire which is 10 cm thick ? Will it glow ?
Sure, why not? The thicker the wire, the less resistance, making the conductor even better!
@@mjciavola Is there any limitation for the wire thickness.. what if i take wire of 1 meter in length and 10 meters in diameter(thickness) ?
Will there be any change in the glow of the bulb ? (Intensity of current)
@@ksantosh7590 I'm guessing that as you approach infinity in wire thickness there might be some other effects showing up, but my understanding is that theoretically, wire thickness does not affect the current. Why do you think it would?
@@mjciavola I think due to more thickness of the wire, some part of the energy will be lost due to higher number of collisions (thicker the wire... more will be the collisions). Energy might be lost in the form of heat ? Not sure.
@@ksantosh7590 Ahh...Interesting. Since a thicker wire has more electrons being energized by the electric field, I would think that losses would not be a factor.
Professor, what do we actually mean when we say that a bit of charge "leaks" from each terminal? I'm reading Matter and Interactions and I'm a bit lost here as well. I understood the premise of feedback around bends in the circuit and how those bends create local electric fields. But she lost me when she extended it to saying surface charge is distributed all along both sides of the battery.
"Leaks" just means that some of the charge moves off of each terminal. It's an analogy with water. Can you please point me to the exact minute and second in the video when you felt "lost" about surface charge, and I will try to do better!
@@ProfessorCarlson I think it's a matter of me needing to see the electric field lines emanating from the battery and creating this near constant gradient of surface charge along the wire, from positive to negative.
My guess is that the interactions between local electric fields and the battery's electric fields quickly become too complicated to show by hand? And you would need a computer to account for all the funky charge distributions that would happen--like the programs Dr. Chabay uses in her text?
Ultimately, without getting into the gory details of how the fields from the battery and fields from local bends, surface charge tends to distribute itself into a nice gradient?
Thank you very much.
loved it
Thank you! 😄
How it works that battery chemical energy turned to light heat,electrons is pushed by surface electric field,then what battery do?thank you.
I LOVE IT , THANK YOU .
So glad to hear it's helpful!
prof.Carlson, Which book do you use for this course?
We use Matter and Interactions, Volume 2: Electric and Magnetic Interactions by Chabay and Sherwood.
at 5:08 "as the electron goes around its atom it makes a current loop and a current loop makes a magnetic moment" Are you guys really still teaching that paradigm? especially coupled that with the remark 4:39 "okay the electron as far as we can tell has no size" how can you not smile? something that has no size is moving/spinning etc? You don't see the linguistic contradiction? Start by saying you have no idea and that following wrong models are used historically. Then the new generation will start dreaming up new paradigms that are closer to reality.
ua-cam.com/video/iMDTcMD6pOw/v-deo.html here Richard Feynman says honesty: he teaches what it LOOKS LIKE. He does not say this is how it WORKS. That would be like saying what it IS. Because 'LOOKS LIKE' is not 'IS' science can make progress in getting closer to it.
Wow I like that
Anyone know what year student is in this class?
This course is aimed at freshmen and sophomores in science and engineering majors.
cool
Thanks!!
why you don't agree circuit electresite is like water hedrolic system 100% like ohms low and electron can mowe in any speed in circuit. not like speed close to speed of light
25:00 The electron(s) snails 1 m in 12h in DC it won't even reach the bulb during this class. In AC it moves back and forth an infinitely small distance. How are those electrons running??? and suppose to bump into things and create light they dont really even touch eachother... Immaginary water analogies make things even harder to understand in the end just like conventional current does. Why not try to teach the real stuff.. instead of crippling young minds??
I egreed with you .I think electron flew in circuit like water in piep and I egreed whit ohm low.
It's explained in the next lecture..
if you see this comments please 🙏 answer my questions it's very important for me to know your opinion.
She's a live wire!
Mosh pit analogy is why I'm cynical. Mosh pit doesn't cause peripheral movement always, but it can cause heat in closed space that I noticed on parameter but also some movement back though I understand what she's saying...It seems like these circuits should be closed, and then if they cause vibration or magnetism, peripheral activity can parasitically use it to power bulb..These chemistry people explain universe, but us selfish people have very base agenda. I would never be able to talk so enthusiastically about something if it had no opportunistic aspect to exploit, unless I was appointed by God or something. I have to try to listen closer.
its called ELECTRIC FIELD
include real life examples like making austenitic steel from ferritic.
They need to quit moving away from the formulas. I don't have time to read them.