This was great, thank you. The animation is what really drove the concepts home for me. I wasn't able to tell if the external field actually crossed into the conductor; none of the textbooks clarify it well. Thanks again.
1. Electrons concentrate at surface points & dilute at flats. This is ignored in the drawing. 2. What we call fields are actually inventions. They are made of lots of small (mini) true fields. 3. Each true field is emitted by each electron & each quark etc, in the conductor, & in the universe. 4. Each true field propagates in a straight line. 5. Each true field has a beginning but no end (fields go to infinity for ever). 6. In which case every conductor is full of true fields. 7. Nett fields are an invention. 8. Nett fields are zero inside the (metal) conductor (because some conduction (free) electrons move). 9. But the conductor is always full of (mini) true fields. 10. I see one comment that says that nett field lines should enter (or leave) the conductor perpendicularly. I think i agree.
You are absolutely right about fields being an invention, and also about the way that charges collect at the points! The reason I made this video (a LONG time ago!) was to help my students visualize the processes that lead to two basic outcomes: (1) the field strength inside a conductor in equilibrium is zero, no matter what the external field is and (2) that all the net charge resides at the surface. I was absolutely intentional about dodging the details, details that you are correctly point to. cheers!
I want to ask about the picture where you show us that one part is more negative and other part is more positively charged (cause the electron move from there). When you use that picture and use a Gaussian Surface, it is easy to tell that the net charge inside the surface is zero. Cause it is perfectly constructed that the positive and negative charges are reside one the edges. But is it true that the positive charges on the edges? what about the charges like in the center? I don't quite understand the transformation of the pictures...
Forget about this video. Listen to me. Lets say you have metal sphere and you place that metal sphere in an electric-field (as, for instance, bringing it closer to another charged body. This is called induction). When you place the charge-neutral metal sphere in the electric-field and your electric field is produced by a positive charge. What happnes is that the negative charges on your sphere try to be as colose to the positive-charge (external, whose electric field we are talking about) as possible and positive charges on the sphere will try be as far as possible from where the elctric field of the proton is coming. And so in this way, may be, half of your sphere has positve charge and half of your sphere (towards the positive-electricfield) has a negative charge. It is very simple, there is nothing mysterious about it. ( You would probably not see my comment but hopefully, it will help someone else!
hey man in my book it is stated that the electric field lines are perpendicular to the surface of the conductor because if it wasn't, there would be some tangential component of the field along the surface. Now the explaination given is that because of the component there will be force and the charges will move and as this cannot happen, there can be no tangential component. Whereas the explanation should have been that the charges inside readjust to counter the tangential component and hence only the perpendicular field lines would remain. right? btw thanks.
I made the video ten years ago. You wrote this comment two years ago. Yet here I am on a dark January afternoon going "awwwww, what a sweet thing to say!" Thank you!
I want to ask about the picture where you show us that one part is more negative and other part is more positively charged (cause the electron move from there). When you use that picture and use a Gaussian Surface, it is easy to tell that the net charge inside the surface is zero. Cause it is perfectly constructed that the positive and negative charges are reside one the edges. But is it true that the positive charges on the edges? what about the charges like in the center? I don't quite understand the transformation of the pictures...
I think you are asking about the change in the pictures at 3:25 where I go from showing big fat +s and -s all over, and just show little + and - at the edge. Am I right? How come all the + and - have to be at the edges, and does that work for positives as well as negatives? Here is how the argument works: Suppose there IS some unpaired positive charge inside the body of the conductor. If that's true, then we know there must also be nonzero Efield inside the conductor. We know this because we can draw a Gaussian around the + charge; Q≠0 tells us ø≠0 so there must be some nonzero field inside the conductor, and that field will point away from the positive charge. But remember, this is a *conductor* -- the charges can move. If we are talking about something ordinary like a hunk of metal, then there are free electrons that will travel "upstream" in the field -- toward the positives. As long as there is field there will be charge flow, and the charge movement will continue until there is no field. When is there no field? When the unbalanced charge is neutralized. The only way this charge-balancing routine can be interrupted is if the field is in a NONconducting realm, and the only way this happens is when part of the Gaussian must be drawn in nonconducting turf. The only charges that require such a Gaussian are on the surface of the object. So the only place where charge can reside in equilibrium is the outer surface. I hope that helps! ds
This was great, thank you. The animation is what really drove the concepts home for me. I wasn't able to tell if the external field actually crossed into the conductor; none of the textbooks clarify it well. Thanks again.
I love your explanation. Great video!
Appreciate your work sir it's really help me.thank you 🙏💕
Very nice explanation sir.. Thank u so much
1. Electrons concentrate at surface points & dilute at flats. This is ignored in the drawing.
2. What we call fields are actually inventions. They are made of lots of small (mini) true fields.
3. Each true field is emitted by each electron & each quark etc, in the conductor, & in the universe.
4. Each true field propagates in a straight line.
5. Each true field has a beginning but no end (fields go to infinity for ever).
6. In which case every conductor is full of true fields.
7. Nett fields are an invention.
8. Nett fields are zero inside the (metal) conductor (because some conduction (free) electrons move).
9. But the conductor is always full of (mini) true fields.
10. I see one comment that says that nett field lines should enter (or leave) the conductor perpendicularly. I think i agree.
You are absolutely right about fields being an invention, and also about the way that charges collect at the points! The reason I made this video (a LONG time ago!) was to help my students visualize the processes that lead to two basic outcomes: (1) the field strength inside a conductor in equilibrium is zero, no matter what the external field is and (2) that all the net charge resides at the surface. I was absolutely intentional about dodging the details, details that you are correctly point to. cheers!
Nicely explained....
Well explained. Thanks
wow did I just understand this topic in 6 mins I couldn't understand for the past semester, thank you very much.
Glad you found it helpful!
This was very clear, thank you.
Helpful !!....with subtitle...thnx
how can there be no charge inside if you made your gaussian surface small enough couldn't you enclose just a proton
?
I want to ask about the picture where you show us that one part is more negative and other part is more positively charged (cause the electron move from there). When you use that picture and use a Gaussian Surface, it is easy to tell that the net charge inside the surface is zero. Cause it is perfectly constructed that the positive and negative charges are reside one the edges. But is it true that the positive charges on the edges? what about the charges like in the center? I don't quite understand the transformation of the pictures...
Forget about this video. Listen to me. Lets say you have metal sphere and you place that metal sphere in an electric-field (as, for instance, bringing it closer to another charged body. This is called induction). When you place the charge-neutral metal sphere in the electric-field and your electric field is produced by a positive charge. What happnes is that the negative charges on your sphere try to be as colose to the positive-charge (external, whose electric field we are talking about) as possible and positive charges on the sphere will try be as far as possible from where the elctric field of the proton is coming. And so in this way, may be, half of your sphere has positve charge and half of your sphere (towards the positive-electricfield) has a negative charge. It is very simple, there is nothing mysterious about it. ( You would probably not see my comment but hopefully, it will help someone else!
hey man in my book it is stated that the electric field lines are perpendicular to the surface of the conductor because if it wasn't, there would be some tangential component of the field along the surface. Now the explaination given is that because of the component there will be force and the charges will move and as this cannot happen, there can be no tangential component. Whereas the explanation should have been that the charges inside readjust to counter the tangential component and hence only the perpendicular field lines would remain. right? btw thanks.
You should be my physics teacher
I made the video ten years ago. You wrote this comment two years ago. Yet here I am on a dark January afternoon going "awwwww, what a sweet thing to say!" Thank you!
"If there is a field, there is a force" O, no!!! There is only a force when a charge is in the field.
fair enough!
true, this is a hand-waving explanation, and you caught me out on this point of principle.
@@SharksfootSoup Haha, not a big deal.
I want to ask about the picture where you show us that one part is more negative and other part is more positively charged (cause the electron move from there). When you use that picture and use a Gaussian Surface, it is easy to tell that the net charge inside the surface is zero. Cause it is perfectly constructed that the positive and negative charges are reside one the edges. But is it true that the positive charges on the edges? what about the charges like in the center? I don't quite understand the transformation of the pictures...
I think you are asking about the change in the pictures at 3:25 where I go from showing big fat +s and -s all over, and just show little + and - at the edge. Am I right?
How come all the + and - have to be at the edges, and does that work for positives as well as negatives?
Here is how the argument works:
Suppose there IS some unpaired positive charge inside the body of the conductor. If that's true, then we know there must also be nonzero Efield inside the conductor. We know this because we can draw a Gaussian around the + charge; Q≠0 tells us ø≠0 so there must be some nonzero field inside the conductor, and that field will point away from the positive charge.
But remember, this is a *conductor* -- the charges can move. If we are talking about something ordinary like a hunk of metal, then there are free electrons that will travel "upstream" in the field -- toward the positives. As long as there is field there will be charge flow, and the charge movement will continue until there is no field. When is there no field? When the unbalanced charge is neutralized.
The only way this charge-balancing routine can be interrupted is if the field is in a NONconducting realm, and the only way this happens is when part of the Gaussian must be drawn in nonconducting turf. The only charges that require such a Gaussian are on the surface of the object. So the only place where charge can reside in equilibrium is the outer surface.
I hope that helps!
ds