A conductor is defined as it has free electrons to move, but when non conductor attain charge, it would also have free electrons. so it should behave like a conductor or not?
121703
So I was recently wondering what happens to the excess charge when it is placed on an insulator or conductor e.g. rubbing two objects together. I know in the conductor the electrons are free to move whereas in the insulator they in general are not very mobile so the charge stays in a small region. But why does this happen? I know about the differences in insulator and conductor band structure, how is this related? Do the excess electrons become part of the band structure?  Thanks!
28449
As I understand these two statements:   An electromagnetic field gives particles charge A photon is a quantum of electromagnetic field   It must mean that a photon carries charge. But I guess it isn't true. Why not?
77403
Are they working with motion of electrons?
70758
So, recently while I was studying electric fields and charges for a test, I came across the definition of electric potential as -     The amount of work done in moving a unit positive test charge from infinity to a point, without changing its kinetic energy, i.e, without acceleration against the force due to an electrostatic field.   But this contradicts to what the work-energy theorem says, that the work done equals the change in kinetic energy. What am I missing here?  Also, what exactly is electric potential? Why can we only define a potential for a conservative field?
53691
I don't understand this..maybe there is something wrong with my understanding of battery or electricity.  I am learning about electricity more deeply this time. So please bear with me.  So lets begin with what I know:   follow of current occurs when there is voltage drop. voltage drop happens when there is imbalance in charge. a battery is basically two separated chemicals. One side with electrons to spare and other side that needs electron to balance itself. which is imbalance in charge. When both sides are connected + side snatches electrons from - side. (And if there is a medium, conductor, then first electrons are taken from conductor that in turn snatches from - side, which not being able to keep electrons lose them and give up those electrons, we label it as excessive.)   The analogy i was taught with used marbles in pipe... When one side has excessive marbles And this pipe is connected to other side that has no marbles the marbles will instantaneously start falling out so even though marbles from container with excessive marbles haven't traveled there yet, they still start falling because filled side marbles are pushing marbles in pipe and which in turn push the last marbles in pipe out.   1st, Aren't electrons pulled by atoms that can use more electrons, and not move because one side is overfilled with electrons so they can't wait to push some out.  Questions:    if I connect a conductor to positive side of a battery, shouldn't it make all electrons/marbles fall into empty container as empty container will pull marbles as atoms need electrons? if I connect two batteries' only opposite sides to each other shouldn't they drain (balance the each other out, cancelling all - &amp; + charges)?
29129
Since the electric field inside a conductor is zero that means the potential is constant inside a conductor, which means the "inside" of a conductor is an equal potential region.   Why do books also conclude, that the surface is at the same potential as well?
55997
This is something that has long bothered me, and I have asked a few physicists and chemists and never gotten a very satisfying answer. Why are particles charged? And I'm not asking (and this is the answer you often get) why some molecule might be negatively charged because the answer to that is simply is that there was one more negatively charged particle than positively charged particle. That doesn't answer my question, however, of why there are charged particles at all?  So, on a fundamental level, what makes one particle charged and another one neutral.  For instance, protons and neutrons have almost exactly the same mass, which I'm assuming that means they have very similar internal compositions, yet one is positively charged and the other neutral. What is going on that makes these particles different?  On a similar note, and I'd really like to know this, how is it that a proton and an electron have exactly equal and opposite charge, yet an electron is about 1000 times less massive than a proton?  I have particular trouble with this question because if the answer were something along the lines of "particle X which composes protons all have partial positive charges of n amount..." I would just ask why particle X has any charge and we'd be in the same predicament.  I'm sure there is a satisfactory answer to my question, I just can't find it and don't know what resources are reliable or detailed enough to be satisfactory.
101859
We could imagine a simple electronic circuit composed by a power source and a resistor.   It is usual find descriptions as "The moving charged particles in an electric current are called charge carriers. In metals, one or more electrons from each atom are loosely bound to the atom, and can move freely about within the metal. These conduction electrons are the charge carriers in metal conductors." (wikipedia ). That made me imagine electrons going from power -, running by the wires, crossing the resistor and returning to power +, where they suffer a new kick to power -. All that at near the speed of light.  In this model, it is easy to define "electrical current intensity" as proportional to the number of electrons per second that cross one specific point of the circuit.  However, looking for the physics of resistivity, I can read the phrase "The actual drift velocity of electrons is very small, in the order of magnitude of a meter per hour." (wikipedia ). This is a complete different point of view, where electrons are more or less fixed around a fixed position (or moving very slowly), an electricity is a wave of "collisions" or "jumps" of electrons, like in a Newton's cradle (or "do the wave" as public in a football match). Obviously, we do not need severals hours from the switch on to the light on.  So, the question is, do electrons move around a circuit ? References to band theory are welcome.  A related question is: if electrons doesn't moves along the circuit, what is "electrical current intensity"?  Note: I known there are similar questions already posted, but answers of the ones I've read are not very detailed (could be I've not found the best ones). Please, be a few patient before "close vote".
42606
According to :     The electron has no known substructure. Hence, it is defined or assumed to be a point particle with a point charge and no spatial extent.   Does point particle mean the particle should not have a shape, surface area or volume?  But when I searched Google for the "electron shape" I got many results (like  and ) that says electrons are round in shape.
33024
I read this in my textbook: A charged particle or object is not affected by its own electric field.  Since I find this completely unintuitive and my mind is yelling "wrong! wrong! how could a particle even distinguish between its own field and the external fields?" I would really like to hear an explanation about why this is true, if it is.  (A corollary question that comes to my mind after thinking about this is... What about gravity and mass considering the analogous situation? And the other two forces?)
116651
I've been wondering why silver is the best conductor of electricity for a while now, and I've observed that in Group 11 transition metals where silver is located, copper and gold too are also one the best conductors of electricity (Cu, Ag, Au are all in Group 11). I believe that Cu Ag and Au share some physical similarities that makes them a very good conductor of electricity as they are in the same group. More importantly, why is silver, specifically silver (not gold nor copper) the BEST conductor of electricity?
28377
How can AC provide energy if electrons don't have a net movement? In fact,  an electric instrument requires electrons to work, for example in a light bulb the electrons go across it. But in AC circuits electrons don't go inside it, so how can it work?
72246
The often told cause of conductor conducting electricity is their valence band and conduction band overlap and when an electric field is applied the electrons jumps into conduction band and electricity flows.I don' t get this how the jump of electrons from valence band to conduction band i.e,the next available energy band cause current to flow.I learnt electrodynamics using free electron sea model and now I am unable to harmonise the two.For example, Suppose we have sodium crystal which is a conductor.The valence band in this case will be the one due to 3s and conduction band  3p.How can a jump from 3s to 3p cause current flow?
113071
According to , a cathode is "an electrode through which electric current flows out of a polarized electrical device". However, the direction of current flow is purely an arbitrary convention, and is in fact the opposite direction to which electrons flow in a metal conductor. Hence, this definition seems to be a bit lacking.  If the definition is referring to the current carriers, then the definition might be rephrased as "cathode is an electrode through which the charged current carriers flow out" (or "in"?).  How would you define this term clearly and unambiguously? Does the common use of the term "cathode" really reverse when the current carrier is positive, as suggested in the article?    Edit: What actually confuses me is the phrase "Cathode polarity is not always negative". If electrons always flow into the cathode (by way of definition of cathode), this statement implies that the cathode can be at a positive voltage relative to the anode. Can this happen in a "simple" conductor like an electrolyte, or does this require some special circuit?
43576
It took me a long time to understand that current is constant throughout the circuit. And now I am stuck at one last thing: The speed of charge. Here is what I am thinking:  Current is defined as quantity of charge passing through a point at a given time, and from this we can deduce that current is constant throughout a circuit. But, if this is true, then wouldn't the speed of charge through a resistor be increased? Let us think about an analogy, water flowing through a pipe. Suppose water is flowing through a broader pipe(analogous to a less-resistance wire), and  a greater quantity of water can flow past a point because of larger cross-sectional area. Now, suddenly water encounters a smaller pipe(analogous to the resistor). So, less quantity of charge can flow through it because of less cross-sectional area. But, if the volume of water flowing in a time $T$(analogous to current) is same, won't the rate of flow of water in the narrower pipe(the resistor) be more?  I am asking this question because while seeing some answers for the question that "Why is current constant?" , I saw some people saying that speed of charge slows down a bit through a resistor, which seems incorrect to me.
28321
Even if the atom is neutral (equal numbers of protons and electrons), the electrons and nucleus form an electrical dipole, so there is still an electric field around them, even though the total charge is zero. Is this reasoning correct? So, every atom has an electric field, even if it is too weak? If not, why?
28037
If current is the rate of flow of electrons past a point. Let's say a wire is full of electrons, and of course they pretty much are already going the speed of light, minus friction. What would increasing the voltage do?   You can't go faster than the speed of light, and you can't increase the rate of electrons because no more fit in the tube. I am just curious what this would look like. I feel like I am missing a key concept.