The discussion revolves around the behavior of electric fields within a conductor, particularly in the context of a problem from an MIT physics assignment. Participants are examining why the electric field inside an uncharged conductor is considered to be zero, despite initial assumptions that this might only apply when the conductor is charged.
The conversation is ongoing, with various interpretations being explored regarding the nature of electric fields in conductors. Some participants provide insights into the behavior of charges and the concept of equilibrium, while others seek clarification on the assumptions being made about uncharged conductors.
There is a focus on the conditions of static equilibrium and the definition of an uncharged conductor, with participants noting the implications of charge distribution and movement within the material.
The charges in the conductor are free to move in response to even the slightest electric field. So, if the field inside the metal was not 0, the charges in the metal would keep moving in response to the field until it was reduced to 0. Since the charges cannot go further than the surfaces, that is where they must reside.flyingpig said:It says that the E-field inside the metal is 0. Why? I thought that only applies when it is charged. This metal is uncharged
flyingpig said:...
It says that the E-field inside the metal is 0. Why? I thought that only applies when it is charged. This metal is uncharged
SammyS said:No. The E field in a conductor is 0. Even in the case when the conductor is charged.
How would adding a charge to a conductor in which the E field was non-zero -- perhaps even an itty-bitty charge -- suddenly make the E field become zero?
Exactly. A simple application of Gauss' law shows that all the charge must reside on the outer surface of the conducting sphere.flyingpig said:No, not adding a charge. Charging it would create a quick external field and such that the charges then will align themselves to zero the field inside and leaving the excess charges on the surface.
You had that problem too? I thought maybe my computer was biting the dust.flyingpig said:Isn't this all under the case of static equilibrium? How do we always know it is under equilibrium?
PF's lag prevented me from responding the last two days...
flyingpig said:No, not adding a charge. Charging it would create a quick external field and such that the charges then will align themselves to zero the field inside and leaving the excess charges on the surface.
flyingpig said:No but we are talking about when the charge isn't introduced yet, when it is uncharged
SammyS said:There is zero net charge everywhere, the conductor being neutral. Why would there be a field within the conductor?
SammyS said:If you charge the conductor itself, all the excess charge goes to the outside surface.
If the net charge was not 0 then it would not be uncharged. An uncharged conductor means that there is 0 net charge in or on the conductor.flyingpig said:Sorry to bring this up now
If the conductor was uncharged, the charges are still bound to move, the net charge wouldn't be 0 right?
I don't follow what you are saying there. An uncharged conductor is one that has equal number of + and - charges: net charge = 0. If those charges move around randomly inside the conductor due to thermal motion, that does not change the total charge. An uncharged conductor with no external field has 0 field inside the conductor. There may be microscopic motions of charges due to electric fields create by local anomalies, but macroscopically the field is 0.It is only that I charge it that I create an external E-field to make the field inside the conductor 0. When it is uncharged the charges are all still chaotically moving