B Tangential part of the potential electric field

[FrankygoestoHD]

Good afternoon to everybody. I have may be a stupid question according to the tangential part of the electric field near the surface of the conductor. Why is it zero? The normal part is zero on the distance of Debye cause of screening. But is this situation the same for horizontal direction cause of the charge, pulled by this part of the field and no place for emission of electron to another place?

 

[vanhees71]

I think you talk about electrostatics. Then indeed the electric field has a potential and the tangent component of it must vanish, because by definition a conductor consists of a material containing charges (usually electrons, at least for metals) that can move quasi freely within the material. This means that if there where a component of the electric field tangential to the surface of a conductor these conduction electrons would be set into motion due to the electric force in that direction, and you'd have an electric current flowing, but then you are out of the realm of electrostatics. The normal component of the electric field can be non-zero, because the conduction electrons are bound to the conductor. Of course, if you make the external electric field too strong you can free those electrons overcoming the binding energy, but then you also leave the realm of electrostatics, because again an electric current would flow.

 

[FrankygoestoHD]

I think you talk about electrostatics. Then indeed the electric field has a potential and the tangent component of it must vanish, because by definition a conductor consists of a material containing charges (usually electrons, at least for metals) that can move quasi freely within the material. This means that if there where a component of the electric field tangential to the surface of a conductor these conduction electrons would be set into motion due to the electric force in that direction, and you'd have an electric current flowing, but then you are out of the realm of electrostatics. The normal component of the electric field can be non-zero, because the conduction electrons are bound to the conductor. Of course, if you make the external electric field too strong you can free those electrons overcoming the binding energy, but then you also leave the realm of electrostatics, because again an electric current would flow.

Thank Tou very much for your answer ! That was i was thinking about.