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I know that in an electrostatic situation electric field inside a conductor is always zero and according to gauss law there cannot be a net charge inside a conductor all charge must reside outside.

What about the situation outside i.e. on the surface of conductor where there is charge is there an electric field outside as well i.e. is charge experiencing a net electromagnetic force why doesn't charge leave the conductor surface what causes it to stay on the surface is it because conductor is rigid is it due to force of nucleus or due to the force outside of medium ie air ?

E.g. consider a neutral conductor insulated from all sides and a glass rod with positive charge is brought closer to it why dont electrons move towards it completely?

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I'll do a handwavy explanation here. What makes a metal a metal is the fact that the electronic structure within the material is such that the electrons can move about relatively freely. This property comes from the type of nuclei and their specific arrangement and can be calculated using sophisticated numerical methods.

But this property ends at the edge of the metal, because - of course - this structure is only present within the material. So you would need a lot of energy (how much depends on the material), to take an electron out of the bulk, since the electron being inside is energetically ususally a lot more favourable.

If the field is strong enough (e.g. at sharp tips), electrons can actually be ripped out of the metal, which is called field electron emission. But, typically, this takes very high electric fields.

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1)Take the case if a van de graff generator.The surface keeps on building charge till the electric field becomes strong enough to ionise the air (3Mvper meter) and render it conducting after which the charge starts leaching out and doesnt build up. 2)Every metal has a work function ie the energy needed to eject an electron.Till this energy is supplied the electron will not eject. 3)A charge doescnot experience force due to it's own field.It will eject in the presence of an external field.

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