cnh1995 said:
Their poles near the walls cause the electric field inside the dielectric.gracy said:
gracy said:
Well that's the overall picture of how it works. Its not in proper physics language so I guess gneill or some other expert will later come up with a way better explanation. Until then, hope this is fine.gracy said:
I'm not sure if "nullify" is the proper word here. I believe it should be "attract".This structure forms a resultant single large dipole that opposes the field due to the plates. Think of the dipoles as batteries connected in series. Their voltages will add and across the two far ends, this total voltage will be available. Similarly, the fields of the dipoles will add and the resultant field will be available inside the dielectric ,opposite to that of the plates.cnh1995 said:
Consider left blue column. Its +ve poles will nullify the effect of the -ve poles of the next column. This will go on till the last column(rightmost blue). The +ve poles of the last column and -ve poles of the first (leftmost blue) column will create the electric field inside the dielectric which will be opposite to the one created by the plates.
It is just showing that the dielectric material has no bulk volumetric charge density, but does have a surface charge density.gracy said:
The effect of introducing a dielectric - with its easily polarised molecules is to increase the Capacitance between two conductors (plates). That means the charge difference between the plates will be much greater for a given PD across them. The charges on the faces of the dielectric - and the charges on the plates - correspond to what you would get if the plates were much closer together in air. The practical advantage is that a thick layer of insulating dielectric will allow a much greater operating voltage (hence a greater stored charge for a given capacitance) and reduce the requirement for the plates to be accurately flat (i.e. the percentage accuracy of the spacing for the area). The 'ease' is proportional to εr (>1) because, of course, the hardest is a vacuum (εr = 1). The easiest is a metal conductor. Unfortunately, a conductor will polarise with no PD across it and allow the charge to pass through it so you would also need an air gap in series, to use it in a capacitor.gracy said:
Suppose the field established by the charges on the plates is Eo and there is no dielectric, just air(or vacuum). Now if a dielectric slab is inserted, it will be polarized and create its own opposing field E1 which will reduce the net field strength in the dielectric.gracy said:
εr=χe+1.gracy said:
Something is called easy when a result can be achieved with less effort. In this case the result is the polarization of the material which in turn determine total electric charge stored in a capacitor while the effort is the potensial required to polarize the material for required quantity of electric charge.gracy said:
And how it (susceptibility)does that?I know it is property of a material but how susceptibility contributes in polarization of a material?nasu said:
"How"? Do you mean the mechanics of the material?gracy said:
I believe that depends on the "chemistry" of the material. There are various types of polarization e.g. dipolar , electronic, ionic polarization etc.gracy said:
I would say susceptibility doesn't do that but the materials do, by means of their chemistry and applied electric field. This behavior of the materials to respond to the applied electric field is quantified by "defining" what we call as their "susceptibility". It is a constant "determined" as the constant of proportionality in the experimentally obtained equation, P∝Enet.gracy said:
I don't think that this question is what you want to ask. Susceptibility is simply defined this way, so the question is a little like asking how mass makes a particle more difficult to accelerate.gracy said:
Right. But permittivity gives the relation between net field and the original field while susceptibility gives the relation between polarization and the net field. So, according to my understanding, permittivity tells you how "strong"(may not be the correct word) a dielectric is w.r.t vacuum( free space) while susceptibility tells you how sensitive a material is to the applied electric field. Susceptibility is a general term and doesn't depend on vacuum. But permittivity is first defined for vacuum and then applied to all the other materials (using relative permittivity or the dielectric constant).gracy said:
Yes.gracy said:
Yes. That is what happens in capacitors.gracy said:
Yes. ε=εoεr. In case of vacuum, εr=1, so there's only εo in the formula.gracy said:
Conductors are extreme cases of permittivity and susceptibility.gracy said:
##ε0##=##\frac{σ}{E}##cnh1995 said:
Right.gracy said:
gracy said:
cnh1995 said:
There will be field lines from +ve charge density towards -ve charge density "through" the surrounding. It is similar to what happens inside a capacitor.gracy said:
Yes. The charge densities act as a dipole. So, there will be field lines in the surroundings, joining the two charge densities.gracy said:
But it is permittivity of free space that tells us how "strong"(may not be the correct word) a dielectric is w.r.t vacuum( free space) if we look at permittivity of other materials how it differs from their susceptibility?cnh1995 said:
No. I said it is the permittivity of the material, not free space.gracy said:
You meant relative permittivity?cnh1995 said:
I meant actual permittivity(ε) of the material(εoεr).gracy said:
Right.gracy said:
Yeah right. I meant the concept of permittivity (relative permittivity is a part of that) compared to the concept of susceptibility.gracy said:
