What does sigma represent? The surface charge on the outside of the cylinder? If so, then sigma/epsilon is correct.madah12 said:ok another question in this case of a wire inside a hollow conduction cylinder is E at the surface of the cylinder equal only to sigma/epsilon naught or is it (lamba * l + sigma *A)=E*A? because the book says the field on the surface of the cylinder is sigma/epsilon
That's right. And if the cylinder has no net charge of its own, the field outside its surface will equal that of the line charge.madah12 said:yes sigma is the outer surface density ,so I understand so you are saying that because on the inner surface there is q induced that is equal and opposite to the one of the wire?
so even outside the surface of the cylinder Q only equals sigma outer *outer surface area?
In that problem statement, sigma represents the total charge per unit area on the cylinder, not just the charge on its outer surface. (The problem is confusingly worded.) Think of sigma as the charge on the outer surface before the line charge is introduced. Once you include the induced charge due to the line charge, then the outer surface will have zero sigma.madah12 said:http://physics.kuniv.edu.kw/phys102/08-09-S-ms1.pdf
look at number 5 how can the field be zero if Q=sigma *a
I imagine that means the total charge per unit length. (As opposed to the surface charge, which is per unit area.)madah12 said:so sometimes they say the linear charge of a cylinder do you know what that means?
This refers to the fact that when an electric field is applied to a conductor, the charges inside the conductor will rearrange themselves in such a way that the resulting electric field inside the conductor is zero.
This is due to the properties of conductors, specifically their ability to allow charges to move freely. When an external electric field is applied, the charges inside the conductor will rearrange themselves in such a way that the resulting field is zero in order to reach equilibrium.
No, there can still be electric field lines present inside a conductor, but they will cancel out each other due to the rearrangement of charges, resulting in a net electric field of zero.
The absence of an electric field inside a conductor means that charges will not experience a force, and thus will not move. This is why charges tend to accumulate on the surface of a conductor when an external electric field is applied.
In some cases, if a conductor is not a perfect conductor (e.g. has a finite resistance), there may be some residual electric field inside the conductor. Additionally, in the presence of time-varying magnetic fields, a phenomenon known as electromagnetic induction can cause an electric field to exist inside a conductor.