# Tag Info

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There are very few materials, which show real Ohmic behavior, most materials the resistance is dependant from temperature , so the resistance changes with the current heating the wire.

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The macroscopic argument is that, if there is a field inside the conductor, the free charges in the conductor will move, sothe only situation compatible with steady state is one where there is no field inside and all the charges are redistributed on the physical boundary of the surface. The more microscopic argument - which involves the conductivity - is ...

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The way I understand it (which may not be entirely correct, but I'm gonna take a shot at this), electrical permittivity measures the ease at which electric charge can move through a material, and thus how polarizable the material is. Therefore, the charge contained inside some area in the material actually depends on $\epsilon$. I would guess that, if you ...

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it has to do with voltage differences at sharp corners of the object, It's not voltage differences. It's electrical field strength. When the electric field strength exceeds the breakdown value for air, you'll get a spark. And the field strength tends to "concentrate" at sharp corners of electrodes. But these are general principles that apply in lots of ...

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The simplest proof is that for a conductor the current density inside the conductor is given by: $$\mathbf J = \sigma \mathbf E$$ where $\sigma$ is the conductivity and $\mathbf E$ is the field inside the conductor. At equilibrium the current density has to be zero everywhere inside the conductor, and this is only possible if $\mathbf E$ is zero ...

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Consider a point charge placed at the center of a metallic shell. We can draw a Gaussian surface enclosing the charge, and thus, the field inside cannot be zero. If you are saying you'd make the Gaussian surface between the outer and inner surfaces of the conductive shell, you're neglecting the separation of charge in the conductor. When you place the ...

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Current is related to the speed of electrons but it is not the speed of electrons! Current is the amount of charge that passes through a cross sectional area in one second. Relating current solely by the speed of free electrons is wrong. Current is given as $N \times A \times V \times E$ where: N is the number of free electrons per unit volume A is the ...

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In a static situation, there can be no field inside a conductor. If there were, charges would move until there was no field. This means that every point within a conductor (including points on the surface of an empty cavity) is at the same potential. This in tern means there can be no field inside the cavity.

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