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An electrical conductor creates a region in space that is devoid of internal electric fields. An electric field contains stored energy, with the density of that energy proportional to the square of t …

No, all water has a small spontaneous rate of generating ion pairs. There is a fresh supply of ions generated as long as there is water, so it is only when the water all leaves the system that condu …

Grease is a composite material. Some electrical greases are loaded with conductive particles (silver, copper, graphite). Other electrical grease and 'contact enhancing' coatings employ semiconducto …

So, 'no electric field' is correct for electrostatics, and not for a variety of interesting technology where current flows in conductors. … The field really IS small, so it's a good approximation even for current-carrying conductors. this seams to assume that there always is "enough" charge to redistribute. …

Excess charge applied to a conductor will reside on the outer surface of that conductor, but current in wires does not result from excess charge. There are very many mobile electrons ALREADY in a wire …

A wire is used to conduct electricity along its length. So, in normal usage, with all current parallel to the axis of the cylindrical wire, the electric potential is a function only of the length di …

Yes, of course a positively charged object can have a negatively charged surface. Consider a hollow sphere of metal,charged A, with an insulated positive-charge, B, inside the hollow. The exterio …

Force is a vector quantity: vectors add in predictable ways, so forces are capable of being considered separately or of being added together. We say 'superposition' if force fields (vector fields of …

Yes, as you suggest, edge current density is greater than center-of-foil current density. Skin effect comes from the magnetic field that a current generates, and which impinges on adjacent conductive …

It's all about heat buildup. A superconductor will, occasionally, lose coolant and quench, and you need enough conductivity of the windings to prevent that quench event from melting, straining or ot …

The E field near a smooth ideal conductor is always perpendicular to the surface element, because conduction nulls the lateral voltage gradient, and the E field is in the direction of the voltage grad …

Intrinsic semiconductors have a dissociated population (a bunch of holes and electrons that separate due to temperature, and can contribute to conduction until they recombine). Because a high popula …

The flow of current moves electrical charge. At endpoints of a 'broken circuit', charge would arrive and... sit. But, like charges repel; very rapidly, the accumulation of electrons creates an elec …

The high electrical current in a lightning strike delivers heat energy along the full length of the lightning bolt. Part of that length is in the ionized air over the plane, part is the plane's fuse …

Yes, you can capacitively couple to a conductor and induce currents. Those currents, though, are not flowing in a circuit, but are constrained by the conducting sphere to only flow back-and-forth on t …