> And in electronics, I assume that the boundary of the conductor with non-conductor (e.g. air) provides a similar function. Electricity inside a conductor wor

> And in electronics, I assume that the boundary of the conductor with non-conductor (e.g. air) provides a similar function. Electricity inside a conductor works more like a sound wave the article talks about than optical fiber. It's not coherent or directed, you have a high "pressure" on one end pushing the electrons, and they push each other forward as a consequence. There is no care about reflections (up until radio frequencies), it just moves into the direction of less "pressure" through the medium. (Even in RF, but on those the reflections cause noise.) Optic fiber depend a lot on conservation of momentum. Electrical current has none of that. Even the reflections are caused by the "elastic absorption" of the medium, and don't behave like a collision. > I've heard that conductors conduct almost entirely on their surface That's not really right. Conductors conduct through all of their area, unless you have high frequencies. At high frequencies there is magnetic interaction between the electrons so they are pushed out of the conductor's center, but this is not a universal thing. And then, in high frequencies you don't use hollow tubes. You use thin wires, insulated from each other, knitted in a way that every wire spends the same length on the middle of the bundle.