Question

On a systems level, as electrons are pushed into a wire, there is a net field and a net electron velocity. And the net electron drift is slow. But electricity travels through the wire, essentially at c, and I want to understand that mechanism. I know bare bones undergraduate quantum theory circa 1990s but it doesn't explain the motion of electricity in detail. An electron moves into the wire. It's got a kinetic energy. After travelling a short distance, it spontaneously emits a photon, which hits another electron in a valence shell. That electron then presumably does the same. Presumably at this level, electrons are acting more like waves and less like particles, but is there any classical component in the picture, ie are electrons coming in imparting other electrons with kinetic energy through repulsion, or does it not work that way?

Answer 1

Electrical signals travel through wires rapidly due to the propagation of an electric field, which occurs near the speed of light, while individual electrons drift much more slowly. Electrons move in a zig-zag fashion because of collisions within the conductor, and it is the free electrons that primarily contribute to electrical conduction.

Step-by-step explanation:

Understanding Electrical Conduction in Wires

When we talk about electricity traveling through a wire, we are referring to the flow of electrical current, which is the movement of charges (in this case, electrons) through the wire. Despite the electrons themselves having a low drift velocity, typically on the order of 10-4 m/s, the electric field that drives the current propagates at a much higher speed, close to the speed of light. This rapid propagation allows electrical signals to travel long distances almost instantaneously, enabling telephones and light switches to work without noticeable delays.

The individual electrons in a conducting wire do not move at constant velocities but instead drift in a zig-zag fashion due to repeated collisions with atoms, other electrons, and impurities. During these collisions, energy is transferred to the conductor's lattice, usually leading to an increase in temperature. The concept of free electrons helps explain conduction: these are electrons that are not tightly bound to any particular atom and can move freely through the metal's lattice structure, thus carrying the current.

It is the applied electric field that imparts energy, allowing free electrons to accelerate and move through the conductor. While an electron may transfer energy to the atoms and lose potential energy, it doesn't continue to gain kinetic energy; instead, it reaches a steady state known as the drift velocity. The overall rapid transfer of electrical energy along the wire is due to the electric field affecting many electrons nearly simultaneously, rather than from the direct transfer of kinetic energy from one electron to another.