# Inductor rise time and inductor wire length

So here is an interesting question about inductors or coils in general.

Suppose you had a inductor which was 12 inch's in diameter and say 12 inch's in length and has 100 turns of wire. The total length of that wire would be 12(diam) x 3.14(pie) x 100(turns) = 3,768 inches/314 ft in length.

So if you apply a voltage across the coil, I assume the time needed for the current to start moving in the whole coil would about the time needed for the signal to traverse the length of the wire which would take about 314 nanoseconds at 1 ft per nanosecond. Otherwise if the electric field from the first wire just permeates out from wire to wire, then it would take a max of 1 nanosecond before the current in every wire was moving.

So which is it? Does the electric field need to move through all of the 314 ft of wire before the current is moving at the end of the coil or does electric field move through the length of the wire and ultimately cause the current in the end of the coil to start moving after 1 nanosecond?

At the short timescales you speak of, inductor actually looks from a circuit standpoint more like a distributed $LC$ ladder network like the one I have drawn as part of the system at the end of this answer. A complex system of bi-directionally running waves bounce back and forth through the system and eventually all these transients die down to establish the inductor's steady state behavior.