What you say, ("current is established everywhere at the exact same time") cannot happen. Not as soon as the switch is closed, and not at any instant after the switch is closed either. The current cannot be established everywhere at the exact same time period because it would imply that a signal travels faster than the speed of light. Try to imagine the circuit to be made of water troughs, water wheels, and a water pump. When the pump is turned on, a pulse of water will propogate along the circuit and the water wheels will not all start to spin at the same time but rather one by one as the initial pulse hits them . Electrical fields aren't that much different, just faster.whozum said:Thus current is established everywhere at the exact same time (but not instantly after the switch is closed).
Once the field is established (very soon after the swithc is closed) electrons from all over the wire begin moving, not just at the very beginning of the wire. This is why there is current flowing everywhere once the field is established. This is why the bulbs all turn on at the same time.chroot said:To start with, when you connect a battery to a capacitor, the electric field propagates through the wires at nearly the speed of light. It has nothing to do with the movement of any electrons; electrons, in fact, drift only very slowly through a circuit. The electric field which propels the electrons, however, propagates at near light speed.
The current is not like a gush of water coming down a mountain, moving from one place to another -- the current is like a conveyor belt that gets "turned on" everywhere at once in the circuit as the emf (voltage, potential difference) is established through it.
Of course there is always a potential accross the battery, where do yo think the potential accross the open switch came from? All closing the switch does is transfer that potential to across all three light bulbs.jdavel said:switch closes that's where the potential difference is.
Before the switch closes, there's no potential across the battery (if there were, current would flow through the battery). So it doesn't matter which bulb is closest to which battery terminal.
I like this explaination but it doesn't address "very soon after the switch is closed" who gets the info first to turn on first and what is that info.whozum said:Once the field is established (very soon after the swithc is closed) electrons from all over the wire begin moving, not just at the very beginning of the wire. This is why there is current flowing everywhere once the field is established. This is why the bulbs all turn on at the same time.