Why do electrons “actually” move from the negative to positive terminal of the battery?

It is likely that the questioner has been taught that electricity is the “flowing electrons”. The question is about electron flow.

The FLOW OF ELECTRONS is not electricity, but rather, it is electric current.

It is the apparent flow or electric charge.

Although electrons have a negative charge they are not moving. Like charges repel, electrons will move away from a negative charge that is near them. However, there are trillions upon trillions of these electrons in a conductor. The negative charge that we bring into the conductor does not cause trillions of electrons to flee, as they all repel each other equally. The electrons actually redistribute their energy so that they are as far apart as possible from one another. This redistribution is a very small movement. Each electron moves the minimum distance necessary to reach equilibrium with the electrons around it.

A crowded room is an analogy. Everyone moves about trying to maximize their personal space. Everyone is now at an equal distance from each other after a while. Then another person enters the room. People begin to reorganize themselves in order to accommodate the newcomer. A “wave” of shifting ensues throughout the crowd as everyone adjusts. After a while, equilibrium is restored.

The original charge that started the redistribution of electrons effectively propagates through conductor. Each electron feels the influence of its neighbours and adjusts its position accordingly. This in turn affects other neighbours. The conductor moves at the speed light, spreading the “knowledge” that an electron was brought to bear by a charge on one end. The electrons themselves, however, have not moved at all.

The hosepipe analogy is a favorite of mine. Imagine a transparent garden hosepipe filled with marbles. Pushing a marble into one end will cause another marble to fall out of the other. It’s almost as if the marble that you have added has exploded through the hose, appearing at the opposite end. Because all marbles are identical and it’s impossible to see through the hose, you won’t be able to tell that this isn’t what happened. Instead, the force was transmitted through all intermediate marbles, dislodging one at the end. The force is transmitted at speeds far greater than those marbles actually move. In fact, it would travel at the speed sound in glass if glass marbles were used.

Applying a negative charge at one end of a conductor would be like adding marbles on a hosepipe. While the electric field’s force propagates through conductors at the speed light, the electrons that help facilitate it, just like the marbles, remain almost where they are. A circuit is necessary for current to continue flowing. Otherwise, you are just adding static charge. Marbles need a circuit or at the very least a force gradient to work. If you push at both ends of a hosepipe equally, nothing happens. The force applied to a marble at one end causes it to fall out. The same applies to conductors. A current can only flow when there’s a charge gradient or force. This is called the electromotive force (EMF). This is measured in volts.

An electric current can be defined as the flow or movement of negative charges from one end to the other. It could also refer to the flow or movement of positive charges, from one end to the other. While electrons facilitate the charge in a metal conductor like a semiconductor, electrolyte or battery, other charge carriers such as ‘holes and ions can also create electric currents.

It is interesting to see how slowly electrons move in conductors. This electron drift does not correspond to the current Drift velocity. Wikipedia

. Although it is caused by the EMF applied, it is much slower than the current. An electron moves at 25 microns per second in a 2mm square copper cable carrying one amp. This means that an electron can take over an hour to travel 100mm from one end of a piece of this wire to the other. It’s clear that electricity is not the flow of electrons, despite what your high school teacher may have said.

The bottom line: Electricity can be more bizarre than you think.

LEAVE A REPLY

Please enter your comment!
Please enter your name here