Video Transcript
The picture shows the electrons and
atomic nuclei in a section of copper wire. The blue circles represent
electrons and the red circles represent atomic nuclei. At first, there is a buildup of
electrons at the right-hand end of the wire. What will happen in the wire over
time?
To begin, let’s think about how
there came to be a buildup of electrons in the right-hand end of the wire. Usually, the electrons in a
material are evenly spread out, like this. But if work is done on the
electrons, they can be moved toward one end of the material like this. Note that the atomic nuclei are
fixed in place, so they don’t move with the electrons. But what happens when we remove any
outside influence on the wire and let it return to its natural state?
First, let’s point out that we’re
looking specifically at copper wire. Copper is an excellent conductor,
which means electrons can move through a copper wire really easily. Next, let’s remember that electrons
are negatively charged particles. We should also recall that
particles with similar charges repel each other. This means that when two electrons
are close together, there will be a force between them that pushes them apart. When there are lots of electrons
close together, these repulsive forces between them cause them all to spread
out.
Here, there is a buildup of
electrons at the right-hand end of the wire. So these repulsive forces would
cause the electrons to move towards the left-hand end of the wire and away from the
right. The electrons will continue to move
towards the left until they are once again evenly spaced out in the wire. So this is the answer to the
question.
Over time, electrons will move
toward the left-hand end of the wire until they are spaced out evenly.
