The model can be applied to positive (hole) charge carriers, as demonstrated by the Hall effect.

There is only one type of charge carrier present.

Magnetic forces give information about the charge carriers in a material through the Hall effect.

As you probably already know, in order for anything to conduct electricity, there must be some mobile charge carrier.

So we can imagine that pure ice having no charge carriers would also be a poor conductor.

Therefore, on average there will be no overall motion of charge carriers in any particular direction over time.

The influence of free charge carriers is often (but not always) unwanted, and various means have been proposed to remove them.

This results in only a small number of effective charge carriers.

In a vacuum, free electrons can act as charge carriers.

This effect is proportional to the mass of the charge carriers.