Assume that in some materials that there are some electrons that are not attached to a particular molecule, but can move more or less freely in the material. We call them non-localized. These must be electrons that sit in the outer shells of atoms, and can’t decide which atom they are attached to.
Assume that in some materials that there are some electrons that are not attached to a particular molecule, but can move more or less freely in the material. We call them non-localized. These must be electrons that sit in the outer shells of atoms, and can’t decide which atom they are attached to.
When an electric field is applied to the material, these electrons start to accelerate, with a force eE, so an acceleration a=F/m=eE/m. If they were completely free, they would continue to accelerate across the whole material and the time to arrive at the far side would be proportional to ?1/E, from s=at²/2 .