# I Physics of electric current

1. Aug 1, 2017

### davidge

Electric current can be studied using classical electromagnetism. In that case, the explanation is that there is a net flow of free electrons through a wire, say.

Looking more close on the situation, what happens is that there is a difference on the energy level of some atoms and electrons can flow from one to another. -- Excuse me if I'm wrong at this point.

Anyways, my question is, Is it appropriate to explain the phenomenon of electric current using quantum mechanics? Maybe, the electrons get excited and jump off from one energy level to another one?

2. Aug 1, 2017

### Staff: Mentor

Electrons are not part of classical electromagnetism. They are part of quantum electrodynamics.

3. Aug 2, 2017

### ImNotOliver

Electric current is the flow of electrons on the surface of a wire, or other conducting surface. The energy levels of individual atoms within the wire really don't effect the electric flow unless they become so excited that electrons are knocked free.

The flow of energy from one atom to another does not happen through electrical current. If one atom collides with another, it can transfer momentum the same as any two colliding bodies. On the quantum mechanical level, an energetic atom, wanting to be in its lowest energy state, will emit a photon. A second atom can then absorb that photon, thus transferring the energy of one atom to another.

4. Aug 2, 2017

### NFuller

Yes this is the premise of band theory for solids. If the conduction band and valence band overlap then the material is a conductor. This is because there are open states just above the ground states of the valence electrons (the spacing between states is generally on the order of $10^{-22}$eV). This means that even a tiny electric field can get electrons to jump into a slightly higher energy state where they can move through the material.