In an electric circuit, how does the excitation of the free electrons to higher energy levels translate into net forward motion of the electrons to the positive terminal? My concept of electrons being excited by the electric field is that they have a higher orbital but they are still localized around the nucleus of a few atoms (especially in a more resistive element). But I know there must be a small net forward motion for there to be current.
I need to marry the classical model of the colliding electrons and atoms of the medium with the Quantum principles involving the excitation of charges to higher energy bands and emission of photons.
Also, a second question is what causes the electric field in the conductor to be practically zero (compared to that in the resistor) in a non – electrostatic model (i.e., when there is a current).
Thank you so much for your help. I have scoured the internet for insight but I have not found a site that marries the classical to modern theory clearly for me.
Best Answer
There are bound electrons and there are free electrons - the former interact with radiation and electric fields and the like by bouncing around energy levels and emitting photons (dissipating energy, as in a resistive element), the latter do actually move around and are strictly not localized around the nucleus of a few atoms, and largely preserve energy through a wire, for example.
There is no inconsistency between the quantum model of bound electrons and the idea of a free electron - the latter just has its own quantum model (:
The electric field is definitely 0 in a conductor. Not sure why Steeven seems to think that current would stop flowing without the presence of a net field. It doesn't take any energy to move electrons through a voltage drop of 0 as is the case in a wire. They just keep moving along to prevent charge building up. You could think of it really loosely as the maintenance of flow/average velocity through some horizontal segment of plumbing. It's not due to any net gravitational force (electric field) the water is (electrons are) subject to in that area, it's just maintaining the conservation of density (charge) at the ends, where other things are going on.