I was discussing lightbulbs the other day, and suddenly we realized that we don't know what resistance is.

 

I know the V = I*R laws and other basics. I know that the wire in a lightbulb glows bright because all energy of electrons is lost in the wire because it is thin and therefore has a (relatively) high resistance.

 

Let's look at a DC current in a wire (or any other resistor, they all just heat up to dissipate the energy).

 

So, these electrons entering the wire lose their energy somehow. I'm visualizing it as high energy electrons in the valence band getting too close to another electron in the valance band, pushing the next one forward. That one in turn pushes the next. However, I fail to see where they lose energy in this pushing each other and the ions on the lattice around. These valence electrons must somehow cause increased thermal motion on the ions...

 

Rather disappointingly wikipedia says this (disappointing because don't understand it ):

 

Near room temperatures, the thermal motion of ions is the primary source of scattering of electrons (due to destructive interference of free electron wave on non-correlating potentials of ions), and is thus the prime cause of metal resistance. Imperfections of lattice also contribute into resistance, although their contribution in pure metals is negligible.

Electrons can collide with other electrons or they can collide with the atoms in the metal. Collisions cause accelerations, and anytime charges accelerate they radiate energy, and energy given up to the atoms (ions) shows up physically as increased vibration, and manifests itself as an increase in temperature, which (going back to the radiation again) is a loss of energy.