Question

Can someone explain what happens when there's an inelastic collision between and electron and an atom?

Answer 1

This is a double-edged sword. If you want the painful details of electron collision with atoms, then I have to refer you to a QED text. However, if you want something superficial, then all you need to do is imagine that an atom is like a billiard ball. An electron carries kinetic energy (KE). Upon collision with an atom, the KE is transfered to the atom. Depending on the KE that is transfered, the atom now is in an excited state.

Answer 2

Thank you!