How does a CRT focus an electron beam? I get the basics of it. But I'm a little confused on the details. For electric focusing, how does accelerating the electrons cause it to focus? I'm looking for a more mathematical treatment of the subject. Everything I've found is just descriptive. For example, I supposed I'd like to know what the electric field looks like between the plates, grids, anodes, etc? What are the shapes of the plates, grides and anodes? How is the potential difference set up and measured? I know there are lots of variations of CRTs, but I am interested in the specifics of how they work (so pick your favorite type to discuss). Any information you could provide would be greatly appreciated!