The page you are reading is part of a draft (v2.0) of the "No bullshit guide to math and physics."
The text has since gone through many edits and is now available in print and electronic format. The current edition of the book is v4.0, which is a substantial improvement in terms of content and language (I hired a professional editor) from the draft version.
I'm leaving the old wiki content up for the time being, but I highly engourage you to check out the finished book. You can check out an extended preview here (PDF, 106 pages, 5MB).
When you want to draw a bright pixel on the screen, you point the beam of electrons in that direction and leave it on for a few microseconds. But how do you make a beam of electrons point in some direction? You could just move the whole electron gun, but this is going to be difficult since you have to move the gun really fast. To draw the pixels of the entire screen you need to sweep the beam of electrons left and right across the screen at a frequency of 40-100 [kHz].
The way a CRT does this is to through the Electric force which can deflect electrons left and right, up and down as necessary. Yes Luke, use the force, the electric force.
The TV signal that is transmitted over the air is actually telling you consist of the information The D-shaped monitor cables, are called VGA and a fluorescent screen, with internal or external means to accelerate and deflect the electron beam, used to create images in the form of light emitted from the fluorescent screen.
wps.aw.com/wps/media/objects/877/898586/topics/topic07.pdf