How did an electron beam form an image on a cathode-ray tube screen?

In a cathode-ray tube (CRT), an image is formed through the precise generation, control, and scanning of an electron beam against a phosphor-coated screen.12

The process functions as follows:

• Generation: An electron gun at the rear of the tube contains a cathode coated with oxides of barium and strontium. When heated, these materials emit electrons.34
• Acceleration and Control: A positively charged anode draws these electrons forward. A control electrode regulates the number of electrons passing through an aperture, which modulates the brightness of the resulting spot on the screen based on the incoming television signal.34
• Focusing and Deflection: The beam is accelerated toward the screen by high voltage and focused into a fine point. Magnetic or electric fields then steer this beam to scan across the screen surface.564
• Image Formation: The inside of the display screen is coated with phosphor materials. When the electron beam strikes these molecules, they emit light (phosphorescence). By scanning the beam at high speed, a complete image is rendered.264