How did cathode-ray tubes create images on television screens?

A cathode-ray tube (CRT) creates images by using a focused beam of electrons to "paint" a picture onto a screen coated with phosphorescent material. The process relies on several key components and physical principles:1

• Electron Generation: At the rear of the tube, an electron gun contains a cathode coated with oxides of barium and strontium. When heated, this cathode emits a cloud of electrons.23
• Acceleration and Control: A positively charged anode draws these electrons forward, while a control electrode regulates the number of electrons passing through based on the incoming television signal, thereby determining the brightness of the resulting spot.23
• Focusing and Deflection: Once released, the electron beam is accelerated toward the screen by high voltage. The beam is steered across the screen using magnetic or electric fields, allowing it to scan the entire surface.13
• Image Production: When the high-speed electrons strike the phosphorescent screen, they cause the molecules to emit light. By rapidly scanning these spots across the screen, the tube creates a complete, moving image.413