Television pictures result due to fluorescence of cathode rays on the television screen.

Explanation:
Television pictures are produced by the emission of cathode rays from the cathode-ray tube (CRT) present in the television set. The cathode rays are a stream of fast-moving electrons that are generated by the cathode in the CRT. These electrons are accelerated towards the anode (screen) of the CRT, and when they hit the fluorescent screen, they cause it to emit light.

Fluorescence of Cathode Rays:
When the high-speed electrons strike the fluorescent screen, they transfer energy to the atoms or molecules present in the screen material. This energy excites the atoms or molecules, causing them to move to higher energy levels. As the excited atoms or molecules return to their lower energy levels, they release the excess energy in the form of light. This phenomenon is known as fluorescence.

Phosphors on the Television Screen:
The fluorescent screen of a television set is coated with a layer of phosphors. Phosphors are substances that exhibit fluorescence when excited by certain types of radiation, such as cathode rays. The phosphors used in television screens are typically compounds of zinc, cadmium, or other elements. These phosphors emit different colors of light when excited, allowing the television to produce a full-color image.

Pixel Formation:
The fluorescent screen on the television is divided into numerous small dots called pixels. Each pixel is coated with a different phosphor compound that emits a specific color of light when excited. By controlling the intensity and focus of the electron beam that strikes each pixel, the television can produce images with different colors and brightness levels.

Image Formation:
When the electron beam scans across the screen in a specific pattern, it excites the phosphors on the pixels, causing them to emit light. By varying the intensity and position of the electron beam, different pixels are excited at different times, creating a pattern of illuminated dots that forms the image on the television screen. This process happens rapidly, and the persistence of vision in our eyes combines these individual dots of light to form a cohesive image.

In conclusion, television pictures result from the fluorescence of cathode rays on the fluorescent screen. The high-speed electrons in the cathode rays excite the phosphors on the screen, causing them to emit light, which forms the images that we see on the television screen.