How does a tube light on its both side change its colour to black.?

how is the dark colour seen in the tube light whe we use it long time? to say oxidation it is impossible because there won't be oxygen inside . so what's the ansHow does a tube light on its both side change its colour to black.?
It's metal deposits from the electrodes.

The cathode and anode are on either ends of the tube.

They send eletrons to each other. The light is generated from the electrons in the tube bouncing off atoms in there.

To free the electrons from the metal cathode and anode, they are heated up. That allows the electrons to escape more easily.

But because they are hot, they evaporate a tiny bit of the metal they're made of.

That metal is deposited on the glass.

That is why the tube blackens on the ends (where the electrodes are) and not so much in the middle.



An incandescent lightbulb does the same :the filament heats up and metal from it is deposited on the glass. An old bulb is darker.How does a tube light on its both side change its colour to black.?
A cathode ray tube (CRT) is a type of analog display device. Cathode ray tubes are special, electronic vacuum tubes that use focused electron beams to display images. Though tubes of this type are used for many purposes, cathode ray tubes are most famous for their use in such things as televisions, oscilloscopes, computer and radar displays, and automated teller machines. Cathode ray tubes are also used in video game equipment.



A cathode ray tube has a cathode or negatively charged terminal. In a cathode ray tube, this terminal is a heated filament, much like the filament seen in a light bulb. The filament is contained inside a vacuum within a glass tube. Inside the tube, a beam of electrons is allowed to flow from the filament into the vacuum. The flow of the electrons is natural, not forced.



When used inside a television set, a CRT’s electrons are concentrated into a tight beam by a positively charged terminal, called an anode. An accelerating anode is then used to speed up the movement of the electrons. These fast-moving electrons fly through the tube’s vacuum, hitting the phosphor-coated screen and making it glow.



A German physicist named Karl Ferdinand Braun is credited with inventing the cathode ray tube in 1897. His invention consisted of a cathode ray tube with a fluorescent screen. This new technology was called a cathode ray oscilloscope. The screen of this tube would display a light when a beam of electrons touched it. Braun’s cathode ray oscilloscope is considered the predecessor of modern tubes used in television sets.



In 1929, Vladimir Kosma Zworykin created another type of cathode ray tube. Called the kinescope, this CRT was designed for used with some of the earliest televisions. Two years later, Allen B. Du Mont introduced the first cathode ray tube that was considered practical for use in a television set. It was also more durable than some of the previously introduced CRTs.



The cathode ray tube still plays a major part in television sets and many other electronic devices. However, there have been many new developments in display technology, such as plasma screens, liquid crystal display televisions (LCD TVs), and digital light processing (DLP) devices. Organic light-emitting diode (OLED) displays are also used to produce images. Still, the cathode ray tube maintains its popularity in television systems, as evidenced by the fact that the television is frequently referred to as “the tube.”

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