Neon tube lights, commonly known as neon lights, work based on the principle of gas discharge. Here's a step-by-step explanation of how they function:

1. Gas Filling:
   • Neon tubes are glass tubes that are initially evacuated to remove air and other impurities.
   • They are then filled with a low-pressure mixture of gases, primarily neon, but can also include other gases like argon, helium, or mercury vapor to produce different colors.
2. Electrode Placement:
   • At both ends of the tube, electrodes are positioned. These electrodes are connected to an electrical power source.
3. Voltage Application:
   • When a high voltage (typically between 1,000 and 15,000 volts) is applied to the electrodes, it creates an electric field inside the tube.
4. Electron Excitation:
   • The electric field accelerates electrons, which collide with the atoms of the gas inside the tube.
   • These collisions excite the electrons in the gas atoms, promoting them to higher energy levels.
5. Ionization and Plasma Formation:
   • As the electrons gain enough energy, they can be plucked out of the atoms, resulting in ionization.
   • The atoms left behind become positively charged ions, while the freed electrons become negatively charged.
   • This combination of positively and negatively charged particles creates a plasma, which carries the electric current between the electrodes.
6. Light Emission:
   • As the excited electrons return to their original energy levels, they emit photons (particles of light) in the form of visible light.
   • The color of the light emitted depends on the type of gas present in the tube. For instance, neon gas produces a red-orange light.
7. Voltage and Current Regulation:
   • The voltage and current supplied to the tube are carefully regulated to maintain a stable glow and prevent damage to the tube.
8. Color Variation:
   • By mixing different gases or using fluorescent coatings on the tube walls, a wide range of colors can be achieved.

In summary, neon tube lights work by exciting the electrons in the gas atoms through the application of a high voltage, resulting in ionization and the formation of a plasma that emits light when the electrons return to their original energy levels. The color of the light is determined by the type of gas present in the tube.