The working principle of incandescent lamps is that heat is generated when the current passes through the filament (tungsten wire, melting point is more than 3,000 degrees Celsius). The spiral filament continuously collects heat, so that the temperature of the filament reaches 2000 degrees Celsius or more. When the filament is in an incandescent state, it is like The red iron can shine like the light. The higher the temperature of the filament, the brighter the light emitted. Therefore, it is called an incandescent lamp. When an incandescent lamp illuminates, a large amount of electrical energy is converted into heat, and only a small fraction (possibly less than 5%) can be converted into useful light energy.

 

Fluorescent lamps, also known as fluorescent lamps, work on the principle that a fluorescent tube is simply a closed gas discharge tube. The main gas in the tube is argon gas (including 氖neon or 氪krypton) and the gas pressure is about 0.3% of the atmosphere. Also contains a few drops of mercury - forming a trace of mercury vapor. Mercury atoms account for about a thousandth of all gas atoms. The fluorescent tube is a mercury atom that is placed against the tube, and the ultraviolet light is emitted by the process of gas discharge (the main wavelength is 2537 angstroms = 2537 x 10-10 m). About 60% of the energy consumed can be converted to ultraviolet light. Other energy is converted to heat.

 

The fluorescent lamp emits visible light by absorbing ultraviolet light from the fluorescent material on the inner surface of the tube. Different phosphors emit different visible light. Generally, the efficiency of converting ultraviolet light into visible light is about 40%. Therefore, the efficiency of the fluorescent lamp is about 60% x 40% = 24% - about twice that of the same power tungsten wire.

 

The energy-saving lamp is also called compact fluorescent lamp (referred to as CFL lamp in foreign countries), which has high luminous efficiency (5 times that of ordinary light bulb), obvious energy saving effect, long service life (eight times that of ordinary light bulb), small size and convenient use. It works in much the same way as fluorescent lamps. Generally, under the same wattage, an energy-saving lamp is 80% more energy efficient than an incandescent lamp, with an average life expectancy of 8 times and a thermal radiation of only 20%.

 

LED lights, also known as light-emitting diodes, are solid-state semiconductor devices that convert electricity directly into light. LED lamps have many advantages such as small size, low power consumption, long life, non-toxic and environmental protection, etc. LED lamps are gradually developed from outdoor decoration and engineering lighting to home lighting.