How do all kinds of lights shine, from firelight to incandescent lamp to LED?

Since humans learned to drill wood for fire, lighting has gone through the process from firewood, oil to electricity as energy. Lighting tools have undergone numerous changes, from torches, animal oil, vegetable oil, candles, kerosene lamps, incandescent lamps, fluorescent lamps, to various decorative lamps and LED lamps. Modern lighting has also developed from simple living lighting application to various fields, which has brought us great convenience in life and colorful visual experience.

From primitive times to ancient times, people mainly used flame as the main way of lighting at night, and changed from firewood to vegetable oil as fuel, but the essence of lighting has never changed. So why can flame bring light?

We know that combustion is a violent chemical reaction, and a lot of energy will be released during the reaction. Chemical reactions include the breaking of chemical bonds and the absorption of energy. Chemical bonds are formed and energy is released. The latter is higher than the former, so this reaction will produce a lot of energy, and the excess energy will be absorbed by electrons. The outer part of the nucleus consists of many electron layers. When electrons absorb energy, they will jump from low-level orbits to high-level orbits. Electrons in high-energy orbits are extremely unstable, so it is easy to jump back to low-energy orbits and release energy in the form of photons, which are high enough that their frequencies are within the frequency range of visible light we can see (of course, some of them are not within this range). This is the fire we saw.

Before the electric light appeared, kerosene lamps or gas lamps were widely used as lighting tools. Because this kind of lamp burns kerosene or gas, the black smoke is very thick, the smell is pungent, and it is inconvenient to add fuel, so the lampshade is often scrubbed. More importantly, this kind of lamp is easy to cause fire, which will lead to great disaster. For many years, many scientists have tried their best to invent a safe and convenient electric light.

Energy-saving lamps, as the name implies, are more energy-saving and have higher light efficiency. So why is energy consumption lower than incandescent lamps? Because the luminous mechanism of energy-saving lamps is completely different from that of incandescent lamps, let me introduce the luminous mechanism of incandescent lamps:

Different from the working principle of ordinary incandescent lamps, energy-saving lamps mainly heat filaments through ballasts.