In the past, when we used incandescent lamps, we only knew how many watts of light bulbs we used. The bigger the wattage, the brighter it was. this is correct. However, the wattage of a lamp actually only represents how much power it consumes, and does not mean how much light it emits. This problem has become more and more important with the emergence of different types of luminaires. The appearance of fluorescent lamps has caused problems. The earliest fluorescent lamps used are the so-called fluorescent lamps. Fortunately, the most common fluorescent lamp is just a 1.2m T8 tube. So everyone doesn't know how many watts it consumes. It only knows that it saves electricity compared to ordinary incandescent lamps. In fact, the power consumption of this most common fluorescent lamp depends on what kind of ballast is used. The lamp itself is 36 watts. If a domestically used magnetic ballast is used, it usually adds 10W of power, so the power consumption of the whole lamp is 46 watts. The average user may not know. After the emergence of "energy-saving lamps", new situations have emerged. In fact, the so-called energy-saving lamps are just a kind of curved fluorescent lamps. It is called energy-saving lamps just to beautify them with the new term "energy saving". The most commonly used energy-saving lamp is 8W, which is equivalent to a 40-watt incandescent lamp. But the biggest drawback of energy-saving lamps is that they contain mercury, each of which can contaminate 180 tons of water and soil. However, the state has made every effort to promote "energy-saving lamps". In Shanghai, even every household is sent by the state for a white use (I don't know if there are big companies driving behind it). Since the country was promoted to the end of 2012, there are already hundreds of millions. Only energy-saving lamps have been scrapped, and 18 billion tons of water and soil have been polluted, and this pollution cannot be removed. It is no wonder that online rumors that Chinese immigrants went to the United States to check their bodies and found that the body's mercury content exceeded 100 times, which is not surprising. I. LED Bulb LED is a kind of lamp that does not contain mercury and has much higher luminous efficiency than the â€œenergy-saving lampâ€. It is the real energy-saving lamp. It is bound to become the mainstream product of lighting fixtures. Moreover, it has appeared in various shapes of lamps, including bulbs that can replace incandescent lamps, LED lamps that replace fluorescent lamps, LED ceiling lamps, LED downlights, LED PAR lamps, and so on. In order to save energy, countries have set a time limit for the production and sale of incandescent lamps. â€¢ Australia: 2010 â€¢ EU, Taiwan, Canada: 2012 â€¢ Korea: 2013 â€¢ Japan: 2012 (high energy) â€¢ USA: 2014 total ban â€¢ China: 2016 is completely banned, import and sales are prohibited in 2014, 10, 1 Incandescent lamps above 60 watts It is estimated that in 2014, due to the ban on incandescent lamps in many countries such as the United States, the global demand for LED bulbs increased by 86%. So we will focus on LED bulbs used to replace incandescent lamps. In order to make the user easy to accept, the LED bulb is specially made to resemble the shape and size of the incandescent lamp, and the lamp cap is exactly the same for easy replacement. At present, a large number of wattages consumed by LEDs in China are used as their main indicators. This formed a big loophole. Some low-efficiency bulbs shot an indicator of 1 yuan per watt, while slightly better bulbs produced an indicator of 2 yuan per watt. This is a very unscientific price/performance indicator. Because some low-efficiency bulbs consume a lot of power but don't produce a lot of light, but they are also called large wattages. It sounds like a good bulb, but it is actually a shoddy product. The correct indicator should be its luminous efficiency. This is a question to be discussed in detail in this article.