The so-called cold light source is a light emitting light source that contains almost no infrared light spectrum , and is distinguished from a heat light source that contains an infrared spectrum . LED is a kind of cold light source , and the light he emits is almost all visible light . Visible light wavelengths from 380 to 780 nms . The traditional incandescent lamp is a heat source . Why does the LED heat sink up , because the power of the LED light source is only about 30% of the light energy , and that other energy is converted into heat energy , which is transmitted by heat conduction . So the LED lamps will be hot . The traditional incandescent lamp is only 2-3% of the electrical energy converted into light energy (visible light ) , and the rest is radiated from the form of infrared light . The characteristic of the cold light source is that almost all of the other energy is converted into visible light , the light of other wavelengths is small , and the heat source is different . In addition to visible light and a large amount of infrared light , a considerable part of the energy is converted into no contribution to lighting . Infrared light . So the so-called cold light source is actually not cold . Why do you say that LED cooling light source can save energy than incandescent lamp , in fact it means that its electric energy is converted into light energy with high efficiency . Therefore , lamp manufacturers must pay attention to heat dissipation when they are doing LED lamps , because if heat is not emitted , it will affect the luminous efficiency of the chip . So general LED lamps will have a radiator .