1 Any object with a temperature higher than the absolute temperature will produce "thermal radiation", and the wavelength of radiation can range from infrared to visible light. It is the basic principle of infrared scanning imaging to obtain the visible light image of the detected object by using the difference of infrared thermal radiation between the detected object and the background object.

The thermal radiation of an object makes it lose its own energy. The stronger the radiation ability, the faster the loss. Put two cups of hot water with the same temperature and quality, one in the covered refrigerator (to reduce convection) and the other in the freezer. Obviously, the temperature of cups with high ambient temperature drops slowly, which may mean that their heat dissipation speed is different.

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