Why Does Black Absorb Heat?
Black as a color absorbs heat because of specific properties of the color and of the light. When light shines on an object, the object’s color either absorbs or reflects the light. A red object, for example, absorbs every color except for red, which reflects back to the eyes. The color of the object depends on the light radiated back to the eyes. If that same red object, like a red apple, were to be illuminated by a light source that had no red wavelength, it would appear almost black, because there would be no wavelength of light to reflect back to the eyes. ‘White, light actually has all of the wavelengths in it, which causes the multitude of colors in life.
When white light hits a black object, the object absorbs all of the wavelengths, and none are reflected back, which is why the object appears black in the first place. Now you can think of light as energy in almost all situations: for example, all of the energy that you get comes from the ability of plants to absorb that light energy and store it in sugars. When you eat meat, the animal that you are eating had to get its energy from plants (at the very bottom of the food chain) as well. So when black absorbs the light, it is also absorbing energy. The object then radiates the energy by emitting it at a longer wavelength that is invisible to the eye, but is still energy. It is emitted at the infrared level, which is heat. The key to understanding the transformation of light into heat is that it conserves all energy ‘š one of the laws of thermodynamics, or the study of energy conversion between heat and mechanical work. No heat is lost; it is just transformed into a new form, a new wavelength.