Hehkulämpö

Hehkulämpö, often translated as incandescence, refers to the emission of light by a substance that has been heated. This phenomenon is a result of thermal radiation, where the increased temperature of the object causes its atoms to vibrate more vigorously. These vibrations lead to the emission of electromagnetic radiation, a portion of which falls within the visible spectrum, making the object appear to glow.

The color of the emitted light is directly dependent on the temperature of the object. At lower temperatures, the radiation is primarily in the infrared spectrum, invisible to the human eye. As the temperature rises, the peak of the emitted radiation shifts towards shorter wavelengths, resulting in visible light. Initially, a dull red glow appears, which then progresses through orange, yellow, and eventually to white or even bluish-white at very high temperatures. This relationship between temperature and color is the basis for pyrometry, a method used to measure high temperatures by observing the color of incandescent objects.

Common examples of hehkulämpö include the filament of an incandescent light bulb, which glows white-hot when an electric current passes through it. Hot coals in a fire also exhibit incandescence, emitting a reddish-orange light. The surface of the sun, with its extremely high temperature, appears brightly white due to intense incandescence. Understanding hehkulämpö is fundamental in fields ranging from astronomy and materials science to lighting technology.