Hõõgumine

Hõõgumine, often translated as incandescence or glowing, is the emission of light by a substance as a result of its being heated. This visible radiation is part of the electromagnetic spectrum and is produced when the temperature of an object is raised to a point where it begins to emit light. The color and intensity of the emitted light are directly related to the object's temperature. At lower temperatures, the emitted light may be in the infrared range, which is not visible to the human eye. As the temperature increases, the emitted light shifts towards the visible spectrum, starting with red, then orange, yellow, white, and eventually blue-white at very high temperatures.

This phenomenon is based on the principle of black-body radiation, where an idealized object absorbs all incident electromagnetic radiation and emits radiation based solely on its temperature. Real-world objects approximate black-body behavior. Common examples of hõõgumine include the glowing of a heated piece of metal, the filament in an incandescent light bulb, or the embers of a fire. The process is a fundamental concept in physics and has numerous practical applications, from lighting technology to pyrometry, which is the measurement of temperature using radiation. The intensity of the glow is proportional to the fourth power of the absolute temperature, meaning a small increase in temperature leads to a significant increase in emitted light.