Infrared, heat radiation, and light are related but differ in terms of their wavelengths and the ways they interact with matter.
Light: Light refers to the range of electromagnetic radiation that is visible to the human eye. It spans a relatively small portion of the electromagnetic spectrum, with wavelengths ranging from approximately 400 to 700 nanometers. Light can be further divided into different colors based on its wavelength, from shorter violet and blue wavelengths to longer yellow, orange, and red wavelengths. Light interacts with matter in various ways, including reflection, refraction, and absorption, and it is responsible for our visual perception.
Infrared (IR): Infrared radiation refers to electromagnetic waves with longer wavelengths than those of visible light. It falls on the electromagnetic spectrum between microwaves and visible light, with wavelengths ranging from about 700 nanometers to 1 millimeter. Infrared radiation is invisible to the human eye, but it can be detected and measured using specialized devices such as infrared cameras or sensors. Infrared radiation is commonly associated with heat because many objects emit infrared radiation as a result of their temperature. However, not all infrared radiation is related to heat, as it can also be produced by electronic devices or other sources unrelated to temperature.
Heat Radiation: Heat radiation, often referred to as thermal radiation, is a form of energy transfer that occurs due to the temperature difference between two objects. It involves the emission and absorption of electromagnetic waves, including infrared radiation. When an object is heated, it emits heat radiation in the form of electromagnetic waves, including infrared waves, which carry thermal energy. The intensity and spectrum of heat radiation depend on the temperature of the object. The hotter an object, the greater the intensity of the heat radiation it emits. Heat radiation can be felt as warmth or experienced as the transfer of heat from one object to another.
In summary, light refers to visible electromagnetic radiation, while infrared radiation encompasses longer wavelengths that are beyond the range of human vision. Heat radiation is a form of energy transfer that includes the emission and absorption of electromagnetic waves, including infrared radiation. While light and infrared radiation are part of the electromagnetic spectrum, heat radiation refers specifically to the transfer of thermal energy through electromagnetic waves, including infrared.