Thermal radiation refers to the electromagnetic radiation emitted by an object due to its temperature. All objects with a temperature above absolute zero (-273.15 degrees Celsius or 0 Kelvin) emit thermal radiation.
Differences between thermal radiation and regular electromagnetic waves, such as visible light, include:
Spectrum: Thermal radiation spans a wide range of wavelengths, from infrared to visible light to ultraviolet and beyond. The specific wavelengths emitted depend on the object's temperature. In contrast, visible light represents a specific range of wavelengths within the electromagnetic spectrum.
Intensity: The intensity of thermal radiation depends on the temperature of the object. As the temperature increases, the intensity of the thermal radiation also increases. In contrast, the intensity of visible light or other specific electromagnetic waves can vary independently of temperature.
Source: Thermal radiation is emitted by all objects with a temperature, whereas visible light and other electromagnetic waves are typically produced by specific processes, such as electron transitions in atoms or molecules.
Detecting thermal radiation can be achieved through various methods:
Infrared Cameras: Infrared (IR) cameras detect thermal radiation in the infrared region of the electromagnetic spectrum. These cameras utilize sensors that can detect and convert IR radiation into visible images or thermal maps. They are commonly used for thermal imaging in applications like building inspections, industrial monitoring, and even medical diagnostics.
Thermocouples and Thermistors: These devices measure temperature by utilizing the heat generated by thermal radiation. Thermocouples consist of two different metal wires joined at one end, while thermistors are temperature-sensitive resistors. By measuring the changes in electrical properties caused by thermal radiation, these devices can determine the temperature of an object.
Pyrometers: Pyrometers are non-contact devices that measure the temperature of an object by detecting its thermal radiation. They work based on the principle of comparing the intensity of the thermal radiation emitted by the object with a known reference source.
Bolometers: Bolometers are highly sensitive instruments used for detecting and measuring very weak thermal radiation. They are used in scientific research and applications that require precise measurements of low-intensity thermal radiation, such as astrophysics.
These are just a few examples of the methods used to detect and measure thermal radiation. Different techniques may be employed depending on the specific requirements and applications involved.