Radiators are devices used for heating spaces by transferring heat through convection. They work by circulating hot water or steam through pipes within the radiator unit. As the liquid or steam heats the radiator, the surrounding air is warmed, providing heat to the room through convection and radiation.
Chapter 10 of Class 11 Physics focuses on thermal properties of matter. It deals with concepts like temperature expansion and heat transfer. The chapter explores different types of expansion such as linear superficial and cubical expansion. It also covers heat conduction convection and radiation with practical applications in daily life and industrial uses.
Prevost’s Theory of Heat Exchange :
Prevost’s theory of heat exchange is that all bodies emit continuous thermal radiation; it doesn’t matter what the temperature is or what their surroundings are. Emission depends on a body’s nature and temperature, not whether or not there are other bodies around. In contrast to the emission, bodies absorb radiation from their surroundings.
Heat exchange happens between two bodies because of the difference in temperatures of those bodies. The hotter body radiates more energy than it absorbs, whereas the cooler body absorbs more energy than it radiates. This means that there is a net transfer of heat from the hotter body towards the cooler. When a body is in thermal equilibrium with the surroundings, it radiates as well as absorbs energy at the same rate. In this case, there is no net transfer of heat. This process is dynamic, as radiation as well as absorption is in continuous motion. Good Absorbers are Good Radiators :
By Prevost’s theory, a good absorber is also a good radiator.
This is because the properties that enable a surface to absorb energy efficiently allow it also to emit energy efficiently. For instance, black surfaces, which are excellent absorbers of radiation, are also excellent radiators. The relationship is quantified by Kirchhoff’s Law, which asserts that the emissive power of a body is proportional to its absorptive power at the same temperature and wavelength.
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