Heat transmission
From ArticleWorld
Heat transmission is a process by which heat flows from a region of higher temperature to region of lower temperature. This may take place via one or more media of transmission. There can be three possible ways of heat transmission: conduction, radiation and convection.
Heat is a form of energy that is said to be in transit, that is, constantly flowing in order to stabilize the temperatures in the surrounding. It raises the temperature of the substance which is at a lower temperature and lowers the temperature of the substance which is at a higher temperature. Heat can flow from a lower to a higher temperature only if active work is involved in the heat transfer.
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Methods of heat tranmissionr
Conduction
Conduction is a form of heat transfer between bodies or within a body. Such a form of heat transmission requires physical contact between bodies or portions of bodies exchanging heat. Heat energy is transferred across molecules having higher energy to those with lower energy in order to bring about equilibrium. Such a form of heat transmission can be observed in a metal spoon being heated at the handle after being dipped in a bowl of hot water.
Radiation
The phenomenon of radiation does not require contact or the presence of any matter between the bodies involved in heat exchange. Heat is transmitted by infrared radiation, which is part of the electromagnetic spectrum. The heat from the sun is transmitted to the Earth and other planets in this manner.
Convection
Heat transmission by convection takes place by virtue of the motion of molecules of a gas or a liquid. This happens when the liquid or gas is in contact with a solid body which is at a lower or a higher temperature. Such a form of heat transmission is seen in centrally cooled rooms.