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Convection In Liquids And Gases:

Liquids and gases are generally poor conductors, Heat is eventually transferred in them by convection.

Convection is a process by which heat is transferred in a liquid or gas by actual movement of the heated fluid from the hotter to the colder parts.

Example: Convection current in a kettle when boiling water in the kettle, when the water is heated below, its molecules near the heat source gain more kinetic energy.

The heated molecules vibrate farther away from their fixed position and become less densely, the rise from the bottom to the top carrying thermal energy along with them. The denser molecules from the top sink to the place of those that haven risen above. Those molecules in turn get heated and rise, thus setting up acrylic motion of liquid molecules until the water boil.

Application Of Convection

> House ventilation and in moving smoke up the chimney.

> Radiation cooling system, by incoming air flowing round the engine and in engine cooling system.

Convection Current In Nature

Land and Sea breeze

Land and sea breezes are the result of convection current in Nature. In a hot day, the sun warms the land more quickly than the sea, because land is a better absorber of heat and also has a lower specific heat capacity. As a result of this the air near the land warms up and rises cooler .

The convection current is completed by air in the upper atmosphere moving down in the opposite. The cool breeze that blows in land from the sea is known as a Sea Breeze.

At night, the sea retains much of its heat while the land temperature drops considerately as a result convection current is set up in the opposite direction to the day time.

The breeze moving from the land to the sea is known as Land Breeze.

Submitted by: Floxy

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