Question

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What is convention ?
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Answer 1

heya ... good evening..
here is ur answer ..

the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat..

this can be seen in some microwave...

Answer 2

$\huge\bold\red{Question}$

What is convention ?

$\huge\bold\green{Answer}$

The exchange of heat by the actual movement of molecules is known as convection. It usually takes place in liquids.