Convection

The transmission of heat from one part to another part due transfer of particles of matter is known
as convection.

Convection process is mainly identified in liquids. This process can be understood by taking the water in a beaker and few pieces of potassium permagnete is added to the water. On heating the beaker, it is found that the particles at the bottom get heated and the water at the bottom of the beaker becomes less dense so that the particles at bottom of the beaker comes upward, the particles at the upper region being dense flows down to reach the bottom of the beaker and in turn those particles get heated becomes less dense and againg these particles comes upwards. Like this, the water in the beaker gets heated due to convection process. How can recognise this process? For that purpose we added pottasium permagnete to the water. The movement of the particles of pottasium permagnete with water particles moves ups and down confirm the process of convection.

But convection process is quicker than conduction process.
Still air cooling in the closed room, ventilation cooling by the constant current of air flow into the room, through an open window,land and sea breezes are examples of heat transfer by convection.