CONVECTION!

Another process of thermal energy is convection.

convection is the transfer of thermal energy by means of currents in a fluid like liquids or gases.

Examples of convection in water:

convection in air: HOW DOES CONVECTION WORK?

Convection only occurs in fluids like liquids and gases but not in solids. This is because convection involves bulk movement of the fluids where the heat transported is by movement of heat particles. however for solids,thermal energy is transferred from one particle to another by vibration,without bulk movement.

Convection in water happens when water is heated,it expands. The expanded water will be less dense than its surroundings,and hence it will rise. The cooler parts of the water is now denser,and hence it starts to sink. Therefore,this will form a convection current.

Convection in air is similar. The hot air rises as it is less dense than the surrounding air. Hence,the cooler air being denser,will sink to take the place of the hot air. Hence,this will also form a convection current:D

For example, you can set up an experiment.

First,fill a beaker of water,then add a drop of coloured dye.

Put a bunsen burner under the beaker of water with the dye.

Slowly,you will be able to observe that the dye will slowly spread throughout the whole beaker of water.

This is because of convection. the water at the bottom of the beaker with the dye will get heated up first. Since it has lesser density now,it floats up,causing the cooler water to sink.

Hence,soon,the whole beaker of water will soon be filled with the dye:D

An example of convection is like the land and sea breeze.

In the day, the air on the land will tend to get hotter than the air in the sea. The hot air above the land will rise, and the cool air above the sea will sink to take the place of the hot air. Hence,that is known as a sea breeze.

At night, the air in the sea will tend to get hotter than the air on land. The hot air from the sea will rise,and the cool air on land will sink to take the place of the hot air. Hence,this is known as a land breeze.:D

Applications on convection[:

AIRCON

KETTLE

The heating coil of the kettle is always placed at the bottom because as the water in the kettle starts to boil, the water at the bottom of the kettle starts to heat up,resulting in te hot water to rise. The colder water sinks, so as the water around the heating element gets hot, it rises while it is heating, with the cold water taking its place.

FRIDGE

OVEN