Different modes of Heat Transfer | Conduction, Convection, Radiation

TN-08-Science

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When you keep a metal plate near a burning wood, it becomes hot because of heat transfer. In this video, we will learn about different ways in which transfer of heat can take place.

Heat can be transferred from one object to other by conduction, or convection, or radiation.

When heat from one object gets transferred to other object by direct contact, it is known as conduction.

For example, when we make tea, heat from stove gets transferred to steel pan because of direct contact. and thus this is conduction.
When you iron your clothes, heat energy gets conducted from iron to clothes.

In convection method, movement of particles of liquid or gas cause transfer of heat from heat source.
Let's take an example of pot of water. As we heat it, water particles near the heat source gets heated first. We know that addition of heat causes increase in movement of particles thus these particles move randomly and a relatively empty space is formed. To fill this space, particles from far areas move here. Again these particles acquire heat energy and move away. This process goes on and whole water becomes hot.

In conduction and convection, there is a medium in which heat gets transferred. But there is no medium between sun and earth, still we get heat from it. This mode of heat transfer is called radiation. You must have seen people sitting around the fire, here too, heat is transferred in the form of radiation. In fact every hot body radiates heat and becomes cold.

Let's take an example of boiling water on a stove. From stove, heat conducts to pot as it is directly in contact. Due to convection, all the water particles receive heat. If you bring your hand very close to side of the pot, you will feel little hotness, this is because radiates coming from pot.