Thermal heat energy transfer is defined as the movement of heat from a hotter to a colder place----in other words, changing from a higher temperature to a lower temperature----and vice versa.
In this article, we will look closely at the ways in which thermal energy can be transferred.
We begin with conduction. How can we demonstrate this concept with objects you can find at home?
Place two spoons on a table----one metal and the other plastic. Pick up the metal spoon, which should feel relatively cold, and the plastic spoon, which should feel lukewarm or room temperature.
We can so say that the metal is a good conductor while the plastic a poor one.
When your finger touches a metal object heat is conducted out of your finger and into the metal, and this is because your finger gets colder.
On the other hand, as plastic is a good insulator, the heat can't travel further and your finger won't lose any more heat and remains warm.
In other words, the term conduction means the transfer of heat through matter by the movement of particles (an increase of kinetic energy) from a hotter place to a colder one. The material itself is not moving differently from convection.
Now we will move on to another term: convection.
HOW? You all know that hot air rises. When air is heated its density decreases (expands). Since it is less dense it will just move upwards. Take a hot air balloon if it can fly it must have a density that is less than that of the surrounding colder air, otherwise, it can't float.
In more simple words convection wants to underline that there is the tendency of hotter and less dense material to rise, while colder, denser material to sink which will result in the transfer of heat.
The last new term of the day is radiation.
HOW? You will agree that when it is dark you can see much further than during the day. In the daytime, the most distant object that you might see is the Sun (150 million kilometers away). At night you can see much further, to the distant star (20 million million kilometers away).
The light that reaches us from the Sun and stars travels to us through space in electromagnetic radiation. They travel as electromagnetic waves. The hotter the object the more infrared radiation it gives out.
And also for the last term, I will say to you a simple definition of it. Radiation is the type of energy that comes from a source and travels through empty space and may be able to enter different kinds of materials.
Giulia Zucchelli
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