How is heat conducted?

Let us talk today about how heat conduction occur and why metals are good heat conductors. Heat is energy that can be transferred from hotter to colder body and can be quantified from temperature. But then obvious question is how does this energy transfer takes place? In this discussion, we will only focus on transfer of heat only via conduction and do not take into consideration radiation phenomenon. 

At microscopic level, we can quantify heat as motion of atoms. Hotter the body is, more kinetic energy the atoms have (they are shaking vigorously). Now, when you put a hotter body in contact with a colder body, atoms in hotter body which are moving vigorously start to shake the atoms of colder body in contact. This leads to transfer of kinetic energy (vibration of atoms in solids) from hotter body to colder body and thus transfer of heat. 

For metals, you also have electrons which are free, so both electrons and atoms will acquire kinetic energy. In fact, both electrons and atoms are responsible for transfer of heat in metals. In case of ceramics and dielectrics, only atoms are responsible for transfer of heat. In solid-state physics, a concept known as phonons is used to describe heat transfer process. Phonons is just a fancy word used to describe collective and in-sync motion of atoms. Because atoms are bound (bonding), you have synchronized motion of atoms. 

In next post, let us discuss the phenomenon of radiation which is another way to transfer heat.