Devender

We have already discussed in the previous post that a hotter object has atoms with high kinetic energy. If this object is put in contact with a colder object, energetic atoms will start to transfer heat to atoms of colder object and this is phenomenon is known as heat conduction. But,  Sun is about 100 million miles away from the earth and yet we still feel it's heat. Space between earth and sun is vacuum  with no particles to conduct the heat. So, how is heat conducted 100 million miles away to earth without any heat carriers? This occur through the phenomenon known as "heat radiation".  Sun surface is very hot (about 6000 C) and so atoms of gases (hydrogen and helium) in Sun have very high kinetic energy. Electromagnetic radiation (heat) is emitted whenever an electric charge is accelerated.  These energetic atoms have positive charge and negative charge, and constantly bumping into other atoms and thus accelerating and decelerating. So, Sun emits heat in the form of

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 atom