6. Electromagnetic force or Light

Welcome back..

In this post, we are going to explore what the physics behind light or electromagnetic force is. In previous posts, we had seen how the strong force formed the nucleus and how the weak force formed the atoms. Now, what is next? No doubt.. Molecules!

Molecules are the reasons for matter to gain certain form in this universe. Atoms are combined together to form a molecule. In order for atoms to get together, we need a force that can operate between atoms. Such force is called intermolecular force. When we are talking about atoms and molecules formation, our interest is mainly on the electric form of the electromagnetism or the electric fields. We will keep the magnetic fields aside for now.

So, let's see how electric fields help in the formation of molecules. In fact, without electromagnetic force, even protons and electrons will not have charges and even atom might not have been formed! Though we had seen that strong & weak forces form atoms, without electric charges or fields, it's impossible for atomic nuclei to hold the electrons surrounding them.

What do atoms have to do to mingle with each other? Electromagnetism is the force that results when charged particles exchange photons. As we all know that atoms have electrons readily available. These electrons are negatively (e-) charged. Now, when two atoms comes closer, there are several actions happen. I have listed them out below for better understanding.

1. The protons from both atomic nuclei repel each other due to same charge.
2. The electrons, which stays at the entrance of one atom, easily get attracted by the protons inside the other nucleus.
(Attraction/Repelling are resulted from the exchange of photons, the electromagnetic force!)
3. Since electrons cover the most of the area in an atom, it keeps the protons far apart from each other.
4. At the same time, electrons, which are more in count compared to proton and neutron, move closer to the protons (nucleus) from other atom
5. Since the attractive force overwhelms the repulsive force, due to sharing and transfer of electrons, a bond is formed between those two atom.

Such a bond is called a 'Chemical bond'. Similarly more chemical bonds are formed to create bigger molecules and eventually matter gets its form. This is the basic for H2O, O2, CO2, N2, SiO2, etc.. I mean all the fundamental molecules are formed due to this electromagnetic force. Quantum physics went one step further and explain what makes electromagnetic force to attract or repel the opposite or same charged particles respectively. Let's explore them in my next post.