Light is one of those concepts in the subject of physics that we encounter irrespective of the class that we study in. Even in the middle classes we encounter some basic concepts about light and in the higher classes we encounter some advanced concepts about light.

In the middle classes of our education system we encounter light and in the higher classes we encounter the same concepts at the higher level. Even though, this chapter is one of the most difficult chapters in physics as it involves a lot of complications including equations, diagrams and loads of derivations. 

Light as electromagnetic induction 

Whenever we study about the concepts of light, the topic of electromagnetic induction should automatically come to our mind. One of the most talked about and famous controversies of physics is the fact that whether light is a wave or particle. Any conclusion regarding this has yet not been found. 

There have been many theories about the drawbacks and advantages of this concept but nothing has still not been confirmed. So if we are to write anything in this concept then it will always be filled with various arguments that have yet not been proven.

Reflection and Refraction 

The concepts of reflection and refraction are one of the most important concepts when we study light. These two concepts were known to be the basis and foundation of light and were so important that scientists felt the urge to write some laws of reflection and refraction. There are two laws of reflection and refraction each. 

If we consider another concept known as the Frensel Equations then we can say that there are three laws of reflection and if we are to state them in our own words then we can state that the first law of reflection states that the incident ray and the reflected ray are always present on the opposite side of normal. The second law of reflection states that the angle of incidence and the angle of reflection are equal and this is the most easy and direct law of reflection. The third law of reflection is the most important and the most difficult to understand and it states that the incident ray, reflected ray and the normal all lie on the same plane to the point of incidence. 

The same laws stand when we talk about the laws of refraction. The laws of refraction is one of those concepts in light that involves a lot of definitions and we have to completely understand these laws and statements if we are to memorize these formulas. The most basic law of refraction states that if we multiply the refractive index of one medium by the angle created in the water then it is equal to the refractive index of another medium and has to be multiplied by the angle created in another water.

Now the thing that has to be noted in these laws is the fact that these laws are completely independent of the mediums in which the refraction is taking place. Now the most important part of reflection is the part when we try to establish a relation between the refractive index and the wave speed, v. The relation that has been derived by various experiments and calculations is that the refractive index of the medium is equal to the division of the speed of light and the speed of wave, v. 

Particle and Wave Theory 

The particle theory and the wave theory are the two most important theories we have to discuss whenever the concept of light arises. These two theories are among those paradoxes which have still not been solved. Now, as the name suggests particle theory is that theory which states that light is made up of particles whereas wave theory is that theory which suggests that light is made up of waves. But in this article instead of talking about all this superficially, we will go into the depth of these two concepts. 

Now if we are to go into the depth of the wave theory, then there are many concepts such as diffraction which help to prove that this theory is true. Now diffraction is said to occur when there is a wave that is flowing through a distance and suddenly it reaches a point where it starts to up and down itself. Now this can only happen when the light is flowing like a wave and not like particles and this can be proved as if the light is flowing like particles then we know that the particles have the ability to scatter. As a result, the wave will also scatter which is not the ideal requirement. 

Now if we are to prove that the light is of the particle form then we have many physics related processes, but it would be good if we could start with some real life examples. For example, if we are studying on a table and we have a night lamp switched on or if we are sitting in a room and we have a tubelight switched on. The light could only reach the table or wherever we are because it was made of particles. If it was made of waves then this could not have been possible at all. Hence due to all these possibilities, examples and differences it can be said that these two theories cannot be solved yet.


The concept of light is one of the toughest, confusing and difficult to understand topics in the subject of physics. If we are to master this topic then we have to go through all the topics that have been taught to us before.