Why rainbow is formed ? - Formation of Rainbow

 There are many theories about the formation of a rainbow. They all have to do with light being refracted and reflected in water droplets in the atmosphere.  The simplest explanation is given by the law of reflection. This law states that the angle of incidence is equal to the angle of reflection. The difference between the angle of incidence and the angle of refraction is what makes the rainbow.  

Most of the rainbow is seen at 42 degrees angle, the angle at which light is reflected from a water droplet in the atmosphere to our eyes.  The sun's rays are shining in all different directions but we see a rainbow because light reflects into our eyes from one particular angle.  The light that comes in at another angle is absorbed by water droplets and does not reach our eyes.