According to particle theory of light if a light ray bends toward the normal while entering from medium 1 to medium 2 then how the velocity of light in medium 2 is greater than the velocity of light in medium 1 ?
When a medium enters a denser medium from a rarer medium, it bends towards the normal. This is the observation we have in hand and this phenomenon is called refraction.
Sir Isaac Newton tried to explain the phenomenon of refraction using his particle theory. He said that the particles of the denser medium attracts the particles with stronger force towards it which makes it bend towards the normal.
If there is such a force of attraction, then the speed of light would increase inside a denser medium. When the velocity of light in different media was determined by Foucault and other scientists, it was found that the velocity of light in denser medium is less than that in a rarer medium. So, Newton’s explanation of refraction was proved wrong.