Why does a light ray bend -towards- the normal when passing from an optically rarer to a denser medium? Why not away from the normal?

Dear Student ,
When a light ray travels from one medium to another ,its speed changes. Speed of light decreases when it travels from rarer to denser medium. Therefore it bends towards normal.
Let us assume a ray of light passes from a medium with refractive index of n1, and then, it passes through a medium of refractive index n2. According to your question, n2 >n1. Keeping that in mind, let us take into consideration the Snell's law. It says,  Sin i/Sin r = n2/n1 = constant  So, we know that n2/n1> 1, implying that Sin i/Sin r >1.  This, then lead us to the fact that Sin i >Sin r, implying that i >r. Hence light bends towards normal not away from the normal .
Regards

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