Question

Why does the light ray bend towards the normal when it goes from a rarer medium to denser medium?

Answer 1

When the refracted Ray enters the denser medium from the rarer medium,then it's speed gets reduced respectively. If it's speed gets reduced, then it will comapritively take more time to travel. However, as the refracted Ray takes the same time to travel, hence it takes a shorter path comapritively (through the denser medium) to travel and hence bends towards the normal.