Speed of light

[Vishnu Jadhav]

hi freinds

I have question

when ligth passes from air to glass what happens at particle level which force is responsible for rduce speed & to turn light ray. after escaping from glass speed of Light ray will increase or not if yes wihich force responsible for

while traveling through glass why not - speed constant & mass reduce

when we throw stone in water at the entry point weight (mass) of stone reduce because of density of water.

what is the nature of time space in densr medium