Question

As far as we know, water is transparent but when you drop water in front of a wall or something, you can see the water's shadow. How's that possible?​

Answer 1

Explanation:

Glass and water are thicker and heavier than air. They are said to be 'denser' than air. What happens is that light slows down when it passes from the less dense air into the denser glass or water. This slowing down of the ray of light also causes the ray of light to change direction.