* Speed of Light: Light travels faster in air than in water. This is because air is less dense than water, meaning there are fewer molecules for the light to interact with.
* Change in Direction: When a light ray enters water from air, it slows down. This change in speed causes the light ray to change direction, bending towards the normal (an imaginary line perpendicular to the surface of the water). The amount of bending depends on the angle of incidence (the angle at which the light ray hits the water surface) and the difference in the speed of light between the two mediums.
* Refractive Index: The refractive index of a material is a measure of how much light slows down when it enters that material. Water has a higher refractive index than air, meaning light travels slower in water. This difference in refractive index is what causes the bending of light at the boundary between the two mediums.
Here's an analogy:
Imagine you're walking on a sidewalk and suddenly step onto a patch of sand. The sand is like the water, and your walking speed slows down. You'll naturally change direction slightly as you move from the sidewalk (air) to the sand (water).
In summary, light bends when it travels from air to water because it slows down due to the difference in the speed of light in the two mediums. This change in speed causes the light ray to change direction.
