1. Speed Change: Light travels slower in water than it does in air. This is because water is denser than air, meaning there are more molecules packed together. The light waves have to interact with these molecules, slowing them down.
2. Bending: As the light ray enters the water, it slows down. The part of the wave that enters the water first slows down before the rest of the wave, causing the wavefront to bend.
3. Angle of Refraction: The amount of bending, or the angle of refraction, depends on the angle of incidence (the angle at which the light hits the surface) and the indices of refraction of the two media (air and water). The index of refraction is a measure of how much light slows down in a medium.
Here's a simple way to visualize it:
Imagine a car driving on a paved road and then suddenly entering a muddy field. The car will slow down and change its direction because it's encountering resistance from the mud. Similarly, the light ray slows down and changes direction when it enters the denser water.
Key Points:
* The light ray bends towards the normal (an imaginary line perpendicular to the surface) when it enters a denser medium.
* The angle of refraction is always smaller than the angle of incidence.
* If the light ray hits the surface at a 90-degree angle (perpendicular to the surface), it will not change direction.
This phenomenon of refraction is responsible for many interesting optical effects, such as:
* The apparent bending of a straw in a glass of water.
* The way a magnifying glass works.
* The formation of rainbows.
