* Refractive Index: Every medium has a refractive index, which is a measure of how much light bends when it enters that medium. Liquids have a higher refractive index than air.
* Speed of Light: The speed of light is highest in a vacuum (approximately 299,792,458 meters per second). In any other medium, the speed of light is lower. The higher the refractive index, the slower the light travels.
* Why the change? This change in speed is due to the interaction of light with the atoms and molecules of the medium. The light waves interact with the particles, causing them to slow down.
Example:
* Light travels slower in water than in air because water has a higher refractive index than air.
This change in speed is what causes light to bend when it passes from one medium to another, a phenomenon known as refraction.
