1. Speed of Light:
* Light travels at different speeds in different mediums. It travels fastest in a vacuum (like outer space) and slows down when it enters denser materials like water or glass.
2. Index of Refraction:
* The index of refraction (n) is a measure of how much light slows down in a particular medium. The higher the index of refraction, the slower the light travels.
* For example, the index of refraction of air is approximately 1, while water is about 1.33, and glass is around 1.5.
3. Snell's Law:
* Snell's Law describes the relationship between the angle of incidence (the angle at which light hits the surface), the angle of refraction (the angle at which it bends), and the indices of refraction of the two mediums.
* The formula is: n1 * sin(θ1) = n2 * sin(θ2)
* n1 = index of refraction of the first medium
* θ1 = angle of incidence
* n2 = index of refraction of the second medium
* θ2 = angle of refraction
4. Bending of Light:
* When light passes from one medium to another, it changes speed. This change in speed causes the light ray to bend.
* If the light is entering a denser medium (higher index of refraction), it bends towards the normal (an imaginary line perpendicular to the surface).
* If the light is entering a less dense medium (lower index of refraction), it bends away from the normal.
Example:
When light travels from air into water, it slows down. The light ray bends towards the normal because the index of refraction of water is higher than that of air. This is why a straw in a glass of water appears to be bent at the surface.
In Summary:
The change in the path of a light ray when it travels through different mediums is due to the change in the speed of light, which is determined by the index of refraction of the medium. This bending of light, called refraction, is described by Snell's Law.
