Here's a breakdown of how light behaves in a single medium:
1. Constant Speed:
* Within a uniform medium, light travels at a constant speed. This speed, denoted by 'c', is a fundamental constant, approximately 299,792,458 meters per second in a vacuum.
* However, the speed of light can change depending on the medium. Light travels slower in denser mediums like water or glass compared to a vacuum.
* The relationship between the speed of light in a vacuum (c) and the speed of light in a medium (v) is expressed through the refractive index (n): n = c/v. This means a higher refractive index implies a slower speed of light in the medium.
2. Bending of Light (Refraction):
* Light doesn't always travel in a straight line. When light passes from one medium to another (e.g., from air to water), it bends. This bending is called refraction.
* The amount of bending depends on the angle at which the light hits the boundary between the two mediums and the refractive indices of the two mediums.
* Snell's Law describes the relationship between the angle of incidence (the angle at which light hits the boundary), the angle of refraction (the angle at which light bends), and the refractive indices of the two mediums.
Illustrative Example:
Imagine a straw placed partially in a glass of water. When you look at the straw, it appears to be bent at the point where it enters the water. This is due to refraction. Light travels slower in water than in air, and as it passes from air to water, it changes direction, causing the straw to appear bent.
Key Points:
* The speed of light is constant within a single, uniform medium.
* The speed of light changes in different mediums.
* Light bends (refracts) when it passes from one medium to another.
* The amount of bending depends on the angle of incidence and the refractive indices of the mediums.
Understanding how light travels in a single medium is crucial for understanding many phenomena, including the working of lenses, prisms, and fiber optic cables.
