A refracted ray is the portion of a light ray (or other wave) that has changed direction after crossing the boundary between two different media.
Understanding Refracted Rays
Based on the provided definition, refracted rays can be defined as the part of rays that moves after deviation in the medium after ray incident on its boundary from a another medium. This phenomenon, known as refraction, occurs when a ray of light transitions from one transparent medium (such as air) into another with a different optical density (like water or glass). The change in medium causes the ray to change its speed, which in turn leads to the bending or deviation of its path.
Key Characteristics of a Refracted Ray:
- Deviation from Path: The most defining characteristic is that the ray has deviated—it has bent or changed its original straight-line path.
- New Medium: The refracted ray is found within the second medium after the light has crossed the interface between the two substances.
- Origin from Incident Ray: It is the result of an incident ray striking the boundary between the two media.
The Role of Incidence in Refraction
The process leading to a refracted ray begins with an incident ray interacting with a surface. Understanding this interaction is fundamental:
- Point of Incidence: This is the exact spot where the incident ray first makes contact with the boundary or surface separating the two different media.
- Normal Line: To describe the angles involved in refraction, an imaginary line called the "normal" is drawn. This line is always perpendicular (at a 90-degree angle) to the surface at the point of incidence.
- Angle of Incidence: As stated in the reference, "The angle formed between the normal and the incident ray at the point of incidence is called the angle of incidence." This angle is crucial, as it dictates how much the ray will refract, following principles like Snell's Law.
When Do Refracted Rays Occur?
Refraction, and consequently the formation of refracted rays, is a common optical phenomenon observed in various applications and natural occurrences:
- Lenses: The operation of eyeglasses, cameras, telescopes, and microscopes relies entirely on the precise refraction of light through lenses to form images.
- Prisms: When white light passes through a prism, it separates into its constituent colors (the spectrum) because each color refracts at a slightly different angle, a process called dispersion.
- Objects in Water: A classic example is a straw appearing bent when submerged in a glass of water, or a coin at the bottom of a pool seeming shallower than it actually is. This is due to light rays from the object refracting as they travel from water into the air.
- Atmospheric Phenomena: Mirages, the shimmering of air above hot surfaces, and the apparent flattening of the sun at the horizon are all examples of light refraction in the Earth's atmosphere.
Incident Ray vs. Refracted Ray
To clarify the distinction, consider the following comparison:
| Feature | Incident Ray | Refracted Ray |
|---|---|---|
| Location | Travels in the first medium, approaching the boundary | Travels in the second medium, after crossing the boundary |
| Path | Follows its original, straight path | Has a deviated or bent path |
| Origin | Comes from a light source | Is the continuation of the incident ray after interaction |
| Angle Reference | Forms the angle of incidence with the normal | Forms the angle of refraction with the normal (which determines its new direction) |
