Definition
Refraction of Light is the bending of light rays as they pass from one transparent medium to another with a different optical density.
Why It Matters
It is the physical basis for lenses, eyeglasses, cameras, and magnifying glasses.
Core Concepts
- Law of Reflection: Angle of incidence = Angle of reflection (measured from the normal).
- Refraction:
- Toward the Normal: Light slows down (entering a denser medium).
- Away from the Normal: Light speeds up (entering a less dense medium).
- Total Internal Reflection: Occurs when the angle of incidence exceeds the critical angle in a dense medium, causing the light to reflect entirely back into the medium.
- Dispersion: The separation of light into colors by frequency (e.g., a prism or a rainbow) because different frequencies travel at slightly different speeds in a medium.
- Virtual vs. Real Image:
- Virtual: Rays only appear to come from the image (e.g., a plane mirror).
- Real: Rays actually converge at the image location (e.g., on a camera sensor).