Introduction to Refraction

Light:
- A visible form of energy.
- A kind of electromagnetic wave, comparable to radio waves or x-rays.
- Produced when excited electrons in atoms jump to a higher energy orbital and subsequently return to their ground state.
- Can be modeled as rays that travel in straight lines from their source.
- Can undergo transmission, absorption, or reflection by different materials.
- Direction can be changed in predictable ways using mirrors as per the Law of Reflection.

Refraction: The bending of light when it travels from one material (medium) to another.
- Causes of Refraction:
- The speed of light alters when it enters a material with a different optical density.
- Changes in the speed of light can result in slowing down or speeding up as it transitions between materials that are more or less optically dense.

Fast Material vs. Slow Material:
- When light transitions from a fast material (e.g., air) to a slow material (e.g., water or glass):
- Light bends towards the normal (the imaginary line perpendicular to the surface at the point of incidence).
- Conversely, when moving from a slow material to a fast material:
- Light bends away from the normal.

Occurs when light strikes a material, resulting in:
- Some light being transmitted into the material.
- Some light being reflected back.
This interaction produces two rays:
- Reflected Ray: The ray of light that bounces off the surface.
- Refracted Ray: The ray of light that passes into the new medium.
Common Application: Two-way mirrors, which reflect some light while allowing other light to pass through.

Example: The design and functionality of a two-way mirror can raise questions regarding privacy and usability in practical applications, indicated by the inquiry: "Would you use this toilet?" with perspectives offered from both inside and outside.