Refraction of Light Waves

Introduction

• Refraction occurs when waves change direction as they pass from one medium to another, such as from air into glass.
• Key topics:
  • Ray diagrams
  • Triangular prisms

Wave Speed and Medium Density

• Wave speed varies in different materials due to differences in medium density.
• Electromagnetic waves, like light, travel slower in denser materials.
  • Example: Wave slows down moving from air (less dense) to glass (more dense).
• If waves hit a boundary at an angle, they refract, changing direction.

Refraction Details

• Perpendicular Entry: Waves continue straight if traveling perpendicular to the boundary.
• Angular Entry: Waves hitting at an angle refract:
  • Entering denser medium (e.g., air to glass) bends towards the normal.
  • Normal: The dashed line perpendicular to the surface.

Ray Diagrams for Refraction

• Drawing Ray Diagrams
  1. Draw the normal perpendicular to the glass surface at the point of incidence.
  2. Indicate the path the ray would follow if it didn't refract.
  3. Draw the refracted ray bending towards the normal (in denser medium).
  4. Extend the refracted ray to the other side of the glass.
  5. Repeat the process as the ray exits the glass:
     • Exiting denser medium to less dense (glass to air) bends away from the normal.
  6. Label the angle of incidence and the angle of refraction.

Wave Speed Equation

• Equation: Wave speed = Frequency x Wavelength
• Upon refraction:
  • Frequency remains constant.
  • Wavelength changes:
    • Speed increase → Wavelength increase
    • Speed decrease → Wavelength decrease

Dispersion through a Triangular Prism

• Different wavelengths of light refract differently.
• White light through a prism disperses into a spectrum (rainbow effect).

Conclusion

• Understanding refraction involves considering wave speed, medium density, and ray diagrams.
• Dispersion demonstrates the refraction of different light wavelengths.