Reflection and Refraction of Light

• The angle between the incident ray, normal line, and refracted ray is called the angle of incidence.
• Reflection: bouncing of light waves from a reflecting surface
• Two kinds of reflection:

  • Specular
  • Diffuse
• Specular Reflection: occurs when the reflective surface is smooth
• Diffuse Reflection: occurs when the reflective surface is rough
• Diffusion: dispersal of reflected light
• Absorption: transfer of energy carried by the light waves to the particles of matter
• Scattering: reflection of light by particles
• Although diffused light gives us irregular images, this phenomenon is also beneficial as it allows us to regulate the amount of light.
• The law of reflection is strictly observed when the reflecting surface is smooth. It is applicable to plane mirrors and spherical surfaces.
• Total Internal Reflection: occurs when the angle of incidence is greater than the critical angle.
• Laws of reflection:

  • the angle of incidence is equal to the angle of reflection
  • the incident ray, the normal to the mirror at the point of incidence, and the reflected ray all lie in the same plane
• Refraction: the bending of light as it passes from a medium
• Dispersion: separation of light into colors by a prism. This leads to effects such as chromatic aberration in lenses.
• In a prism, red light is bent the least while violet was bent the most.
• As light refracts, the velocity of the wave is altered, its wavelength increases or decreases, but its frequency remains constant
• The speed of light in a vacuum is denoted by c for constant or the Latin celeritas (swiftness)
• The speed of light in a vacuum is denoted a 3 x 10^8
• The index of refraction can be computed by: n = c/v
• As an incident ray passes through different media, the resulting ray bends. This creates the angle of incidence and angle of refraction.
• The rays forming the angle of incidence and angle of refractions occur in different planes.
• The angle of refraction increases as the angle of incidence increases.
• Critical Angle: when the angle of incidence produces an angle of refraction equal to 90 degrees
• Total Internal Reflection: phenomenon wherein the incident rays striking the boundary of two media are reflected back into the first medium and the bounding surface acts like a perfect reflector.
• Law of refraction:

  • The incident ray, the refracted ray, and the normal to the interface of two transparent media at the point of incidence all lie in the same plane
  • The ratio of the sine of angle of incidence to the sine of the angle of refraction is a constant for the light of a given color and for the given pair of media