REFRACTION OF LIGHT

• What is Refraction?


  It is the bending of a wave when it passes from one medium to another.
• What causes Refraction?

  When light goes from one medium to another, the velocity and path changes.
• Laws of Refraction


  The first law states that..

  • The incident ray, refracted ray, and the normal lie on one plane
• The second law states that...


  (a.) When light passes obliquely from an optically denser medium to a less dense medium, it is refracted away from the normal

  • Denser > Less Denser = away
  • Angle of Incidence is lesser than the angle of refraction
• The second law states that..

  (b.) When light passes obliquely from an optically less dense medium to a denser medium, it is refracted towards the normal.

  • Less Denser > denser = towards
  • Angle of incidence is greater than the angle of refraction
• The second law states that..

  (c.) When the incident ray is perpendicular to the interface, no bending of light occurs.
• What is Index of Refraction or Refractive index? 


  It is the measure of the bending of a light ray when it passes from one medium to another.

  • It can also be defined as the ratio of the speed of light in vacuum to that in the substance
  • n=c/v
• Refractive index (n) is always greater than 1 because v is always smaller than c.
• n=c/v

  • n = Index of Refraction
  • c = Speed of light in a Vacuum
  • v = Speed of light in a Medium
• Snell's Law

  
• 
  

  n1 = Index of Refraction of the incident medium

  n2 = Index of Refraction of the refractive medium

  O1 = Angle of Incidence

  O2 = Angle of Refraction

  
• What is the Index of Refraction of Air?


  1.0003
• If mirrors produce images by reflection, lenses produce images by refraction
• Convex Lenses


  It is thicker in the middle and converge light rays into a real focus or focal point

  • Also called Converging Lenses
• Concave Lenses


  Thinner in the middle but thick in the edges. It diverges light rays into a virtual focus

  • Also called Diverging Lenses
• What are the two types of Convex and Concave Lenses?

  • Double
  • Plane
• How many Principal Rays does lenses have?

  Three
• What are the three Principal Rays of Lenses?

  • P-F ray
  • F-P ray
  • V ray
• Terms:

  • 2F = The point on the principal axis that is twice the the distance from the lens as the focus
  • F = Focal/focus point, the point where the refracted rays from parallel light rays converge or seem to diverge
  • F' = Focus prime
  • 2F' = 2F prime
• What is the LOST of Convex Lens when the object is at Infinity?

  A very tiny image that cannot be seen is formed.
• What is the LOST of Convex Lens when the object is beyond 2F'

  • L: between F and 2F
  • O: inverted
  • S: reduced
  • T: real
• What is the LOST of Convex Lens when the object is at 2F'

  • L: located at 2F
  • O: inverted
  • S: same size as the object
  • T: real
• What is the LOST of Convex Lens when the object is between 2F' and F'

  • L: beyond 2F
  • O: inverted
  • S: magnified
  • T: real
• What is the LOST of Convex Lens when the object is at F'

  No image is formed as rays refract parallel
• What is the LOST of Convex Lens when the object is within focal length

  • L: same side as the object
  • O: upright
  • S: magnified
  • T: Virtual
• What is the LOST of Concave Lenses

  • L: same side as the object
  • O: upright
  • S: reduced
  • T: Virtual