Mirrors and Lenses

• Ray – is an idealized model consisting of a thin beam of light that travels a straight line.
• Wave front – is an imaginary surface that represents points in the wave that vibrate in unison.
• Reflection

  • Occurs when light or any other waves bounces off an object
  • The Law of Reflection: “the angle that a reflected ray makes with a normal (perpendicular) to a surface (angle of reflection) is equal to the angle that the incident ray makes with the same normal line (angle of incidence)
• Regular reflection – if the reflecting surface is very smooth, like a mirror, light beams reflect off all points of the surface at the same angle.
• Diffuse reflection – if the reflecting surface is slightly rough, like wall, light beams will hit the surface and reflect at many different angles.
• Mirror - optical device, commonly made of glass, with a smooth, polished surface that forms images by the reflection of

  rays of lights.
• Plane Mirrors

  • It is a mirror with a flat surface
  • the image form is a virtual image
  • Virtual image – is an image through which light does not actually travel
• Concave Mirrors

  • It is a mirror that are curved inward
  • The image form depends on its optical axis (virtual image or real image)
  • Real image – is an image through which light passes
• Ray Diagram is a diagram that traces the path that light takes in order for a person to view a point on the image of an object.
• Center of Curvature - the point in the center of the sphere from which the mirror was sliced (twice the length of the focal point (F))
• Convex Mirrors

  • It is a mirror that curves out toward you
  • All images formed are virtual, upright, and smaller than the original object.
• Refraction – the change in the direction of light when it passes the interface of one media to another
• Willebrord Snell

  ◦ Dutch scientist

  ◦ Formulate the Snell’s law of refraction

  ◦ States that: “a ray of light bends in such a way that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant”
• Lenses - glass or other transparent substance so shaped that it will refract the light from any object and form a real or

  virtual image of the object.
• Convex Lenses

  ◦ Thicker in the middle than at the

  edges

  ◦ Light rays approaching the lens parallel to the optical axis are refracted toward the center of the lens

  ◦ Capable of producing many kinds of images, both virtual and real images, upright, inverted, enlarged, or smaller depending on the location of the object in relation to the focal length of the lens.
• Optical Phenomena

  • mirage
  • rainbow
  • halo
• Concave Lenses

  ◦ Thinner in the middle and thicker at the edges

  ◦ The rays passed are diverged and never form a real image