Ch 1 light and sight


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Ch 1 light and sight

  1. 1. Light and Sight
  2. 2. 1.Source of light • Luminous object: object that give out light as the result of the excited atoms receive energy. • Non luminous object: Object that not send out light. • Laser: A type of light source in which their excited atoms act together and emit a narrow light.
  3. 3. 2.Rays and beams • Rays travel in straight lines • The path in which light pass= rays • A beam is a stream of light. • Beam of light can be parallel, converging, diverging.
  4. 4. 3.Shadows • Opaque: Object that doesn’t let light pass • Small source of light give sharp shadows with dark color all over. • Large large amount of light give a shadows with a pitch dark on the centre with gray area surrounds it. • Umbra: Dark region • Penumbra: Gray area
  5. 5. 4.Speed of Light • Very fast • Faster than sound
  6. 6. 5.Law of reflection • Normal : an imaginary line that perpendicular 90 degree to the surface. • Law of reflection : The angle of incidence equals angle of reflection.
  7. 7. 6.Periscope • Instrument that use 2 mirrors.
  8. 8. 7.Regular and diffuse reflection • Regular reflection is on a smooth surface. • Diffuse reflection is on rough surface. • Diffuse reflection does not follow law of reflection.
  9. 9. 8. Real image and Virtual image • Real image is the image that can be from on screen and produced by light rays that passed through it. • Virtual image is the image that cannot be produced on screen and produced by rays that seemed to pass through it but not.
  10. 10. 9. Lateral inversion • This is an effect produced by plane mirror. • Your left and right eyes are interchanged. • Occurs whenever an image is formed by one reflection.
  11. 11. 10. Properties of plane mirror • As far behind the mirror as the object is in front and the line joining the object and image is perpendicular to the mirror. • The same size as the object. • Virtual • Laterally inverted
  12. 12. 11. Kaleidoscope • A set of two mirror set at an angle to produce multiple image. • Formula to find the image produce by two mirrors forming specific angle: 360 X - 1
  13. 13. 12. Facts about reflection • Light ray that enter a denser medium have angle of reflection smaller than angle of incidence. • A light ray is bent away from the normal when enter a less dense medium. • A light ray is bent towards the normal if it enters a denser medium. • A ray emerging from parallel sided block is parallel from ray that enter the block. • A ray enter at the normal of an object is not refracted.
  14. 14. 13. Refraction index • Refraction happens because change of speed of light. • Reactive index = Speed of light in air or 1st medium Speed of light in 2nd medium
  15. 15. 14.dispersion • The spread out of color spectrum when white color light pass through a prism.
  16. 16. 15.Critical angle • The angle at which the angle of refraction is 90 degree. • When the light does not pass the boundary it is said that it undergo total internal reflection.
  17. 17. 16.Multiple images • It happened because of the multiple reflection inside a glass of mirror which cause blurring.
  18. 18. 17.Total reflecting prisms • The prism which completely reflecting light rays.