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Optics: lenses, mirrors, and electromagnetic spectrum Physics


May 16, 2015




important facts about Optics, mirrors, light
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  • 1. Optics: lenses, mirrors, and electromagnetic spectrum Physics

2. Properties of Light

  • Light travels in straight lines
  • Light travels much faster than sound
  • We see things because they reflect light into our eyes
  • Shadows are formed when light is blocked by an object


  • Luminous and non-luminous objects

Aluminousobject is one that produces light. Anon-luminousobject is one that reflects light. 4. Visible spectrum 5. Visible Eac h co lor is a differe nt si ze w ave . Red the longest &violet the shortest

  • Emitted by
    • The sun and other astronomical objects
    • Laser pointers
    • Light bulbs
  • Detected by
    • Cameras
    • (film or digital)
    • Human eyes
    • Plants (red light)
    • Telescopes

RoyG.Biv 6. What are sun rays?

  • The sun emits several kinds of electromagnetic radiation: Visible (Vis), Infrared (IR) and Ultra Violet (UV)
  • Each kind is distinguished by a characteristic wavelength, frequency and energy
  • Higher energy radiation can damage our skin

High EnergyLow Energy 7. Colour

  • White light is not a single colour; it is made up of a mixture of the seven colours of ther a i n b o w .

We can demonstrate this by splitting white light with a prism: *Animation 8.

  • The Law of Reflection

Angle of incidence = Angle of reflection The same !!! 9. Clear vs. Diffuse Reflection

  • Smooth, shiny surfaces have aclearreflection:

Rough, dull surfaces have adiffuse reflection. Diffuse reflection is when light is scattered in different directions 10. Refraction

  • The change in direction of a wave as is crosses the boundary between two media in which the wave travels at different speeds.

11. Convex lenses

  • Refracts parallel light rays so they come together at a single point (convergence).
  • Distance from center of lens to focal point = focal length.
  • The thicker the middle of the lens the shorter the focal length.

12. Concave lenses

  • Refracts the rays so they come apart.-Known as divergence.
  • Always forms a virtual image.
  • Show overhead ofconcave lens .