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Properties of light
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Properties of light


please study

please study

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  • 2. Light
  • 3. Part 1 – Properties of Light
    • Light travels in straight lines:
  • 4.
    • Light travels VERY FAST – around 300,000 kilometres per second.
    At this speed it can go around the world 7.5 times in one second.
  • 5.
    • Light travels much faster than sound. For example:
    • Thunder and lightning start at the same time, but we will see the lightning first.
    2) When a starting pistol is fired we see the smoke first and then hear the bang.
  • 6.
    • Luminous and non-luminous objects
    A luminous object is one that produces light. A non-luminous object is one that reflects light. Luminous objects Nonluminous objects
  • 7.
    • Shadows
    Shadows are places where light is “blocked”: Rays of light
  • 8. Properties of Light summary
    • 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
  • 9. How do we see objects?
  • 10.
    • We see things because they reflect light into our eyes:
  • 11. Reflection
  • 12. Reflection of Light
    • is the phenomenon of wave motion, in which a wave is returned after impinging on a surface.
  • 13.
    • Types of
    • Reflection
  • 14.  
  • 15. Specular Reflection
    • Reflection off of smooth surfaces such as mirrors or a calm body of water.
  • 16. Diffuse Reflection
    • Reflection off of rough surfaces such as clothing, paper, and the asphalt roadway.
  • 17.
    • Applications
  • 18.
    • One application pertains to the relative difficulty of night driving on a dry asphalt roadway compared to a wet asphalt roadway.
  • 19.  
  • 20. The Law of Reflection The incident ray, the reflected ray, and the normal to the surface all lie in the same plane, and the angle of reflection θ r equals the angle of incidence θ i.
  • 21.  
  • 22.
    • The ray of light approaching the mirror is known as the incident ray (labeled I in the diagram). The ray of light which leaves the mirror is known as the reflected ray (labeled R in the diagram).
  • 23.
    • At the point of incidence where the ray strikes the mirror, a line can be drawn perpendicular to the surface of the mirror; this line is known as a normal line (labeled N in the diagram).
  • 24.
    • The angle between the incident ray and the normal is known as the angle of incidence .
  • 25.
    • The angle between the reflected ray and the normal is known as the angle of reflection .
  • 26. Reflection
    • Reflection from a mirror:
    Incident ray Normal Reflected ray Angle of incidence Angle of reflection Mirror
  • 27.
    • The Law of Reflection
    Angle of incidence = Angle of reflection In other words, light gets reflected from a surface at ____ _____ angle it hits it. The same !!!
  • 28.