Science of Light


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It is a very interesting ppt about the properties of light ,mirrors ,refraction ,colors etc.

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Science of Light

  1. 1. By Khan Imran
  2. 2. What Is Light? In this PowerPoint presentation: 1) 2) 3) 4) Properties of light Colours Reflection - Mirrors Refraction - Lenses
  3. 3. Properties of Light Light travels in straight lines: Laser
  4. 4. 2.Light travels much faster than sound. For example: 1) 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.
  5. 5. 3.Light travels VERY FAST – about 300,000 kilometres per second or 186,000 miles per second. At this speed light could travel the equivalent of 8 times around the world in one second!
  6. 6. 4.Light can create shadows Shadows are places where light is “blocked”: Rays of light
  7. 7. We see things because they reflect light into our eyes! This is literally the only way we get to see things! ALL objects we see either create light or reflect light!! Homework
  8. 8. Light is a form of energy called Electromagnetic Radiation. Electromagnetic Radiation and other sources comes from the sun
  9. 9. Properties of Light summary 1) Light travels in straight lines and is a form of 2) 3) 4) 5) energy Light travels much faster (a million times faster!) than sound We see things because they reflect light into our eyes Shadows are formed when light is blocked by an object Visible light is only a small part of the electromagnetic spectrum; the other parts are invisible to the human eye but not necessarily the eyes of other animals.
  10. 10. Part 2 - Reflection and Mirrors
  11. 11. Regular vs. Diffuse Reflection Smooth, shiny surfaces have a regular reflection: Rough, dull surfaces have a diffuse reflection. Diffuse reflection is when light is scattered in different directions
  12. 12. Review of Reflection 1. Two types of reflection, regular and diffuse 2. Mirrors come in 3 types: plane, convex and concave. Each has a distinct shape and use. 3. Mirrors can make virtual images or real images depending on their type 4. Virtual images - light rays do not meet and the image is always upright or right-side-up 5. Real images - always upside down and are formed when light rays actually meet
  13. 13. Using mirrors Two examples: 2) A car headlight 1) A periscope
  14. 14. Types of Mirrors: Plane, Concave, Convex Plane mirrors are flat and make “virtual images”. The images is “virtual” because the light rays do not come from the image, they only appear to
  15. 15. Concave Mirrors are curved inward - just remember, you go “in” to a cave, and “in” to a concave mirror!
  16. 16. Convex mirrors are mirrors that curve outward Convex mirrors are used for security purposes, in cars etc. They allow us to see a wide view. The images they make are virtual
  17. 17. Refraction •Refraction is when waves speed up or slow down due to travelling in a different medium •A medium is something that light waves will travel through •Light rays are slowed down by the water •Causes the ruler to look bent at the surface • The mediums in this example are water and air .
  18. 18. The degree that light bends when it enters a new medium is called the “index of refraction”
  19. 19. Light hitting at an angle is bent Light hitting straight on is not bent
  20. 20. Review of Refraction 1. Light rays slow down when they enter a new medium 2. Refraction can cause light rays to change their direction 3. All transparent materials have their own “index of refraction” 4. Light is refracted when it passes through lenses and this creates images
  21. 21. Color Part 3 - Color In this section of the PowerPoint you will learn about color and how we can mix colors to create other colors. We will also learn how light helps us to see various colors around us.
  22. 22. Colour White light is not a single colour; it is made up of a mixture of the seven colours of the rainbow. We can demonstrate this by splitting white light with a prism: This is how rainbows are formed: sunlight is “split up” by raindrops.
  23. 23. The colours of the rainbow: Red Orange Yellow Green Blue Indigo Violet Just remember ROY G. BIV
  24. 24. Adding colours of light White light can be split up to make separate colours. These colours can be added together again. The primary colours of light are red, blue and green: Adding blue and red makes magenta (purple) Adding red and green makes yellow Adding blue and green makes cyan (light blue) Adding all three makes white again
  25. 25. Seeing colour The colour an object appears depends on the colours of light it reflects. For example, a red book only reflects red light: White light Only red light is reflected
  26. 26. A pair of purple trousers would reflect purple light (and red and blue, as purple is made up of red and blue): Purple light A white hat would reflect all seven colours: White light