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LIGHT

LIGHT. Sources of Light. Sun Fire Lamp Torch. Sources which give out light are said to be luminous . Transmission of Light. Light travels at a speed of 300 million miles per second Light can travel through a vacuum and also through transparent substances e.g air, water and glass

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LIGHT

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  1. LIGHT

  2. Sources of Light • Sun • Fire • Lamp • Torch

  3. Sources which give out light are said to be luminous

  4. Transmission of Light • Light travels at a speed of 300 million miles per second • Light can travel through a vacuum and also through transparent substances e.g air, water and glass • Most substances do not allow light to travel through it these absorb some of the light and reflect some also

  5. Cloud  absorbs + reflects light but also allows some light to shine through

  6. Eyes = Light Detectors

  7. Light is a form of energy • How do we know this?? • 1. Light comes from other forms of energy (sun, fire etc) • 2. Light can also be converted to other forms of energy • Examples!

  8. Examples

  9. Light travels in straight lines • Examples: the beam from a torch, spotlight or carlight • A narrow beam of light which travels from a source is called a ray • Mandatory Experiment

  10. Shadows • Some substances stop light from passing through them  Opaque • This is how shadows are formed, rays passing near the object are blocked • Mandatory Experiment

  11. Example

  12. Eclipses

  13. Reflection of Light • Reflection is the bouncing of light from a surface • Most surfaces, on a microscopic scale, are full of humps and hollows – these reflect light in many directions • Exception - A mirror . The surface of a mirror is smooth, flat and polished so the light is reflected in a regular orderly way

  14. Periscopes • These allow people to see things that otherwise would be difficult to see

  15. Uses of Reflection • We can see non-luminous objects because they reflect light • Periscopes use reflection to see objects that otherwise would be difficult to see • Reflective mirrors in cars are used for safety. Drivers can see whats happening behind them • Normal mirrors use reflection so that we can see our own appearance • Microscopes often use mirrors to direct light onto the slide

  16. Refraction of light • Refraction is the bending of light as it passes from one medium to another

  17. Convex Concave

  18. Applications of Refraction • Lenses Contact lenses, glasses, magnifying glasses, microscopes

  19. 2. Mirages

  20. 3. Rainbow

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