Light

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Light

• Chapter 47

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Light

• Light is a form of Energy because it can make
  things move.
• Examples
• Crookes radiometer
• Solar powered calculator.

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Light travels in straight lines.

• Experiment to show that light travels in straight
  lines.

If the middle card is moved the light cannot be
seen.
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Shadows
Shadows can be explained by the fact that light
travels in straight lines. A shadow is total or
partial darkness behind an object blocking the
light.
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Solar Eclipse

• One of the most spectacular
• shadows is the
• solar eclipse where the moon passes
• between the earth and the sun.

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Reflection

• Light bounces off or reflects off a surface. A
  shiny polished surface (a mirror) reflects rays
  of light in a regular orderly manner.

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A Periscope
A periscope is an example where light rays are
reflected off mirrors.
The mirrors are positioned at 45 angles. The
light rays reflect off the top mirror, down to
the bottom mirror and then to the eye.
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Refraction

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

The light ray gets pulled towards the denser
substance.
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Lenses
Lenses refract or bend light passing through them.
Convex Lens (converging lens)
Concave Lens (Diverging lens)
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Convex lens(converging lens)
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Concave Lens(Diverging lens)
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Colour

• Dispersion of white light is the breaking of
  white light into its colours.

The prism disperses the white light into
different colours.
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Dispersion
A good example of dispersion is a rainbow.
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Newtons disc
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Primary Colours

• The primary colours of light are Red Green and
  Blue. These combine to give white light.
• Secondary colours are formed by mixing any two
  primary colours together.
• Red Green Yellow
• Green Blue Cyan
• Blue Red
  Magenta

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Action of the eye