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    الصف الخامس unit 1 2011

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    atwa
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    الصف الخامس unit 1 2011

    مُساهمة من طرف atwa في الثلاثاء أكتوبر 12, 2010 10:20 pm

    Light
    *Is light a form of energy
    - The part of light energy that can be seen is called “the visible spectrum”.
    The visible spectrum: It is the light energy that can be seen.
    Sources of light مصادر الضوء
    1. The Sun which is the main source of light on Earth,
    * moonlight also it reflect sunlight that falls on it
    2. Lightened electric lamps, lightened candles and kerosene lamps.
    The properties of light خواص الضوء
    1- Light travels in straight lines.
    2- Light transmits through different materials.
    3- Light reflection.
    4- Light refraction.
    5- Light separation (splitting) ( analyze )تحلل الضوء .
    First: Light travels in straight lines
    Formation of shadow is due to travelling of light in straight lines.
    * The formation of images through narrow holes inverted مقلوبة .
    due to light travels in straight lines.
    *Shadow : it is darkness area which is formed due to falling of light on opaque object .
    * second :Light transmits through different materials.:
    a. Transparent materials.
    b- semi –Transparent (translucent) materials
    c. Opaque materials.
    a. Transparent material: المواد الشفافة
    It is the material which lets most light pass through and objects can be seen clearly
    As Air. -A glass cup -Clear water..
    b. Semi -transparent (translucent) material:
    It is the material which lets some light pass through and objects can be seen through it less clearly than the transparent one.
    As : tissue paper - Frosted light bulbs
    c. Opaque material: It is the material that doesn’t allow light to pass through and objects can’t be seen through it.
    As Rocks - Foil paper - Wood - Books - Cartoon - People .
    Third: The light reflection. انعكاس الضوء
    It is the bouncing (returning back) of light rays when light falls on a reflecting surface
    • Factors necessary for light reflection:
    1. A source of light. 2. A reflecting surface.
    • Types of light reflection:
    a. Regular reflection b. Irregular reflection
    Regular reflection: انعكاس منتظم
    It is the reflection of light on a smooth and shiny reflecting surface
    where the light rays are reflected directly in one direction.
    As :Reflection of light when it falls on a mirror surface.

    * Seeing your image in the mirror.
    Because the mirror reflects the light rays falling on it.
    irregular reflection: انعكاس غير منتظم
    It is the reflection of light on a rough reflecting surface, where the light rays are reflected and
    scattered in different directions.

    Reflection of light when it falls on any rough surface as a piece of
    white paper
    Fourth: light refraction انكساء الضوء
    It is the change in the direction of light rays when light passes through the separating surface between two transparent media, due to the change in the light speed.
    * the speed of light in air is greater than water
    spoon appears broken when you put it in a transparent cup of water.
    • Due to the refraction of light.
    Fifth :Separation (splitting) ( analyzing ) of Light. تحلل الضوء

    It is the separation of white light into seven colors called spectrum colors.
    * the spectrum colors are
    Red - orange – yellow – green – blue – indigo – violet
    *- White light can be also analyzed into the seven spectrum colors by the
    drops of rain water forming rainbow.
    *- Rainbow appears in the sky after rainfall.
    *Rainbow is produced when white sunlight passes from the drops of rain water to air, then its splitting into seven spectrum colors, so the rain water acts as a prism.
    Seeing colored objects
    • mixing the seven light spectrum colors produces the white light .
    the colored objects
    • seeing the colored transparent objects : they absorb all colors and permits its own color to pass
    example : green transparent bottle
    • seeing the colored translcent objects : they absorb all colors and permits its own color to pass
    • seeing the opaque object
    white object : reflect all the light colors
    the black objects : absorbs all the light colors
    • the colored objects : absorbs all colors and reflect its own color.
    Example : the color of apple


    Mixing the color lights خلط الالوان
    *The primary colored light : they are impossible to produce by mixing two colored light .
    • they are ( red - green – blue )
    *The secondry colored light : they are produced by mixing two of primary colored lights .
    * they are ( yellow - cyan – magneta )
    red + green = yellow
    red + blue = magneta
    blue + green = cyan

    Magnetism المغناطيسية
    Types of magnet are
    1-Natural magnet 'طبيعى
    * It is a black rock.
    Or one of the iron ores which is known as “Magnetite”
    2-Artificial (man-made) magnet: صناعى :It has different shapes and sizes.
    Rectangular magnet - Horse-shoe magnet - Magnetic needle - Bar magnet - Ring (round magnet)
    *magnetic materials : المواد المغناطيسية
    They are the materials which are attracted to the magnet.
    As Iron, nickel, steel and cobalt.
    *non-magnetic materials : المواد الغير مغناطيسية
    They are materials which are not attracted to the magnet

    As :Chalk, glass, paper, aluminium, copper, wood, leather and plastic.
    The properties of the magnet :خواص المغناطيس
    * The magnet has two poles.
    * The freely moving (suspended) magnet always takes a fixed direction, which is North-south direction.
    * The like (similar) magnetic poles repel each other, but the unlike (opposite) magnetic poles attract each other.
    * The magnet is surrounded by an area called “Magnetic field”.
    first : The magnet has two poles.
    The magnetic pole. القطب المغناطيسى : it is The regions (areas) of magnet at which most of the magnetic materials are attracted.
    Or The regions of magnet at which most of the attraction force is concentrated
    .second : The freely moving (suspended) magnet always takes a fixed direction, which is North-south direction.
    The pole of magnet which points to the north direction is called “north pole'(N) but which points to the south direction is called “south pole(S)”.
    * Magnetic force disappears in the middle

    * the north pole usually red-colored but the south pole is usually blue -colored
    * The similar (like) magnetic poles repel each other, but the opposite (unlike) magnetic poles attract each other.
    * the magnetic field المجال المغناطيسى :
    It is the space around the magnet in which the effect of magnetic force appears.
    Or It is the ability of the magnet to attract the magnetic materials existed in its field.
    The magnetic force is an invisible one so, we use iron filings to show the magnetic field that is formed by the effect of magnetic force.
    The use of magnet : the compass البوصلة
    • The structure of magnetic compass:
    It consists of:
    A light and small magnet that can spin freely around a fixed axis
    • The importance of the magnetic compass:
    It is used to identify the four geographical directions.














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