science primary 5 new

المدير العام علم بلدك :

Unit 1 : Energy
Lesson 1 : light

Light :
A form of energy that affects eye
causing the sense of seeing (vision )
Difference
between light energy and other forms of energy :
Lightenergy differ than other kinds of energy
Because :
It is visible energy .
Sources of light
:
1. The Sun :
The main source of light on earth's
surface
2. The moon :
Moon's light is a reflection of
sunlight that falls on its surface .
Visible Spectrum
:
Light energy which can be seen by the
eye

Travel of light

v Light travels in straight lines .
Example :
The Straight line :
is The path
1.Which is taken by light rays coming
from the car torch .
2.Which is taken by beam of sun rays
coming from the sun and passes through a narrow hole of a window or a
dark room
Activity prove
that :
Light travels in straight lines
Tools : lighted candle – straight cylinder of length
50 cm
Steps :
1.Fix a lighted candle vertically
2.Put one of the 2 ends of the straight
cylinder
in front of the candle flame
3.Look at the flame of the candle .
Observation :
You can see the flame
4.Bend the cylinder (not straight )
5.Try to look at the candle flame
through the bent cylinder
Observation :
You can't see the flame.
Conclusion :
Light travels in straight lines

Activity prove
that :
Light travels in
straight lines
Tools :lighted candle – 3 cardboard screens
Steps :
1.Bring 3 pieces of cardboard , each
containing a hole .
2.Put them in a row in front of a
lighted candle .
Where all holes and the flame are on one
straight line .
3.Look to the candle flame through the
hole of the last pieces of cardboard .
Observation :
You can see the flame
4.Move any of the pieces of the
cardboard to right or left
The 3 pieces are not on one straight line .

5.Try to see the candle flame through
the hole of the last pieces of cardboard .
Observation :
You can't see the flame .
Conclusion :
Light travels in straight lines
Phenomena happen
due to traveling the light in straight lines :
1.Formation of images through narrow
holes
2.Formation of shadows
Formation of
images through narrow holes :
When light travels through
narrow holes :
An inverted image is formed is formed
It leads to :
Designing of photographic camera .
Activity proves
that :
Light travels
through narrow holes forming An inverted image :
Steps :
1.Bring a cardboard ( metallic ) box
opened from on side .
2.Cover the open side by a
semi-transparent paper (white balloon )
3.Make a small hole on the opposite side
of the box.
In a dark room :
4.Move a lighted candle in front of the
small hole
of the cardboard box Until an inverted
is formed .

Observation :
An inverted image for the candle is
formed
Conclusion :
Light travels through narrow holes in
straight lines forming An inverted image .

v
This activity
is the base of idea of the camera
v
This box is called
pin-hole camera
by

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موضوع: رد: science primary 5 new الجمعة 13 مايو 2011, 11:57 pm

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