The sun, earth , moon
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CHAPTER – 10
The sun, earth , moon – light and shadow
How do we
see anything?
we can see different objects only in the presence
of light. Actually when a beam of light falls on an object from the source of
light then this light gets reflected in all directions after striking that
object. The reflected light then reaches our eyes and we become able to see
that object.
The sun- a
source of light
The sun is a
star. It produces heat and
light all the
time. We are able to see objects
during the day
because of sunlight.
The moon
The moon is the
brightest object in the night sky, but it does not have light of its own. The
moon appears bright because light from the sun falls on it .
The moon is the Earth’s natural satellite. It revolves around the
earth . It also rotate on its own axis.
Light travels in a straight
line
Light always
travels in a straight line .
Formation of
shadows
v An
object which does not let light pass through s called an opaque object.
We cannot see through an opaque object.
Examples : wood ,stone , metal ,etc….
When an opaque
object comes in the path of light , light cannot travel further , it gets
stopped. When light is stopped n it path
by an object , a dark area is formed on a surface behind the object. This dark
area is called a shadow.
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The object which forms a shadow is always between the source of light and the
shadow.
v Objects
made of clear glass and plastic allow light to pass through them completely.
Such objects are said to be transparent.
We can see through a transparent object. A transparent object does not
form clear shadow.
v Some
objects allow only some amount of light to pass through them. Such objects is called translucent.
Examples – plastics and glass are
translucent material.
We cannot see through the translucent
object clearly.
Translucent objects form faint shadows.
The
size of the shadow depends on the distance between the source of
light and the object.
The
position of the source of light from the object affects the size of the shadow.
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