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.

 

µ 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.