Page 156 - Science Class 06
P. 156
SHADOW
During the day and scorching sun, we want Aim : Do transparent materials cast
to take rest in the shadow under a tree or their shadow?
others object. A shadow protects us from
the scorching sun. It is because tree is an Materials required : A piece of fine glass,
opaque material that do not allow the light a torch, a screen stand.
of the sun to pass through it. It obstructs Method : Arrange the piece of glass in a
the light. But a roof made of fine glass stand and light the torch in front of it. Is
cannot protect us from the scorching sun. It there a shadow on the screen? No. Why?
means opaque materials are required to Actually the light coming from the torch
cast shadow. passes through the piece of glass. The
piece of glass does not put any obstacle
in the path of light, that is why, it does
not cast a shadow.
Important Facts about Shadow Forma on
v Shadow forma on of various objects of
different sizes:
The size of shadow formed by an
opaque material depends upon the size
of the beam of light and the opaque
material.
A man res ng in the shadow under a tree.
If the beam of light coming from a
Forma on of a Shadow
source of light such as torch, is smaller
Some mes, objects can block light which than the size of an opaque material, the
means that no light is able to pass through shadow formed will be greater than the
that object. An object from which no light object. But, if the size of the beam of
can pass through is called an opaque light is bigger than the size of the
object. The easiest example is our body. opaque material, the shadow formed
Stand in the way of a beam of a light from a will be smaller than the opaque
small torch. Ask someone to stand behind material. Look at the following figure.
you and spot the beam of light. The person
behind you will see no light since your body Cast shadow
Shadow cone
did not allow it to pass. Whenever light is
Core shadow
not able to go through an object, it creates
a dark area around the object. This patch
where the light cannot reach is called a
Screen
shadow. Opaque objects create clear dark Sphere Source of Light
shadows.
156 Science-6
