-- Objects which allows the light
to pass thorough them are called transparent bodies. Eg.
Water, air, glass
-- Objects which do not allow
the light to pass thorough them are called opaque bodies.
Eg. Brick, book, metals, wood etc.
-- Objects which partially allow
the light to pass through them and partially obstruct them
are called translucent bodies. Eg. Brick, book, metals,
-- Light rays always travel in
a straight line path. This property of light is called the
rectilinear propagation of light.
-- Shadows are direct consequence
of rectilinear propagation of light and are formed when
an object is placed in the path of light. Two parts of a
shadow are umbra and penumbra
-- Umbra is the part which is
in complete darkness and receives no light from the source.
-- Penumbra is the part which
is in partial darkness and receives some light from the
-- Shadows resemble shape, but
not necessarily the size, of the object.
-- Object create shadows of different
shapes depending on its orientation or the orientation of
the screen. For example, a cylinder may create a shadow
that is a rectangle or a shadow that is a circle. The shape
of the shadow will always be the same as the cross-section
of the object that lies between the light source and the