Mirrors and Reflection - Light : Shadow and Reflections - CBSE Class 6 Science Video Lecture

good morning children now we shall learn
about the reflection of light we already
know that light travels in a straight
line and when the light is obstructed by
opaque objects the shadow is formed have
you ever thought is it possible to
change the direction of light let's find
it out we all use mirror to look at our
face the face seen in the mirror is
called image not just mirrors sometimes
we can see our image in clear water or
on a shiny steel plate too so if the
surface of any object be transparent or
opaque is plain and smooth images are
formed any polished or shiny surface can
act as a mirror do you know what happens
when light falls on a shiny and polished
surface such as a mirror let us find it
out together let one person hold a
mirror in his hand and stand at one
corner of the room let the second person
stand at the another corner of the room
let the third person hold a torch and
cover the glass of the torch with
fingers and switch it on let him get a
beam of light by leaving a small gap
between the fingers so that light can
pass through that let him direct the
beam of the torch light onto the mirror
that the first person is holding what do
we see we see a patch of light on the
other side you know now the person can
adjust the direction of the torch so
that the patch of light falls on the
second person standing in the room
Wow interesting to watch isn't it so
what do we conclude now the mirror
changes the direction of the light that
falls on it not just the mirror any
other polished and shining surface like
a shining stainless steel plate can
change the direction of the light this
change of the direction by the mirror or
the light coming back after hitting a
smooth plane surface is called the
reflection of light so the image we see
in the mirror is called the reflection
we can see our image or reflection in
clear water too hence the surface of
water can also act like a mirror and
change the direction of the light in the
story too soon I used the reflection of
the shiny red toy with polished surface
having the shape of a monster to scare
away the thieves that was a good trick
huh you might think why is that when
light is reflected by highly polished
surface like mirror clear images are
formed while the image is formed when
the light is reflected by rough and
uneven surface are not very clear let us
observe the mirror carefully you will be
surprised to know that the our mirror
which looks very smooth also has bumps
you know at a microscopic level that is
when we watch it under the microscope
all surfaces have bumps they are not
smooth actually highly polished surfaces
like mirror have smaller bumps
whereas rough surfaces have much larger
bumps so what is the role of this bumps
the smooth surfaces have very tiny or
unnoticeable bumps therefore they send
back or reflect light in roughly the
same angle the light hits them so we can
see the clear image of the object
objects that are shiny such as metal
pots and mirrors reflect light better
than the rough objects which absorb more
light now coming to rough surfaces when
light faults are hits on a rough surface
with bumps it bounces off in many
directions and back to our eyes we see
our reflections but they are distorted
and not clear this kind of reflection is
called diffuse reflection interestingly
this is the type of reflection that
helps us to see most of the things
around us as the surface cannot be
perfectly smooth normally so now you can
understand why mirror whose surface has
become rough cannot produce clear image
in this case as the surface is no longer
smooth the light is reflected at
different angles and so the image formed
is not clear the more rough the surface
becomes the more unclear or blurred is
the image what is a mirror actually can
we make a simple mirror yes we can
actually it is a plain glass which is
silver-plated the plain glass provides
the smooth surface and the silver
coating makes it shining now how to
prevent light going through the mirror
well for this you will find behind the
silver coating
there is also red paint the red paint
also protects the silver coating from
getting scratched interesting to know
and simple too isn't it
to sum up now we know how to change the
direction of light and what is
reflection the light travels in a
straight line and the mirror changes the
direction of light that falls on it this
change of direction by a mirror is
called reflection of light any polished
or shiny surface say like water - can
act like a mirror and reflect to give
clear images when the reflection is by
the rough surfaces the image is formed
and not clear as the light gets
reflected in various directions and
lastly not to forget a simple mirror is
a plain glass only which is
silver-plated to make it shiny have fun
and enjoy bye bye kids