Light travel along straight line - Light Shadow & Reflection, Science, Class 6 Video Lecture

hello friends this video on light
shadows and reflection part 5 is brought
to you by exam for calm no more fear
from exam now that we got this basic
idea about how light interacts with veil
is objects now let us see what exactly
is light so light is as I have mentioned
before it is something that enables us
to see so it is a form of energy which
enables us to see things around us if
you talk about how light travels it
always travels along a straight path now
many a times you might feel that Hey is
it that light travels along a straight
path because when I keep my window panes
opened the entire room get lit up so
that means that light is able to reach
every corner of the room so how can you
say that light travels on a straight
path so we will do few experiments to
prove that light travels along a
straight line speed of light is then
huge light travels at a very high speed
of around 3 into 10 to the power 8 meter
per second which is an extremely high
speed now quite surprised with the fact
that light travels along a straight line
so it is do this simple experiment take
a burning candle ok so light is present
there because the flame of the candle
that reduces light but if possible
darken the room so that you just have
the light coming out from the candle now
you take a cylindrical object like this
a hollow cylinder or tube like structure
and try to see through the tube what do
you see
you will be able to see the light coming
from the candle the light which is being
produced by the flame of the candle now
you try the same thing in a slightly
different way instead of the straight
tube you try to see the same thing
through a bent tube the tubes is the
same tube if you get if you can have a
tube which is
flexible enough that you can bend it so
just bank the tube and try to see
through it now this time you will not be
able to see the light you will not be
able to see anything inside the tube
it'll be completely dark why is that
that's because light travels along a
straight path so when you are seeing it
at it through something which is
straight you are able to see the light
now that you are seeing it through
something which is bent so the light
doesn't seem to be seen that's because
light cannot bend light all these
travels along a straight path so we will
perform another experiment which will
very clearly demonstrate that light
travels a long straight path so for this
you would need some playing cards
so take some playing cards make holes at
the center of each of them and now you
take a laser light now if you have not
seen a laser light you will get it in
any stationery shop or maybe you will
find it in the lab of your school so
basically the laser light it produces
the thin a narrow beam of light it's
like one strong intense beam of light
but it's very distinctly seen as a line
so and then you put the laser light on
these cards and what do you see you will
see that this light will be clearly seen
to be passing through the holes of all
the cards now you have arranged place
the cards in such a way that all the
holes of the cards lie along a straight
line so you will be able to see this
laser light coming out of the last card
very clearly now what you do is and you
will also see the presence of the laser
light on this on a screen on this side
now all that you need to do is you just
remove one card in this way so just this
move this plays one of the cards in such
a way that this hole doesn't light here
now then what happens you will see that
the light doesn't Bend
so if light had the option to bend it
could have been delayed
this and then again it could have gone
like this but since light cannot bend it
to just travel straight when it reached
here it couldn't find the hole so there
was nothing which put a law at the card
being an opaque object didn't allow
light to move further and that's why it
was blocked and it was not seen on the
screen thereafter so this shows that
light cannot Bend so even though you had
a provision for light to move through
this hole but light could not bend to
pass through this hole so this
experiment very clearly tells that light
can travel only along a straight path so
this is a very simple experiment which
you can perform at your home because you
do not need a lot of things just a
couple of playing cards and a laser
light in fact you can try the same thing
with a porch light as well thank you
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