Convection of Heat Explanation by Experiment Video Lecture | Science Class 7 (Old NCERT)

hello this we know that one mentions the
process of heat transfer from one place
to another by actual movement of the
molecules visible perform a very simple
experiment that will illustrate the
phenomenon of convection will take a
small glass container with a tight lid
we are going to make two holes on the
lead one big hole and the other one is a
small hood now the big hole should be
big enough that a straw exactly fits
into the wood so heat the night enough
in the candle flame for the small hole
we make use of the divider because this
will need to be really tight
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put the straw inside the big hole make
sure that the base of the straw doesn't
touch the base of the container so the
first little bit of space at the bottom
now from the top just leave little
portion of the straw visible on the top
and cut the rest of it just to ensure
that there is no leakage from the
stadium we seal this area with dough now
we fill this small container with some
boiling hot water mixed with dye
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make sure that you close the heat very
effectively such that there is no leak
anyway now we are taking another law
transparent container filled with cold
water so what we have like to do is we
put this small container inside the big
container now as you see that the base
of this big container is not smooth so
for that purpose we will make use of
this cap on and we will protect you so
that this can act as a smooth platform
for this small container what do you see
you see the ink solution is coming out
of the straw and it is moving upwards
now why it does not happen now hot
solution is less dense therefore it
moves up the molecules of the solution
themselves move and therefore transfer
heat from one place to another and this
is convection so this simple experiment
very clearly illustrates the phenomenon
of convection now you may ask that what
was the purpose of making the second
angry hole over the lead of the
container
well this hole allows air to move into
the small jar so that the pressure
created make moves the solution out of
the straw
now as this process of perfection
continues you will see that this process
of convection would continue only as
long as the difference in temperature
exists so after some time water and the
solution they both reach the same
temperature that is the entire system
attains equilibrium and therefore the
heat transfer stops that is convection
stops I hope you liked the video like it
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you