What is a Fuel Video Lecture - Science Class 8 (Old NCERT)

hello friends this video on combustion
and claim part 2 is brought to you by
exam form no more fear from exam so now
that we are talking about substances
which undergo combustion and those which
do not undergo combustion now take one
thing strikes your mind the combustible
substances which we are talking about
what are they they have substantial
which are being burned during which they
are reacting with oxygen and they are
releasing a lot of heat and light so
basically they are producing a lot of
energy in the form of heat so they are
nothing but fuel they are acting as fuel
so fuels are nothing but combustible
substances which release enough heat
energy to be used for domestic and
industrial purposes so basically any
fuel but what is a fuel what kind of
examples comes to your mind when you
think of a fuel you think of coal you
think of petroleum you think of natural
gas these are all examples of fuels for
you picture all these will be these are
all fuels while that is viewers because
they are capable of generating huge
energy how do they generate that energy
by the process of combustion only when
they react with oxygen they are able to
release a lot of energy and that energy
is released in the form of heat and this
processes combustion so basically fuels
are nothing but the combustible
substances but at the same time not all
combustible substances are fuels only
those combustible substance which
release sufficient amount of energy so
that that energy can be utilized for
different purposes for example the
energy that is generated by burning coal
is utilized in several thermal glands to
generate electricity right
similarly the energy that is generated
out of petroleum whether it is petrol or
diesel
so that is used to run vehicles so that
means the energy is huge enough to be
used for different purposes so then
those kind of combustible substances are
fuels let us look at some
samples of fuel so first example is cold
so you can even look at some other
examples like a Trillium wherein you
have petrol diesel these are also
examples of fuel you have example of the
LPG which are there which are just put
inside your cylinder so this also has
efficient if this also generates
sufficient heat energy which helps in
our domestic purpose of cooking
natural gas biogas or cow dung cakes in
fact in villages and rural areas you
would have seen that they Italy do not
use LPG gas cylinders and all they often
use the cow dung cakes and with that
they try to prepare food so cow dung
cakes however there are a lot of
disadvantages associated with the usage
of cow dung cakes because they produce a
lot of pollution they produce a lot of
smoke which is these advantages to the
health of the women preparing food but
yes they are still considered as good
fuels because they generate a lot of
energy Wood is another example of you
will so when you burn wood the energy
generated is huge enough that you can
actually prepare food so it can actually
boil things so that much 8 energy is
generated during the process now when we
talk about a fuel what do you think
defines a good fuel how do we know which
is a good fuel under which is not
because just now I gave you so many
examples I told that cow dung cakes are
also fuel but they are not preferred to
be used because they cause pollution
because they adversely affect the health
of the women now so in a similar way I
mean what are those characteristics
which defines whether of Joule is a good
fuel or a bad fuel so let us quickly
look at the characteristics of a good
fever
first of all it should be easily
available now if that fuel is not
available then I mean then there is no
point because the fuel is not accessible
so we
use it so even though it has a lot of
properties but that doesn't make any
sense it has to be cheap if it is very
expensive then a lot of people will not
be able to use it so it has to be
extremely economical burns easily to
release the heat because a fuel is
something which generates energy in
order to generate energy it has to react
with oxygen now the easily the easier it
reacts with oxygen the better it is
because it immediately actually oxygen
and a lot of energy is released so that
energy release is the most important
thing is the basic definition of a fuel
so it should burn very easily and it
should release a large amount of heat so
the larger the amount of heat it
produces the larger energy it produces
and then that huge energy can be
utilized for different domestic purposes
or industrial purposes does not leave
undesirable residues behind to cause
pollution now this is very very
important when we decide which is a good
fewer language is not now most of the
fuels in fact a lot of fuels they
generate a lot of energy in the form of
heat but at the same time they also
produce a lot of harmful gases they
generate a lot of smoke they leave a lot
of residue after being burnt now even if
you completely burn a particular
substance you see that for example when
you burn vapor what is left behind
you have ashes left behind so now that
is called se-joo so whatever is left
behind after complete combustion of that
substance that is called residue so any
fuel which leaves behind a lot of
residue so what happens to that residue
that receive you if it is sampling which
is harmful then that is waste to our
environment because it is just using
that fuel is actually piling up those
based materials in the environment so
while deciding whether a fuel is good or
not it is very important to check the
type
see to that is being left after the
process of combustion is over and a good
fill is one which does not leave a lot
of undesirable residue so that it
doesn't cause environmental pollution
now it is very important to see that the
fuel which we are categorizing as a good
fuel is good for the environment because
if it is harming our environment then
basically there is no point in
generating energy from such a fuel which
in turn is causing harm to the
environment and is causing harm to us
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