L3 : Celsius Scale; Fahrenheit - Heat, Science, Class 7 Video Lecture

hello friends this video on heat part 3
is brought to you by exam for your calm
no more fear from exam so how do we
distinguish the different scales of
temperature or how do we I mean what is
the common basis on which we have
divided these different scales of
temperature so there are no fixed
reference points for measuring
temperature and those two points are ice
point and steam point so what is ice
point so ice point is nothing but the
freezing point of water it is that
temperature at which water starts to
freeze that is water what happens when
water freezes what our freezers to form
ice and what happens when water boils it
boils to form water vapour right so this
is ice and this is water and vapor and
this is water right so I spoil is
nothing but the freezing point of water
so it is the point at which water gets
converted into ice and when we talk
about steam point it is the boiling
point of pure water that is it is that
temperature at which water starts
getting converted into water vapour now
in all the three scales we have
determined to the ice point and the
steam point so every scale for example
in Celsius scale we will have a fixed
ice point and a fixed steam point
similarly in the Fahrenheit scale we
will have a fixed end point and a
16-point and that is how we will be able
to find out a relation between the
various scales of temperature like when
we talk about meters kilometers for
distance so there is a relationship that
exists between meter and kilometer also
only then we will be able to understand
how much is 10 kilometers so how did we
see that 10 kilometer is 10
meters because we know that one
kilometer is equal 2,000 meters so that
relation had to be established between
the different scales of temperature also
so for that we take these two reference
points that is ice point and steam point
so let us look at the various scales of
temperature which we will be discussing
right now so the first one is the
Celsius scale which was also known as
the centigrade scale so centigrade and
Celsius the refers to the same scale so
this is often denoted as degree Celsius
this is how we denoted the next one is
Fahrenheit scale which is denoted by F
and it was named after the scientist
Fahrenheit who described it for the
first time so Sencha scale so it was
Celsius was named after the Swedish
Xtranormal Celsius who discovered it for
the first time so in this scale the ice
point is at zero Degree and the steam
point is at 100 degree Celsius so you
see this is the ice point and this is
the steam point so in between these you
have the various temperatures so as I
said ice point and steam point they are
the two reference points for all the
scales of temperature so let us look at
the Fahrenheit scale so this Celsius
scale is also called centigrade scale -
is this why we measure temperature we
see we often read this thirty degree as
thirty degree Celsius or thirty degree
centigrade so they both mean the same
the next one is Fahrenheit scale here
the ice point is 32 degree Fahrenheit
and the steam point is 212 degree
Fahrenheit so that means a zero degree
Celsius is equivalent to a 32 degree
Fahrenheit because the temperature at
which water starts to freeze that is the
point so that temperature in Celsius
scale is zero degree and the same
temperature in Fahrenheit scale is 32
degrees so that's how the Celsius and
the Fahrenheit scale gets related to
each other
so it was named after Fahrenheit who had
proposed this scale so it is denoted by
a degree s followed by F which denotes
Fahrenheit so let us quickly look at the
relationship between Celsius and
Fahrenheit so if you try to compare the
two scales you will see that a hundred
degree Celsius is equivalent to a 212
degree Fahrenheit and the zero degree
Celsius is equivalent to a 32 degree
Fahrenheit because this denotes the
steam point and this temperature denotes
the ice point so if you want to convert
any temperature in Celsius to a
temperature in Fahrenheit so how do you
do that so there exists a relationship
between Celsius and Fahrenheit that is
TC by 5 is equal to TF minus 32 by 9 so
we will not get into the derivation
right now but so you can just have a
look at this for with us so this TC is
nothing but the temperature in Celsius
scale and TF is nothing but the
temperature in Fahrenheit scale so let
us suppose if you take an example of a
temperature which is 20 degree Celsius
so basically TC is equal to 20 degree
Celsius so let us see how much it would
be in the parent head state so in the
picture you can see that it is 68 degree
Fahrenheit but let us try to calculate
it using this formula so the formula
becomes 20 by 5 is equal to TF minus 32
by 9 so this will be 5 for 20 so this is
TF is equal to 36 plus 32 so this is
equal to 68 degree Fahrenheit so
therefore we can say that a 20 degree
Celsius
equivalent to a 68 degree Fahrenheit
similarly we can convert the Fahrenheit
scale values into Celsius scale also
cell for example let us see the ice
point so how much is the ice point on
essentia scale so on a Celsius scale it
is zero degree Celsius so if we put this
value of zero in this equation so what
do we get we get 0 is equal to TF minus
32 by 9 so this becomes equal to TF is
equal to 32 degree Fahrenheit so
basically the ice point on Fahrenheit
scale should be equal to 32 degree
Fahrenheit so similarly you can do it
for the steam point as well let now let
us talk about our body temperatures
because we have been taking examples of
our body temperatures that when we are
healthy for a healthy person the normal
body temperature is somewhere around 98
degree approximately 98 degree and this
is in Fahrenheit so let us see how how
much is the normal body temperature in
both Celsius and Fahrenheit scale so in
Celsius scale the normal body
temperature normal body temperature in
Celsius scale is 37 degree Celsius
so again if you put these values in the
equation TC by 5 is equal to TF minus 32
by 9 so using this you see that 66.6 is
equal to TF minus 32 or we can say that
TF is equal to 66.6 plus 32 so this is
equal to 98.6 degrees fahrenheit so this
is the normal temperature of human body
in Fahrenheit scale so now you
understand where
they say that the temperature of boiling
what it is 100 degrees Celsius okay so
for boiling water the temperature is 30
100 degree Celsius and for our human
body the temperature is 98 degree
Fahrenheit so 98 degree Fahrenheit is
basically 37 degree Celsius which is a
lot less than that of the boiling water
that is why our body is not even
comparable in hotness when compared to
the boiling water pan thank you please
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