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There have been
five main
temperature
scales, each one
being named
after the person
who invented it.
G D FAHRENHEIT
(1686-1736) a
German
physicist, in
about 1714
proposed the
first practical
scale. He called
the
freezing-point
of water 32
degrees (so as
to avoid
negative
temperatures)
and the
boiling-point
212 degrees.
R A F de REAUMUR
(1673-1757) A
French
entomologist,
proposed a
similar scale in
1730, but set
the
freezing-point
at 0 degrees and
the
boiling-point at
80 degrees. This
was used quite a
bit but is now
obsolete.
Anders CELSIUS
(1701-1744) a
Swedish
astronomer,
proposed the
100-degree scale
(from 0 to 100)
in 1742. This
was widely
adopted as the
centigrade
scale. But since
grades and
centigrades were
also measures of
angle, in 1947
it officially
became the
Celsius scale.
Also, the S I
system of units
gives preference
to naming units
after people
where possible.
William Thomson,
1st Lord KELVIN
(1824-1907) a
Scottish
mathematician
and physicist,
worked with J P
Joule - about
1862 - to
produce an
absolute scale
of temperature
based on laws of
heat rather than
the
freezing/boiling-points
of water. This
work produced
the idea of
'absolute zero',
a temperature
below which it
was not possible
to go. Its value
is -273.15
degrees on the
Celsius scale.
William J M
RANKINE
(1820-1872) a
Scottish
engineer and
scientist,
promoted the
Kelvin scale in
its Fahrenheit
form, when the
equivalent value
of absolute zero
is -459.67
degrees
Fahrenheit.
Nowadays, while
scientists use
the KELVIN
scale, the
CELSIUS scale is
the preferred
scale in our
everyday lives.
However, the
Fahrenheit scale
is still widely
used and there
frequently is a
need to be able
to change from
one to the
other.
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To
change
temperature
given
in
Fahrenheit
(F)
to
Celsius
(C)
Start
with
(F);
subtract
32;
multiply
by
5;
divide
by
9;
the
answer
is (C)
To
change
temperature
given
in
Celsius
(C)
to
Fahrenheit
(F)
Start
with
(C);
multiply
by
9;
divide
by
5;
add
on
32;
the
answer
is (F)
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