James Prescott Joule (24 December 1818 – 11 October 1889) was
an English physicist, born in Salford, Lanashire, England. He came
from a wealthy family who was involved in the brewing industry.
As a child, James was weak and shy, and suffered from a spinal
disorder. Because of these limitations, he preferred studies to
physical activity.
He was educated at home by private tutors until the age of
fifteen. He then went to work in the family brewery as his father
became ill. However, he and his older brother continued their
education part-time with private tutors in Manchester. They were
taught chemistry, physics, the scientific method, and
mathematics by the famous scientist John Dalton.
Although he only received two years of education from John
Dalton, these teachings were what made him one of the most
exact measurement takers of his day. It made him form a desire
to increase his knowledge by original researches.
John Dalton
His great desire was to continue
to study science, so he set up a
laboratory in his home and
began to study electric motors
and experimenting before and
after work each day. His
brewing hobby also becomes
his first time to use physics.
Making all of his machines and
devices more efficient is where
his skills for physics came to
shine. In doing this his studies
with energy began.
Joule had the idea that he could use the electric motor to convert the family
brewery from steam power to electric power. He spent a great deal of his life in
determining the mechanical equivalent of heat, inspired from his belief that heat
was derived from work. By the 1840s, scientists had realized that heat, electricity,
magnetism, chemical change and the energy of motion were all interconvertible. Joule was extremely involved with this work, and between 1837 and
1847, he established the principle of conservation of energy, and the
equivalence of heat and other forms of energy. He was fascinated by the
possibility that electromagnets might become useful as sources of industrial
power. He began to link together electricity, heat and mechanical power by
observing the transformations they went through. By 1840，he established that
the amount of heat produced per second in a wire carrying an electric current
equals the current (I) squared multiplied by the resistance (R) of the wire. The heat
produced is the electric power lost (P). (That is, P=I2R.), which is Joule's Law.
Still with the idea that it was possible to convert mechanical work
directly into heat without any electrical steps, Joule experimented
from 1842 to 1878 on such conversions. Around 1845, he was able
to demonstrate in a paddle-wheel experiment, which involved
the shaft and paddles being driven by a falling weight suspended
from a pulley, that the same amount of work, however done,
always produced the same amount of heat. This enabled Joule to
conclude that heat was a form of energy. The mechanical
equivalent of heat is a constant and is designated by the
symbol J in honour of James Joule.
Joule displayed an amazing clarity in conceiving, executing,
describing and explaining his experiments. Joule’s work on the
relationship of heat, electricity and mechanical work was largely
ignored until 1847. While Joule was not the first scientist to suggest
this principle, he was the first to demonstrate its validity. He
showed that “work can be converted into heat with a fixed ratio
of one to the other, and that heat can be converted into work.”
Joule’s principle of energy conservation formed the basis of the
first law of thermodynamics. This law states that energy can
neither be created nor destroyed, but it can be changed from
one form into another.
James Prescott Joules was a determined
scientist who never gave up on his research or
experiments to prove his theories. Although his
papers were responded by the Royal Society
and the journalists unenthusiastically, he
patiently persisted until 1847, when William
Thomson finally took notice of his work on the
relationship
of
heat,
electricity
and
mechanical work.
Other than that, he was very humble about his
discoveries as he cared more about the results
of his experiments than his recognition for
them. Most importantly, he was committed to
his research to prove his theories and never
gave up on his work.
All of these values definitely have inspired us to
continue learning Science, to be scientists and
maybe one day, we can discover and
develop a theory and contribute it back to the
scientific world and impart knowledge to
others and benefit them.
We have learnt more about James Prescott Joule, one of the
greatest scientists in the world, about his beneficial discoveries
and know how important Science is and how it can improve our
lives. We have learnt that perseverance and determination are
the keys to becoming a great scientist, and at the same time, be
humble about our discoveries.
However, as physics is an area consisting of many different
topics, we were confused at times whether his major contribution
was electricity or heat. In the end, we did more research and
found out more about his contributions, which were mostly heat.
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http://en.wikipedia.org/wiki/James_Prescott_Joule
http://simple.wikipedia.org/wiki/James_Prescott_Joule
http://www.zephyrus.co.uk/jamesjoule.html
http://www.answersingenesis.org/articles/cm/v15/n2/jamesjoule
https://thescienceclassroom.wikispaces.com/James+Prescott
+Joule
http://www.google.com.sg
Done by:
Liaw Wan Qing (6),
Lorraine Lim Wen Jing (8),
Wee Yu Xuan (21)