joule unit
ALTERNATIVE NAME/S: Newton–meter of energy (symbol is J).
DETAILS: The joule (J), named after English physicist James P. Joule,* is a measure of energy. It is the energy (force) needed to move an object a distance of one meter (equal to a little more than a yard, or about 39-1/3 inches). A joule can also be defined as: “One unit of mechanical energy or work in the mks system of units, equal to the work done by a force of one newton which is applied to move an object one meter in the direction of the force.”
In 1902 an Italian, Giovanni Giorgi, proposed “mks” unit as one of the four base units of electrical standards. These four were the meter, kilogram, second, and ampere. The mks is defined in terms of the force of attraction between two parallel electrical current-carrying conductors.
The cgs system had been declared official in 1881, at the first International Electrical Congress. The erg was adopted as its unit of energy in 1882. Wilhelm Siemens, in his inauguration speech as chairman of the British Association for the Advancement of Science (23 August 1882) first proposed the Joule as unit of heat, to be derived from the electromagnetic units Ampere and Ohm, in cgs units equivalent to 107 erg. The naming of the unit in honour of James Prescott Joule (1818–1889), at the time retired but still living (aged 63), is due to Siemens:
"Such a heat unit, if found acceptable, might with great propriety, I think, be called the Joule, after the man who has done so much to develop the dynamical theory of heat."[10]
At the second International Electrical Congress, on 31 August 1889, the joule was officially adopted alongside the watt and the quadrant (later renamed to henry).[11] Joule died in the same year, on 11 October 1889. At the fourth congress (1893), the "international ampere" and "international ohm" were defined, with slight changes in the specifications for their measurement, with the "international joule" being the unit derived from them.[12]
One unit of work or energy is equal to about 1.00017 absolute joules. The United States and International Joule are the same.
ONELINER: The joule is the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre
OTHER CONNECTIONS: si units
BIBLIOGRAPHY:
“Electrical Units and Standards”. McGraw-Hill Encyclopedia of Science and Technology. 9th ed. V.19. San Francisco: McGraw-Hill. 2002.
Gove, Philip Babcock, PhD ed.“Joule.” Webster’s 3rdNew International Dictionary of the English Language, Unabridged. Springfield, Mass.:Merriam-Webster Inc., 1993.
Myers, Robert A. ed. “Electricity.” Encyclopedia of Physical Science and Technology. V. 4. San Diego, Calif: Academic Press, 1987.
Parker, Sybil P., ed. “Joule.” McGraw-Hill Dictionary of Scientific Terms, 4thEdit. San Francisco: McGraw-Hill Book Co, 1989.
Weisstein, Eric W. “Joule, James P.” Science World of Wolfram. 13 Dec 2003.
http://scienceworld.wolfram.com/biography/Joule.html.