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Joule studied the nature of heat, and discovered its relationship to mechanical work (see energy). This led to the theory of conservation of energy (the First Law of Thermodynamics). The SI unit of work, the joule, is named after him, and is pronounced to rhyme with "fool." He worked with Lord Kelvin to develop the absolute scale of temperatureTemperature is the physical property of a system which underlies the common notions of "hot" and "cold"; the material with the higher temperature is said to be hotter. General description The formal properties of temperature are studied in thermodynamics., made observations on magnetostrictionMagnetostriction is a property of ferromagnetic materials to undergo a change of their physical dimensions when subjected to a magnetic field. This effect was first identified in 1842 by James Joule when observing a sample of nickel. This property, which, and found the relationship between the flow of current through a resistanceAn ideal resistor is a component with an electrical resistance that remains constant regardless of the applied voltage or current flowing through the device. While "real world" resistors cannot attain this perfect goal, they are designed to present little and the heat dissipated, now called Joule's lawJoule's law (due to James Prescott Joule) expresses the amount of heat generated by an electrical resistor, and is expressed by the relation : by current flowing through a resistor with resistance for a time , and is the heat generated or : where is the c.
James Prescott Joules was the son of a brewer, he was tought a by the famous scientist John DaltonJohn Dalton ( September 6, 1766 July 27, 1844) was a British chemist and physicist, born at Eaglesfield, near Cockermouth in Cumberland. He is most well known for his advocacy of the atomic theory. Biography Early years His father, Joseph Dalton, was a we. He had always been interestied in electricity .James ran the his brewery as an adult, and science was just a hobby. His work on energylead up to his attempt to build an electric motor that would replace steam engines.
Joule's ideas about energy were not accepted at first, partly because they depended on extremely precise measurementMeasurement is the determination of the size or magnitude of something. Measurement is not limited to physical quantities, but can extend to quantifying almost anything imaginable. Examples of measurement range from, degrees of uncertainty, to the consumes, which had not previously been common in physics. His best-known experiment involved the use of a falling weight to spin a paddlewheel in an insulated barrel of water, whose increased temperature he measured. He claimed to be able to measure temperatures to an accuracy of 1/200 of a degree Fahrenheit, which his contemporaries did not believe possible. Joule's experiments complemented the theoretical work of Rudolf Clausius, who is considered by some to be the coinventor of the energy concept.
Further resistance came because Joule's work contradicted the widespread belief that heat was a fluid, the "caloric", that could be neither created nor destroyed, whereas Joule claimed that heat was only one of many forms of energy, and only the sum of all the forms was conserved.
Joule was proposing a kinetic theory of heat (he believed it to be a form of rotational, rather then translational, kinetic energy), and this required a conceptual leap: if heat was a form of molecular motion, why didn't the motion of the molecules gradually die out? Joule's ideas required one to believe that the collisions of molecules were perfectly elastic. We should also remember that the very existence of atoms and molecules was not widely accepted for another hundred years.
Although it may be hard today to understand the allure of the caloric theory, at the time it seemed to have some clear advantages. Carnot's successful theory of heat engines had also been based on the caloric assumption, and only later was it proved by Lord Kelvin that Carnot's mathematics were equally valid without assuming a caloric fluid.
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