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(1818 - 1889) 
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James Joule was born in Salford, England in 1818. He was a physicist who is credited with discovering the law of conservation of energy that states energy cannot be created or destroyed, but rather, only changed in its form. Two other German scientists, Hermann von Helmholtz and Julius von Mayer are also credited with this discovery. In 1840, Joule discovered that heat is produced in any electrical conductor and today this is known as Joule's Law. Joule also worked with William Thompson and found that the temperature of a gas falls when it expands without doing any work. This idea led eventually to the principle behind today's refrigeration and air-conditioning systems. Joule's name is used to describe the international unit of energy known as the joule. |