We are all familiar that the unit of energy is Joule and this is named after an English physicist James Prescott Joule. He studied the nature of heat and discovered its relationship to mechanical work. This laid the foundation for the first law of thermodynamics which is the law of conservation of energy.

James Prescott Joule was born on 24th December 1818 in Salford, Lancashire. Joule belonged to a well to do family, his father Benjamin Joule was a wealthy brewer and his mother Alice Prescott was the daughter of John Prescott of Wigan. Benjamin and Alice had five children and Joule was one of them. Joule was a very sensitive and frail child therefore he was not able attend school and was homeschooled. The famous scientist John Dalton taught him arithmetic and geometry. The works of Manchester engineers Eaton Hodgkinson and Peter Ewart and the chemist William Henry had a strong influence on Joule. He and his brother were very fond of electricity, they did experiments by giving electric shocks to each other and also to the servants at home. In one of his experiments he rashly shocked and knocked out one of his servants.

At the age of 15 Joule was forced to manage the brewery along with his elder brother since their fathers health declined. Alongside, Joule received his education from famous English physicist John Dalton.

At the age of nineteen Joule constructed an electromagnetic engine. Joule wanted to improve his brewery machinery for achieving higher efficiency. Therefore, in the year 1840, he worked on replacing the steam engines in his brewery system with newly invented electric motor. In the year 1841, Joule designed an experiment to establish relationship between resistance, heat and current in a conductor. This relationship is called as Joule’s first law.

In the year 1845, He described about the paddle wheel experiment which helped him understand the law of conservation of energy. In this experiment he proposed that mechanical energy was converted into heat energy. His efforts laid the base for the law of conservation of energy which is the first law of thermodynamics. He worked along with Lord Kelvin on formulation of the absolute scale of temperature. He carried out great research work on Magnetostriction, which is the property of ferromagnetic materials to change their shapes when exposed to a magnetic field. This property was first discovered by Joule in the year 1842 while performing an experiment with nickel. Joule was given the credit for the first ever calculation on the velocity of a gas molecule.

In the year 1852, he received the Royal Medal of the Royal society for the paper he published on the Mechanical Equivalent of Heat. He became the president of Manchester Literary and Philosophical Society in the year 1860. Joule’s served as the president of British Association for the Advancement of Science from 1872 to 1887. For his work on establishing a relationship between electrcity, heat and mechanical work, he received the Albert Medal of the Royal Society of Arts in the year 1880. A statue of Joule stands in the Manchester Town Hall in his comemoration.

Joule married Amelia Grimes in the year 1847. She was the daughter of Mr. John Grimes, who was an administrator of customs, Liverpool. The couple had two children, Benjamin Arthur and Alice Amelia. His wife and son passed away in an unfortunate accident in the year 1854. He lived as a widower through the rest of his life. For his lifetime work and acheivements, the British government granted him two hundred pound sterling as pension. Joule suffered from prolonged illness and died on October 11th, 1889 in Sale , England. He was 70 when he passed away.

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