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 inter- convertible. 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=I 2 R.), 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 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.

    joule joule  +Joule +Joule 

Done by: Liaw Wan Qing (6), Lorraine Lim Wen Jing (8), Wee Yu Xuan (21)