Physics

James Prescott Joule


James Prescott Joule (1818 - 1889) was born in December 1818 in Salford, England. He was the son of a leading Manchester brewer, and always expressed an interest in machines and physics. Joule had contact with great physicists like John Dalton who taught him science and math.

Joule studied the nature of electric current. After numerous experiments, he found that when a conductor is heated when a current flows through it, a transformation of electrical energy into thermal energy occurs. This phenomenon is known as the Joule Effect (which names the blog) in his honor.

Interested in the study of heat, Joule also conducted several experiments in this area, which helped him to determine a relationship for the equivalence between mechanical work and heat. Which helped in the formulation of the theory of energy conservation (First Law of Thermodynamics), a contribution that drove the study of thermodynamics.

He worked with Physicist William Thomson (Lord Kelvin) performing thermodynamic experiments. Together they came to the Joule-Thomson effect that relates the temperature and volume of a gas.

Science itself was undergoing several changes. One of them concerns the social responsibility of science, it was at this time that man realized that science is not just a form of knowledge organization. Another important change was regarding man's view of nature. Before science was concerned with exploring the constitution of nature, but now man has realized that he can extract energy from nature and transform it. Man begins to dominate nature's energy sources, wind, water, steam… etc. All of these changes are part of the Industrial Revolution.

The joule, which has the symbol J, is the unit of measurement of energy and work in the international system of units. James Joule's experiments and great contributions to physics brought him recognition. Joule died in October 1889 in Sale, England, and after his death, this tribute was made.

A joule can be defined as the work required to exert a force of one newton over a distance of one meter (N.m). Another definition for joule is, the work done to produce one watt of energy for one second (W.s).