James Joule: biography, scientific discoveries

Probably, there is no person who does not know the name James Joule. The discoveries of this physicist are used all over the world. What was the path of the scientist? What discoveries did he make?

The life of an outstanding physicist

On December 24, 1818, James Joule was born. Biography of the future physics begins in the English town of Salford, in the family of a successful owner of the brewery. The boy's training took place at home, for some time he was taught physics and chemistry by John Dalton. Thanks to him, an English physicist loved science.

Joule did not have good health, he spent a lot of time at home, doing physical experiments and experiments. Already at 15, because of his father's illness, he had to manage the brewery with his brother. Working at his father's factory did not give him the opportunity to enter the university, so James Joule was entirely devoted to the home laboratory.

From 1838 to 1847, the physicist was actively studying electricity and making his first scientific achievements. In the journal Annals of Electricity he publishes an article on electricity, and in 1841 he opens a new physical law, which now bears his name.

In 1847, Joel concludes the first and only marriage with Amelia Grimes. Soon they are born Alice Amelia and Benjamin Arthur. In 1854, the wife and son were killed. Joule himself dies in 1889 in England, in the city of Sale.

In his lifetime, he published about 97 papers on physics, some of them written jointly with other scientists: Lion, Thomson, etc. For outstanding scientific achievements and open physics laws, he was awarded several medals and received a lifetime pension from the UK government in the amount of About 200 pounds.

The first works and experiments

Watching the steam engines at his father's brewery, James Joule decided to replace them with electrical ones for performance. In 1838, he published in an academic journal an article in which he described the device of the electromagnetic engine he invented. In 1840 new electric motors appeared on the brewery, and the physicist continued studying the electric current and the release of heat. Later it turned out that the steam engines were much more efficient.

During the experiments, Joule creates thermometers that are able to measure the temperature with an accuracy of 1/200 degrees. This allows him to go deeper into the study of the thermal effect of the current. In 1840, thanks to further observations, the physicist discovers the effect of magnetic saturation. In the same year he sends to the Royal Scientific Society the work "On the formation of heat by electric current." The article was not appreciated. Only Manchester's literary and philosophical journal agreed to publish it.

Law of Joule-Lenz

Unrecognized by the London Scientific Society, the article later turned out to be one of the main achievements of the scientist. In the article, James Joule spoke of the relationship between the strength of the current and the amount of heat released. He claimed that the amount of heat that is released in the conductor is directly proportional to the resistance of the conductor, the square of the force and the time of passage of the current.

At this time, a similar theory was developed by Emilie Lenz. The fact that the conductivity of the metallic conductor depends on temperature, the Russian physicist discovered as early as 1832. To accurately determine the temperature in the conductor, the scientist invented a special vessel into which alcohol was poured. The wire through which the current was passed was lowered into the vessel. Then it was monitored for how long the alcohol would heat up. Joel James Prescott used a similar method, only used water as a liquid.

The results of years of research Lenz published only in 1843, but in his writings there were more accurate scientific justifications than Joule, whose work at first did not even want to print. Given the primacy of Joule and the exact calculations of Emilie Lenz, it was decided to name the law in honor of both. Over time, the Joule-Lentz law marked the beginning of thermodynamics.

Magnetostriction

In parallel with the electric current properties, James Joule studies magnetic phenomena. In 1842 he notes that iron varies in size under the influence of magnetic waves. If the metal rods are placed in a magnetic field, their length will become slightly larger.

The scientific community doubted the existence of any discovery. The change in the size of the rods was so insignificant that the human eye did not catch it. But the physicist developed a special technique, with the help of which he obtained evident evidence.

Later it was found out that other metals possess this effect, and the phenomenon itself was called magnetostriction. Now for the discovery of Joule found many ways to use. For example, magnetostrictive metals serve as the material of the waveguide for measuring the water level in reservoirs. This phenomenon is also used for making marks in anti-theft systems.

Experiments with gas

In the 1940s, James Joule was actively studying the properties of gas, namely, the phenomena associated with its expansion and contraction. He experimented with the expansion of a discharged gas, proving that his internal energy does not depend on volume. Only the temperature of the gas is important.

In 1848, for the first time in the history of physics , Joule measured the velocity of gas molecules. This experience became an early work on the kinetic theory of gases, giving impetus to further research in this field. The work of Joule was later continued by the Scotsman James Maxwell.

For a significant scientific contribution in honor of the English physicist, the unit of measurement of work, quantity of heat and energy - Joule was named.

Joule and Thomson

A huge influence on the activities of Joule and his recognition in the scientific world was made by William Thomson. Scientists met in 1847, when Joule presented to the British Association of Scientists a report on measurements of the mechanical equivalent of heat.

Until Thomson Joule was not taken seriously in the scientific community. Who knows, maybe we would not have learned the laws of physics discovered by him, if William Thomas had not explained their importance to the "snobs" of the British community.

Together, physicists have studied the properties of gases, discovering that with adiabatic throttling the gas cools. That is, the temperature of the gas (or liquid) decreases during passage through the throttle (an isolated valve). The phenomenon was called the Joule-Thomson effect. Now this phenomenon is used to obtain low temperatures.

Scientists also dealt with the thermodynamic scale, named after the title of Lord Kelvin, which belonged to William Thomson.

Recognition of James Joule

Glory and recognition still caught up with the English physicist. In the fifties of the XIX century, he became a member of the Royal Society of London and was awarded the Royal Medal. In 1866, he received the Copley medal, and then the Albert medal.

Several times Joel became president of the British Scientific Association. He was awarded academic degrees of doctor of law at Dublin College, Edinburgh and Oxford universities.

In his honor there is a statue in the Municipal Building in Manchester and a memorial in Westminster Abbey. On the other side of the Moon there is a crater of James Joule.

Conclusion

The famous scientist, whose name is called the laws of physics and units of measurement, could not achieve recognition. Thanks to his perseverance and hard work, he did not stop at numerous failures. In the end, he proved the right to his place under the sun or at least on the lunar crater.