There is probably no person who does not know the name James Joule. The discoveries of this physicist are applied all over the world. Which path did the scientist go? What discoveries did he make?
Life of an outstanding physicist
December 24, 1818 was born James Joule. The biography of the future physicist begins in the English town of Salford, in the family of the successful owner of the brewery. The boy was trained at home, for some time John Dalton taught physics and chemistry . Thanks to him, the English physicist fell in love with science.
Joule did not have good health, he spent a lot of time at home, conducting physical experiments and experiments. Already at the age of 15, due to his father’s illness, he had to manage the brewery with his brother. Work at his father’s factory did not allow him to go to university, so James Joule devoted himself entirely to his home laboratory.
From 1838 to 1847, a physicist actively studied electricity and made his first scientific successes. 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, Joule concludes the first and only marriage with Amelia Grimes. Soon they are born Alice Amelia and Benjamin Arthur. In 1854, the wife and son die. Joule himself dies in 1889 in England, in the city of Sale.
Over the course of his life, he has published about 97 works on physics, some of them written together with other scientists: Lyon, Thomson, etc. For outstanding scientific achievements and open laws of physics, he was awarded several medals and received a lifetime pension from the UK government in the amount of about 200 pounds.
First works and experiments
Watching the steam engines at his father's brewery, James Joule decided to replace them with electric ones to work efficiently. In 1838, he published an article in a scientific journal, in which he painted the device of an electromagnetic motor invented by him. In 1840, new electric motors appeared at the brewery, and the physicist continued to study electric current and heat generation. It later turned out that steam engines were much more efficient.
During the experiments, Joule creates thermometers that are capable of measuring temperature with an accuracy of 1/200 degree. This allows him to delve into the study of the thermal effect of current. In 1840, thanks to further observations, the physicist discovers the effect of magnetic saturation. In the same year he sent to the Royal Scientific Society the work "On the formation of heat by electric current." The article was not rated. Only the Manchester literary and philosophical magazine agreed to publish it.
Joule-Lenz Law
Unrecognized by the London scientific community, the article subsequently proved to be one of the main achievements of the scientist. In the article, James Joule talked about the relationship between the current strength and the amount of heat released. He argued 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 time the current passes.
At this time, a similar theory was developed by Emilius Lenz. The fact that the conductivity of a metal conductor depends on temperature, the Russian physicist discovered back in 1832. To accurately determine the temperature in the conductor, the scientist invented a special vessel in which alcohol was poured. The wire through which the current passed was lowered into the vessel. It was further monitored for how long the alcohol warmed up. Joel James Prescott used a similar method, only used water as a liquid.
Lenz published the results of many years of research only in 1843, but in his works there were more accurate scientific justifications than in Joule, whose work at first they did not even want to print. Given the primacy of the Joule and the exact calculations of Emilia Lenz, it was decided to name the law in honor of both. Over time, the Joule-Lenz law laid the foundation for thermodynamics.
Magnetostriction
In parallel with the properties of electric current, James Joule studies magnetic phenomena. In 1842, he notes that iron changes in size under the influence of magnetic waves. If metal rods are placed in a magnetic field, their length will be a little longer.
The scientific community doubted the existence of any discovery here. 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 which he received clear evidence.
Later it turned out that other metals also have this effect, and the phenomenon itself was called magnetostriction. Now for the discovery of the Joule have found many ways to use. For example, magnetostrictive metals are used as waveguide material for measuring the water level in tanks. This phenomenon is also used for the manufacture of tags in anti-theft systems.
Gas experiments
In the 40s, James Joule actively studied the properties of gas, namely the phenomena associated with its expansion and contraction. He conducted an experiment with the expansion of a discharged gas, while proving that its internal energy was independent of volume. Only the gas temperature is important.
In 1848, for the first time in the history of physics , Joule measured the speed of gas molecules. This experience was an early work on the kinetic theory of gases, giving impetus to further research in this area. The work of Joule was later continued by the Scot James Maxwell.
For a significant scientific contribution in honor of an English physicist, the unit of measurement of work, the amount of heat and energy was named Joule.
Joule and thomson
Huge impact on the activities of Joule and his recognition in the scientific world had William Thomson. Scientists met in 1847 when Joule presented a report to the British Association of Scientists on measuring the mechanical equivalent of heat.
Until Thomson, the Joule was not taken seriously in academia. Who knows, maybe we would not have discovered the laws of physics that he discovered if William Thomas had not explained their importance to the “snobs” of the British community.
Together, physicists studied the properties of gases, discovering that with adiabatic throttling the gas cools. That is, the temperature of the gas (or liquid) decreases while passing through the throttle (insulated valve). The phenomenon is called the Joule-Thomson effect. Now this phenomenon is used to obtain low temperatures.
Scientists also studied the thermodynamic scale, named after the title of Lord Kelvin, which belonged to William Thomson.
Confession of James Joule
Fame and recognition nevertheless overtook the English physicist. In the 50s 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, Joule became president of the British Science Association. He was awarded the degrees of Doctor of Law at Dublin College, University of Edinburgh and Oxford.
In his honor, a statue was installed in the city hall in Manchester and a memorial in Westminster Abbey. On the far side of the moon there is a crater of James Joule.
Conclusion
A famous scientist named after the laws of physics and units of measurement might not have achieved recognition. Thanks to his perseverance and work, he did not stop at numerous failures. In the end, he proved the right to his place in the sun, or at least on a lunar crater.