James Prescott Joule(Eng. James Prescott Joule; December 24, 1818, Salford, Lancashire, England, UK - October 11, 1889, Sale, Cheshire, England, UK) - English physicist, who made a significant contribution to the development of thermodynamics. He substantiated the law of conservation of energy on experiments. Established the law that determines the thermal effect of electric current. He calculated the speed of movement of gas molecules and established its dependence on temperature.

He experimentally and theoretically studied the nature of heat and discovered its connection with mechanical work, as a result, almost simultaneously with Mayer, he came to the concept of universal conservation of energy, which, in turn, provided the formulation of the first law of thermodynamics. He worked with Thomson on the absolute temperature scale, described the phenomenon of magnetostriction, discovered the relationship between the current flowing through a conductor with a certain resistance and the amount of heat released at the same time (the Joule-Lenz law). Made a significant contribution to technology physical experiment, improved the design of many measuring instruments.

The unit of measure for energy, the joule, is named after the Joule.

Biography

Born in the family of a wealthy owner of a brewery in Salford near Manchester, received home education, moreover, for several years his teacher in elementary mathematics, the beginnings of chemistry and physics was Dalton. From 1833 (from the age of 15) he worked at a brewery, and, in parallel with education (up to 16 years old) and science, until 1854 he participated in the management of the enterprise, until it was sold.

First experimental studies started already in 1837, interested in the possibility of replacing steam engines in a brewery with electric ones. In 1838, on the recommendation of one of his teachers, John Davies, whose close friend was the inventor of the electric motor Sturgeon, published the first work on electricity in the scientific journal Annals of Electricity, organized the year before by Sturgeon, the work was devoted to the device of an electromagnetic engine . In 1840, he discovered the effect of magnetic saturation during the magnetization of ferromagnets, and during the years 1840-1845 he experimentally studied electromagnetic phenomena.

Seeking better ways measurements electric currents, James Joule in 1841 discovered the law named after him, establishing a quadratic relationship between the strength of the current and the amount of heat released by this current in the conductor (in Russian literature it appears as the Joule-Lenz law, since in 1842 this law was independently discovered Russian physicist Lenz). The discovery was not appreciated by the Royal Society of London, and the work was only published in the periodical journal of the Manchester Literary and Philosophical Society.

Sturgeon moved to Manchester in 1840 and headed the Gallery. practical knowledge Royal Victoria Gallery for the Encouragement of Practical Science) is a commercial exhibition and educational institution, where in 1841 Joule was invited as the first lecturer.

In the works of the early 1840s, he investigated the issue of the economic feasibility of electromagnetic motors, at first believing that electromagnets could be a source of an unlimited amount of mechanical work, but soon became convinced that from a practical point of view steam engines were more efficient at the time, publishing in 1841 the findings that the efficiency of an "ideal" electromagnetic engine per pound of zinc (used in accumulators) was only 20% of that of a steam engine per pound of coal burned, without hiding the disappointment.

In 1842, he discovers and describes the phenomenon of magnetostriction, which consists in a change in the size and volume of a body with a change in its state of magnetization. In 1843, he formulates and publishes the final results of the work on the study of heat release in conductors, in particular, experimentally shows that the heat released is in no way taken from the environment, which irrevocably refuted the theory of caloric, the supporters of which still remained at that time. In the same year I became interested common problem quantitative ratio between various forces, leading to the release of heat, and, having come to the conclusion of the existence of a certain relationship between work and the amount of heat predicted by Mayer (1842), seeks numerical ratio between these values ​​is the mechanical equivalent of heat. During the years 1843-1850, he conducts a series of experiments, continuously improving the experimental technique and each time confirming the principle of conservation of energy with quantitative results.

James Prescott Joule is an outstanding English physicist. He thoroughly studied the nature of thermal energy and discovered its connection with electric currentpassing through a conductor. He discovered many laws, and in particular the first law of thermodynamics. In honor of the scientist, the unit for measuring the amount of heat generated is named Joule. The great scientist also made an invaluable contribution to practical use electricity. He carried out work to modernize and improve the characteristics of electric motors and magnets.

James Prescott Joule was born on December 24, 1818 in the family of a wealthy brewery owner. Thanks to good financial position James family until the age of 15 was educated at home in hometown Salford. This was also facilitated by the health problems of the future scientist. After such a school, where by the way he got enough good knowledge in mathematics, physics and chemistry, naturally James wanted to continue his education. However, due to his father's illness, for some time he was forced to manage the family brewery with his older brother.

At home, James organized a physics laboratory and began to make experiments. Conducting research on the operation of the first electric motors, the scientist discovered that the power of electric machines is proportional to the product of current and voltage.

Since 1847, for seven years, the scientist has been conducting experiments to study thermal action electric current passing through a conductor. The result of his work was proportional dependence the amount of heat generated in the conductor, the resistance of the material itself, and the square of the current flowing through it.

James Prescott Joule, working with William Thomson, essentially became the progenitor of all refrigerators and refrigeration units. He proved that the expansion of a gas without performing work leads to a significant decrease in its temperature. This effect was named after both scientists - the Joule-Thomson effect.

In 1850, the scientist was elected a full member of the British Royal Society. And in 1961, his contemporaries already named the unit of work and energy in the name of the scientist. international system SI. This is only a tiny part of the contribution of the scientist, relating directly to the study and development of electricity. His participation in the formation of all science, including modern science, is simply invaluable.

James Joule - Pretty famous person. We all know this name since school lessons physics. However, then no one delved into his biography and achievements, and yet his life path very interesting. In the article we will consider detailed biography scientist, and also talk about what he achieved.

Childhood

James Joule, whose biography we are considering, was born in 1818, on December 24. The boy was born into a wealthy family of the owner of a brewery located in Salford. James was educated at home. His first teacher in the principles of physics, chemistry and elementary mathematics was Dalton. From the age of 15, the boy worked at his father's factory and took direct involvement in their management. He combined this activity with training during the year.

First studies

When did James Joule become interested in science? A brief biography of the guy tells that he began to conduct his first research in 1837. Then he was very interested in the issue of replacing steam engines with electric ones at his father's brewery. A year later, the young man published his first work on electricity in one of scientific journals. He was advised to do this by his teacher John Davis, who, by the way, was a close friend of Sturgeon, who invented the electric motor. The magazine in which James Joule was published was also owned by Sturgeon. In 1840, a young researcher noticed the effect of magnetic saturation when magnetizing ferromagnets. From that moment until 1845, he actively studied electromagnetic phenomena experimentally.

Joule's law

What does Joel James Prescott do next? The brief biography of the man continues with the fact that in 1841 he discovers the law of the quadratic relationship between the strength of the current and the heat that is released. Later, the law received his name, but we know it as the Joule-Lenz law, because in 1842 it was discovered by a physicist German descent from Russia by Emil Lenz. The discovery of the scientist was not appreciated at its true worth. The Royal Society of London ignored him, and the work itself was published in a modest periodical.

Work as a lecturer

But who did James Joule work for? Interesting Facts about this man is rare, but it is known that he was a lecturer. Already known to us, Sturgeon moved to Manchester and opened the Gallery of Practical Knowledge there, where he invited Joule to take the place of a lecturer. Surprisingly, some of the students were taught by James Joule himself!

In his research of that time, the scientist spent a lot of time on the issue of the economic benefits of electromagnetic motors. At first he believed that electromagnets had great potential, but soon he was personally convinced that steam engines were much more efficient. Joule published the results of this study, not hiding his own disappointment.

The scientist's discoveries happened very quickly. Already in 1842, he describes magnetostriction, which consists in the fact that bodies change their sizes and volumes when varying degrees magnetization. A year later, he completes research on heat generation in conductors and publishes his results. They consisted in the fact that the heat generated is not taken from outside. This completely refuted the theory of caloric, the adherents of which still existed at that time.

In the period from 1843 to 1850, a man is engaged in a series of studies, improving his technique and confirming by many experiments the correctness of the principle of conservation of energy.

A family

In 1844, the Joules change their place of residence. At the new place, the man meets his future wife, Amelia Grimes. In 1847, the couple married, and they had a daughter and a son. At the same time, in the house, Joule equips himself with a convenient laboratory for experiments. However, his happiness did not last long, because in 1854 his beloved wife died.

General description of studies

By the end of the 1840s, the work of the hero of our article was universally recognized. In 1847, the scientist meets Thomson, who highly appreciates Joule's experimental technique. Then scientists begin to cooperate. Thomson's ideas about molecular kinetic theory were formed largely under the influence of James's ideas. Together, scientists create a thermodynamic temperature scale.

It seems that James Joule and his discoveries do not age, because already a year later he proposes to use the gas model to analyze the occurrence of thermal effects with increasing pressure. The Joule gas model consisted of elastic balls of microscopic size, which created pressure when they touched the walls of the vessel. The scientist's research was published in the Philosophical Transactions of the Royal Society on the advice of German physicist Clausius. This work has provided a huge impact on the formation and development of thermodynamics, despite the fact that many errors were found later in Joule's research. In addition, the experiments are similar to those conducted by van der Waals in the 1870s to simulate a real gas.

In 1850, a man becomes a member of the Royal Society of London. In studies carried out in 1851, which concern the creation theoretical model heat as the movement of small elastic particles, the scientist very accurately calculated the heat capacity for some gases. A year later, together with his old friend Thomson, he describes the phenomenon of a change in gas temperature during adiabatic throttling. Later this effect was called Joule-Thomson. Moreover, this discovery contributed to the emergence of a new branch of natural science - low temperature physics.

In the 1850s, the researcher published a whole series of articles on electrical measurements. Despite the possibility of using modern designs, James Joule was confident that only through experiment can the most accurate results be obtained.

In 1859, a scientist is engaged in research thermodynamic properties solids. Detects non-standard properties of rubber in comparison with other materials. A year later, mirages, atmospheric thunderstorms and meteorites fall into the scope of his interests, which he tries to explain with scientific point vision.

Heat equivalent

Since 1843, the scientist has been searching for the mechanical equivalent of heat. Through experiments, he manages to show that a certain amount of heat can be converted into a certain amount mechanical force. In the same year, he publishes the results of research, and a year later he formulates the law of heat capacity for crystalline bodies, which is known as the Joule-Kopp law. However, the exact wording experimental confirmation Joule introduced his law only in 1864.

After that Joule James Prescott, short biography which is described above, devotes himself to the study of heat generation when a liquid is passed through narrow tubes. In the period from 1847 to 1850, he manages to derive the most accurate mechanical equivalent of heat. He uses a metal calorimeter that he sets up on a wooden bench. In this experiment, he investigated the amount of heat that is released during rotation due to axis friction. Some of the scientist's estimates are very close to exact values that were found in the last century.

The struggle for authorship

In the 1840s, a serious discussion began in the print media about who was the discoverer of the law of conservation of energy between Mayer and Joule. In fact, Mayer published his work earlier, but no one took it seriously, since he himself was a doctor by profession. James Joule's law found great support, because at that time such scientists as Stokes, Faraday and Thomson supported his candidacy. Some openly supported Mayer, emphasizing that he was the first to make the discovery, while others defended the right to authorship of Joule. In the end, priority of authorship was left to Mayer.

Memory

Physicist James Prescott Joule is awarded the King's Medal. In 1860 he became president of the Manchester Literary and Philosophical Society. In addition, he holds an LL.D. from Trinity College Dublin, a LL.D. from the University of Edinburgh, and a Ph.D. civil law in Oxford University. In 1866 he received the Copley medal, and in 1880 he became the owner of the Albert medal. After 8 years, the government awarded him a lifetime pension. Joule served twice as President of the British Scientific Association.

In 1889, a unit for measuring the amount of heat, energy, and work was named after him. There is a monument to the scientist in Manchester City Hall, which is located opposite the monument to Dalton.

James Prescott Joule($1818$ - $1889$) - English physicist who made a significant contribution to the development of thermodynamics.

Biography

Remark 1

He was the son of Benjamin Joule, owner of a relatively large brewery.
James Joule received his initial education from private tutors, mainly because of his bad condition health. He had problems with his spine, but over time his condition improved, but throughout his life the scientist remained hunched over, this was reflected in his character and contributed to his shyness.

From $1834$ he studied with John Dalton in Manchester at the Literary and Philosophical Society. Like Dalton, Joule was a strong supporter of the atomic theory, while many scientists in this period were still skeptical of it.

In later years, James Joule studied with John Davis and became interested in electricity, he and his brother experimented, striking electric shock, each other and family servants.

Remark 2

Scientific achievements

Electricity

Remark 3

Science was originally a hobby for Joule, but even while working in a brewery, he began to explore possibilities for replacing boilers with the newly invented electric motor.

Driven in part by a desire to appreciate economic consequences such a replacement, it focuses on measurements that can be used to determine which energy source is more efficient. Thus, in $1841$, he discovered Joule's law, in which the heat released by the direct action of any galvanic current is proportional to the square of the current, multiplied by the resistance of the conductor. (The derived unit of energy or work, the Joule, was named after him.) Joule concluded that burning a pound of coal would be more economical than wasting precious pounds of zinc for an electric battery.

Joel attempts to present the results to the Royal Society, but is mistaken there for a provincial dilettante.

In $1843$, Joule calculated the amount of mechanical work needed to produce an equivalent amount of heat. This quantity has been called the "mechanical equivalent of heat". Again he presented a report on his findings, this time to the British Association for the Advancement of Science. Again, the response was unenthusiastic. Several leading journals also refused to publish papers on Joule's work.

Joule's work on the relationship between heat, electricity, and mechanical work was largely ignored until $1847. Only William Thomson recognized that Joule's work fit into a unifying pattern that was already beginning to emerge in physics, and he enthusiastically approved of Joule's work.

In $1849$ Joule delivered his paper entitled "On the Mechanical Equivalent of Heat" to the Royal Society, Faraday acting as his sponsor. The following year, the Royal Society published Joule's paper.