When Joule was born, his family lived in New Bailey Street in salford, adjacent to his brewery. Joule has been studying at a home school in Pendl Bury near salford because of his poor health when he was young.
Joule followed his father in brewing since childhood and had no formal education. When he was young, under the introduction of others, Joule met the famous chemist Dalton. Dalton gave Joule enthusiastic teaching, taught him knowledge of mathematics, philosophy and chemistry, and laid a theoretical foundation for Joule's later research. Moreover, Dalton taught Joule the scientific research method of combining theory with practice, stimulated Joule's interest in chemistry and physics, and decided to engage in scientific research with his encouragement.
1840, his first important paper was sent to the Royal Society, in which he pointed out the relationship between the heat emitted by electrical conductors and the current intensity, conductor resistance and current-on time, which is Joule's law.
Joule put forward the law of conservation and transformation of energy: energy will neither disappear nor be generated out of thin air, but can only be transformed from one form to another, or from one object to another, while the total amount of energy remains unchanged, which laid the foundation for the first law of thermodynamics (the principle of energy immortality).
1834, Joule and his younger brother Benjamin (16 years old) were sent to study under Dalton of Manchester Literature and Philosophy Society. The Joule brothers studied arithmetic and geometry with Dalton for two years. Later Dalton retired due to a stroke. But this experience with Dalton influenced Joule's life. Joule was later directed by john davis (lecturer). The Joule brothers are crazy about electricity. They have tested each other with electric shocks and domestic servants.
Joule entered the University of Manchester on 1835 under the guidance of Dalton. After graduation, he started to run his own brewery, and his business was very active until 1854 sold the brewery. Science was just a hobby of Joule at first, until later he began to study the feasibility of replacing the steam engine of brewery with the newly invented motor.
1838, his first scientific paper on electricity was published in the yearbook of electricity. This academic journal was founded and presided over by Davis' colleague William sturgeon.
1840, he came up with the formula of Joule's law, which was intended to surprise the Royal Society, but later found himself only regarded as an amateur in the countryside. 1840 When sturgeon moved to Manchester, he and Joule became the intellectual core of the city. They agree that science and theology should and may merge. Joule began to give lectures at the Royal Victorian Gallery of Applied Science in sturgeon.
He later realized that the heat generated by the steam engine burning 65,438+0 pounds of coal was five times that generated by the Grove battery (the early battery) consuming 65,438+0 pounds of zinc. Joule's usual "economic load" standard is to increase the capacity of 1 foot from 1 pound, that is, foot-pound (English: foot-pound).
Influenced by Franz Aepinus's thought, Joule tried to explain electricity and magnetism with atoms surrounded by "thermal ether in a vibrating state".
However, Joule's interest shifted from a narrow economic problem, that is, how much work can be extracted from a given source, to thinking about the transferability of energy.
In 1883, he published some experimental results. The results show that the thermal effect he quantified in 184 1 is due to the heat of the conductor itself, not the heat from other parts of the device. This conclusion is a direct challenge to the heat theory at that time. According to the heat theory, heat can neither be created nor destroyed. Since lavoisier put forward the heat theory in 1783, the heat theory has been the dominant theory in the field of heat. Lavoisier's influence, coupled with the success of Nikolai Cano's theory of heat engine and heat mass in practice since 1824, makes Joule, who is neither in academia nor engineering, look bumpy in the future. Supporters of heat theory are prepared to point out that the symmetry of thermoelectric effect shows that thermal energy and electric energy can be transformed into each other (at least approximately) through reversible processes. 1837, Joule installed an electromagnetic machine driven by a battery and published a paper on it, which attracted people's attention.
1840, Joule put the loop coil into a test tube filled with water, and measured the water temperature at different current intensities and resistances. In February, 65438, Joule read a paper on heat generation by electric current at the Royal Society, and put forward the law of heat generation by electric current passing through a conductor. Not long after, Russian physicist Lengz discovered the same law independently, also called Joule-Lenz Law.
1843, Joule designed a new experiment. Wind a small coil around the iron core, measure the induced current with an ammeter, put the coil in a container filled with water, measure the water temperature and calculate the heat. This circuit is completely closed and there is no external power supply. The increase of water temperature is only the result of the conversion of mechanical energy into electrical energy and electrical energy into thermal energy, and there is no heat and mass transfer in the whole process. This experimental result completely negates the heat theory.
On August 2 1843 and 2 1 day, Joule reported his paper "On the Thermal Effect of Electromagnetic and the Mechanical Value of Heat". In his paper, he said that the heat of 1 kcal was equivalent to 460kg·m of work, and his report was not supported and strongly responded. Later, he realized that more accurate experiments were needed.
1844 Joule studied the temperature change of air in the process of expansion and compression, and he made many achievements in this respect. Joule calculated the thermal velocity of gas molecules by studying the relationship between the velocity and temperature of gas molecules, which laid the foundation of Boyle-Edm Edme Mariotte's law and Guy-Lussac's law in theory and explained the nature of gas pressure on the wall.
In 1852, they found that when the freely diffused gas enters the low-pressure container from the high-pressure container, the temperature of most gases and air will drop. This phenomenon was later called Joule-Thomson effect. This effect is widely used in low temperature and gas liquefaction. Joule also did a lot of valuable work for the development of steam engines.
1847, Joule did an experiment that is considered to be the most ingenious design idea so far: he put water in the calorimeter, installed a rotating shaft with blades in the middle, and then let the falling weight drive the blades to rotate. Due to the friction between the blades and the water, both the water and the calorimeter become hot.
According to the height of the drop hammer, the transformed mechanical work can be calculated; According to the rising temperature of water in calorimeter, the rising value of internal energy of water can be calculated. By comparing these two figures, we can get the exact value of the mechanical equivalent of heat. Joule also experimented with whale oil instead of water, and the average mechanical equivalent of heat was 423.9 kg m/kcal. Then replace water with mercury, and constantly improve the experimental method until 1878. At this time, nearly forty years have passed since he started this work, and more than 400 experiments have been carried out in various ways before and after.
When Joule published his research results again at the meeting of the British Science Society in 1847, it was still not supported. Many scientists doubt his conclusion and think that the transformation between various forms of energy is impossible. Until 1850, other scientists obtained the law of energy conservation and the law of energy transformation in different ways, and their conclusions were the same as Joule's, at which time Joule's work was recognized.
1850, Joule became a member of the Royal Society for his important contribution to physics. He was 32 years old, and two years later he won the Royal Medal. Many foreign academy of sciences also gave him high honors. Although Joule has always insisted on experimental measurement, unfortunately, his scientific creativity, especially his creativity in physical concepts, has decreased prematurely.
1875, the British Science Association entrusted him to measure the mechanical equivalent of heat more accurately. His result is 4. 15, which is very close to 1 calorie =4. 184 joules. 1875, Joule's economic situation was much worse than before. The man who used to be rich but didn't have a certain position found himself in financial difficulties. Fortunately, his friends helped him get a pension of 200 pounds a year, which enabled him to maintain a moderate but comfortable life. At the age of 55, his health deteriorated and his research work slowed down. When he was sixty years old, Joule published his last paper.
On June1889 65438+1October1day, Joule died of softening.