Volts are units of voltage. What else？ Chen Guanrong

　　introduction

　　You must be prepared to give up even the most attractive ideas immediately when experiments show that they are wrong.

　　-alessandro volta

　　Chen Guanrong | Author

　　In electricity and daily life, the international standard unit of voltage is "volt", abbreviated as "Volt", and the symbol is V. Between any two points in an electric field, if the work done by the electric field force to move 1 coulomb of positive charge from one point to another point is 1 Joule, the voltage between the two points is 1 volt. In industrial applications, kilovolts (kV), millivolts (mV) and microvolts (μV) are often used as voltage units for convenience.

　　"Volt" is the English surname of an Italian. He has a long name: Alessandro Giuseppe Antonio Anastacio Volta (February 18, 1745–March 5, 1827). Among them, Volta (Italian pronunciation: Volta) is his surname, Alessandro is his first name, and Giuseppe Antonio Anastasio is his name related to religion, grandfather and uncle or mother respectively. However, in modern times, the middle appellation of traditional Italian names is no longer important or even retained. If Volt is still alive today, his name on legal documents is probably just "Alessandro Volta".

　　Figure 1 alessandro volta (scanning portrait)

　　Volt was born into a wealthy Catholic family in Como, Lombardy, northern Italy. Como city is a scenic spot, famous for its Como Lake. Volt's father (Filippo Volta, 1692–1752) and mother (Donna Maria Maddalena Inzaghi, 1714–1782) raised six children: Giovanni, Marianna, Luigi, Gian Domenico, Alessandro and Chiara. Most of Volt's brothers and sisters were engaged in the clergy, and only he later became a scientist.

　　When Volt was a child, he was not the kind of intelligent "kid next door". He didn't speak until he was 4 years old, and his parents were worried that he was mentally retarded and didn't have much confidence in his future. But by the age of seven, Volt had caught up with other children in intelligence, and then he gradually surpassed them. Unfortunately, Volt's father died when he was 7 years old. When he was young, he and his sisters Marianna and Chiara were raised by his uncle, who was a deacon in Como Cathedral. In 1757, 12-year-old Volt attended Como Royal Theological Seminary after finishing his primary school education at home. When Volt was 15 years old, the teacher tried to persuade him to train with the clergy, but failed. Uncle also advised him to study law, which also failed. In fact, at this time, Volt had taken great interest in natural science. He especially liked electricity and was determined to become a physicist. At that time, he wrote a long poem about electricity after reading the famous book History of Electricity by the British scientist J. Joseph Priestley (1733–1804), which was praised by teachers and elders.

　　Figure 2 Volt's first academic paper

　　In 1763, at the age of 18, Volt began to correspond with Abbé J. A. Nollet (1700–1770), a famous French physicist, and talked about his analogy between electricity and gravity. Later, he wrote to Giovanni B. Beccaria (1716–1781), a professor of physics at Turin University and the most important Italian experimental physicist of that year, to discuss some electrical phenomena he understood. Beccaria's advice to him is to do more physics experiments and impress them on his mind. In 1769, Volt published his first academic paper entitled "On the Forces of Attraction of Electric Fire". This article attracted some academic attention and helped him get his first position in 1774 as a physics lecturer at the Royal Seminary of Como. The following year, he announced the invention of an electrophoresis apparatus (electrophorus) that can generate electrostatic charge endlessly. The instrument is mainly composed of a metal plate, in which a hardened resin mixture is placed. The experimenter can wipe the resin with silk cloth to make it charged, and then put another metal plate on top to make it charged. After that, the experimenter can remove the top plate to make its charge disappear, and then put it back on the resin to recharge it.And then removed it again. This process can be repeated indefinitely. At that time, this interesting electrical experiment caused a sensation, which made Volt famous, and he was promoted to professor of experimental physics by the college.

　　Volt began to study gas chemistry in 1776. He discovered and isolated methane. He designed some important experiments, such as igniting gas by electric spark in a self-designed closed container (called eudiometer). He perfected the condensation electroscope, which is a device based on electrophoresis to detect a small amount of charge. He invented a gas burning meter which can study the volume change of gas when it burns, and measured the air expansion coefficient. In addition, he also suggested that static electricity should be transmitted through insulated iron cables to transmit information. He also verified a "Volta's Law of Capacitance": the potential on a given object is directly proportional to the charge.

　　In 1779, he was invited to Pavia University to become a professor of experimental physics. He has held this position for nearly 40 years, during which he was also the dean of the college. During 1780-1790, Volt was sponsored by the government to carry out research tours in many European countries and met many important scientists at that time. Including Henry Cavendish, Benjamin Franklin, Antoine Lavoisier, Joseph Priestley, Pierre-Simon Laplace, Claude Berthollet, Joseph-Louis Lagrange and James Watt.

　　In 1782, he was elected as a foreign academician of the French Academy of Sciences, and in 1791, he was elected as an academician of the Royal Society of London.

　　In 1791, Luigi Galvani (1737–1798), Volt's good friend, a physicist and biologist, claimed that two different metals could generate electric current when they were connected with the leg muscles of a frog with skin, which caused the frog's leg to twitch. Galvani interpreted it as a new form of electricity found in living tissues and called it "animal electricity". Volt thinks that frog legs only conduct current between two metals, which is called "metal electricity". To prove his idea, Volt began to conduct similar experiments with only metals the following year. He put disks of different metals on his tongue to detect the weak current between different metal disks. He found that animal tissues were not needed to generate electricity. Volt's experimental report caused a heated debate between animal electricity followers and metal electricity advocates. That argument lasted for several years, and finally ended with the invention of the "Volt battery" in 1800, because the battery itself proved that the current was indeed produced by metal. However, the difference between Volt and galvani's scientific arguments is entirely a gentleman's dispute, which is harmless and leaves a much-told story.

　　In 1794, because of his outstanding contributions to electricity and chemistry, Volt was awarded the Copley Medal by the Royal Society of London. In the same year, 49-year-old Volt married an earl's daughter, Donna Maria Alonsa Teresa Peregrini (1764–1841). The couple raised three boys: Zanino (1795-1869), Flaminio (1796-1814) and Luigi Tobia (1798-1876). Unfortunately, the second child died of illness at the age of 18. He was once considered as a promising mathematician in the future. Volt was extremely sad. In a letter to a friend, he wrote: "I was deeply hit by this loss. I feel that there will never be another happy day. " Fortunately, the other two sons grew up to be quite promising. The third became a lawyer and the eldest even became the mayor of Como.

　　Fig. 3 Volt battery (Tempio Voltiano Museum)

　　In 1800, 55-year-old Volt completed the most outstanding invention in his life-Volt battery (also known as "Volta battery") after four years of repeated experiments. On March 20th of that year, he submitted a report to Sir Joseph Banks (1743–1820), Dean of Royal College London, announcing his invention and giving detailed instructions on building a new battery. In 1832, Volt's achievement was published in Proceedings of the Royal Society of London with a paper entitled "On the Electricity Excited by the Mere Contact of Conducting Substances of Different Kindes".

　　Unlike the capacitor "Leyden jar" designed by the physicist Pieter van Musschenbroek (1692–1761) in Leyden, the Netherlands in 1745, the volt battery is a container that can generate electricity by converting chemical energy into electrical energy. Volt battery consists of a series of silver disks and zinc disks that contact each other. A disk made of cardboard or absorbent material is placed between each pair of metal disks and soaked in salt water. The greater the number of these disks in series, the greater the electrical effect. Volt used this repeatable experiment to prove that metal batteries can generate weak but very stable electromotive force and continuous current. For the invention of the new battery, Volt thanked chemists and physicists such as William Nicholson (1753–1815), Tiberius Cavallo (1749–1809) and Abraham Bennet (1749–1799) for their early research work which inspired and influenced his experiments.

　　The invention of the Volt battery is unprecedented. It not only gave birth to Electrochemistry, but also predicted the revolution of electronics and electrification industry, and soon led to a large number of important scientific discoveries and technological creations related to electricity. For example, in 1800, William Nicholson (1753–1815) and Anthony Carlisle (1768–1840) used the current generated by batteries to decompose water into hydrogen and oxygen. In 1807, Sir Humphry Davy (1778–1829) used batteries to separate sodium and potassium from alkali. Michael Faraday (1791–1867) also made full use of batteries in his pioneering electromagnetic research.

　　In 1801, the French emperor Napoleon I (1769–1821) summoned Volt at the Institut de France, observed his demonstration, awarded him an exquisite gold medal, and made him a count of the kingdom of Lombardy, making him famous all over the world.

　　In 1815, the Austrian king appointed Volt as Professor of Philosophy (Natural Science) at Padova University.

　　Fig. 4 Volt shows Napoleon I his battery (J.-I. Charmet oil painting).

　　Volt stayed out of politics all his life and devoted himself to scientific research. However, after completing the battery development, he retired from public view and lived in Camnago, a suburb of Como, his hometown. Volt was seriously ill since 1823 and died on March 5, 1827 at the age of 82. He was buried in Camnago. To commemorate Volt, later generations built the Tempio Voltiano Museum near Como Lake, which displayed his experimental instruments and academic papers before his death. Before the introduction of the euro, Volt's portrait was printed on Italian 10,000 lira banknotes along with this museum and Volt batteries.

　　Figure 5 Italian 10,000 lira notes

　　In 1998, the European Chapter of international society of electrochemistry established the "alessandro volta Medal", which is awarded every two years to commend scholars who have made outstanding achievements in the fields of electrochemistry and solid-state physics.

　　Figure 6 alessandro volta Medal

　　Finally, there is an anecdote worth mentioning. Volt grew up in a devout Catholic family. When he was young, he studied in a missionary school. His uncle and his brothers and sisters were almost all clergy. There is no doubt that he is a Christian. However, he devoted himself to scientific research all his life. Of course, he may not be too religious. He often didn't go to church and neglected church activities, which attracted a lot of criticism behind him. To this end, Volt seems to be reluctant in his later years, but he clearly left a self-defense:

　　I don't understand how anyone can doubt my sincerity and attachment to the religion I believe in I was born and raised in Roman, Catholic and apostolic religious environment, and I have been doing confession inside and outside my heart. Although I often fail to perform all kinds of good deeds as a symbol of Catholic Christians, and I am deeply ashamed of my many sins, I am sure that because of God's forgiveness and kindness, I have never shaken my faith ... In this belief, I realize the pure gift and supernatural grace of God. However, I didn't ignore those confirmed beliefs and overturn personal behaviors such as doubts sometimes. I have carefully studied the foundation and basis of religion, the works of defenders and attackers, and the reasons for support and opposition. I can say that the result of these studies is to give religion a certain degree of credibility. Even if it is only for natural reasons, every belief that has not been distorted by sin or passion, and every natural noble spirit must love and accept it. I hope this confession, which I decided, voluntarily paid, personally written and signed, can be displayed to others in the future. I will not be ashamed of the gospel, but will wish it a beautiful fruit! (Excerpted from Alessandro Volta, Epistolario, Vol.5, p.29)

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