Soon, Faraday's apprenticeship ended and he became a formal bookbinder in another bookstore. The new owner admired him very much and promised Faraday to be the heir of the bookstore in the future. However, Faraday's ambition is not here. He got up the courage and wrote a letter to David, hoping that David could help him find a position where he could get in touch with technology.
David warmly received Faraday and advised him to reconsider his ideal. He said humorously, "Science is like an eccentric woman. Although you are full of enthusiasm for her, the return you get is extremely small! " "
Faith can move mountains. 18 13 years, Faraday's wish finally came true. He entered the royal college laboratory and worked as an assistant experimenter for David. A few months later, he got a very rare opportunity to study-to go to Europe for an academic investigation with David. The trip left an unforgettable impression on Faraday. In his diary, he recorded in detail the contents of David's lectures and experiments in various places, as well as the experimental methods and styles of scientists from various countries. The natural scenery and customs he saw along the way also aroused his great interest. Faraday is optimistic and compassionate by nature, and has a deep love for nature and working people living at the bottom. This trip strengthened his belief in devoting himself to science and benefiting mankind.
As soon as Faraday returned to London, he began to work in the laboratory. In two or three years, after practice, Faraday has excellent experimental ability. Under the guidance of David, he embarked on the road of independent research.
18 16, Faraday made his debut at the age of 25, and published his first chemical paper in Science Quarterly. 18 18, Faraday wrote an academic report on flame, boldly pointing out the fallacy of the famous theory. Under the guidance of David, he studied and worked hard and eventually became a promising young chemist.
168 1 In the summer of, a merchant ship sailing in the Atlantic Ocean was struck by lightning. As a result, all three compasses on the ship failed: two demagnetized and the other pointer fell backwards. Another time, a hardware store in Italy was struck by lightning, and later it was found that some steel knives were magnetized. No one could explain these phenomena because the nature of lightning was not clear at that time. 100 years, the mystery of electromagnetism has become the goal of many scientists.
1820, Oster announced his discovery that when the electrified wire is placed above the magnetic needle, the magnetic needle will deflect. This discovery immediately caused a sensation in the whole physics field. There is such a wonderful relationship between the two phenomena that people think they are irrelevant. This discovery has become a major breakthrough in modern electromagnetism, and scientists all over the world have turned to electromagnetic research.
Faraday fully understands that this discovery is of immeasurable significance. He is determined to explore further along the gap opened by Oster. Encouraged by David, young chemists resolutely broke into the unknown physical field of electromagnetism.
Faraday decided to explore the mystery from practice. He made a detailed comparison and research on the collected data about electromagnetic phenomena, and re-examined them one by one with experiments. This experiment is quick and interesting. 182 1 In the summer of, he published a paper on the research progress of electromagnetism in the Annual Report of Philosophy. In this paper, Faraday called the force of current on the magnetic needle "rotating force". Although he didn't touch the essence in theory, he skillfully used this "rotating force" in his experiments to make a magnet rotate around the current or a current-carrying conductor rotate around the magnet.
Soon, Ampere published a research report. Faraday coincides with ampere.
Faraday's first success gave him great encouragement. He is more confident and determined to be the pioneer of electromagnetism, a brand-new science. According to a lot of experiments, he is convinced that electricity and magnetism are two sides of the same thing, just like the patterns and characters of copper coins. Since current can produce magnetism, why can't magnetism produce current? In the autumn of 182 1, Faraday wrote a flashing idea in his diary, "electricity is produced by magnetism!"
This is a difficult climb. In order to achieve this goal, Faraday experienced numerous failures and carried out experimental research for 10 years.
This is a boring experiment:
A coil is wrapped around a wooden stick several meters long with copper wire, and the copper wire is wrapped with cloth tape for insulation. Then, outside the first layer of coil, the second layer, the third layer and the twelfth layer are also wound, and each layer is insulated.
The first, third and fifth odd-numbered layers are connected in series, and then the second, fourth and sixth even-numbered layers are connected in series, thus making two combined coils which are closely combined and insulated from each other. Finally, one set of coils is connected to the switch and battery, and the other set of coils is connected to the ammeter. Turn on the power and keep the pointer still; Increase the battery, increase the current, and the pointer still does not move!
Faraday did not despair, but insisted on exploring on the rugged road. In a blink of an eye, 10 years passed.
183 1 This year is the most unforgettable year in Faraday's life. It seems particularly sunny this autumn. The weather has some coolness, Faraday is still wearing that simple coat and working nervously in the laboratory. His electrical experiment entered the most critical stage.
At this time, Faraday has increased the battery pack to 120 batteries. This means that the current of the primary coil is increased by 120 times. I wonder how many coils he has changed for his experiment.
Faraday was absorbed in the operation. He carefully closed the switch, more current passed through the coil, and soon the wire became hot. Faraday turned his head and stared at the galvanometer. The pointer seems to be fixed, but it does not move.
Why is this?
He consulted all the experimental records, reflected on the design ideas and experimental methods, and checked the experimental instruments one by one, not even letting go of a wire. When checking the galvanometer, Faraday inadvertently noticed that he turned on the power first and then turned to observe the galvanometer in every experiment.
Could this be the problem?
He immediately rearranged the experimental platform for inspection. This time Faraday specially put the galvanometer next to the power switch, so that his eyes can always monitor the pointer during the operation.
Faraday stared intently at the galvanometer, and then turned on the power switch by hand. Hardly had the wire been connected when the ammeter pointer jumped! This time is too short, you can't find it without paying attention. Faraday ignored this detail in many experiments in the past, and finally caught this fleeting "moment" this time.
Faraday promoted and improved the experimental instrument.
He replaced the core of the coil with a soft iron ring, and the effect was more obvious. At the moment when the primary coil current is disconnected or connected, the ammeter pointer connected to the secondary coil swings badly.
Faraday began to think. On the surface, this experiment induces a secondary current from a primary current, in other words, it changes from electricity to electricity, which seems to have nothing to do with magnetism. On the other hand, if this discovery only means "transforming from electricity to electricity", there is still a difficult question to explain-why does the secondary coil generate current at the moment when the primary current is turned on or off? Could this sudden change in primary current be related to magnetism?
In order to find out this difficult problem, Faraday continued his experiment. A few days later, he further discovered that if the position between the primary coil and the secondary coil is changed, or the current intensity of the primary coil is changed, the secondary coil also has induced current. Faraday suddenly understood that the magnetic effect produced by the current in the primary coil must have induced the current in the secondary coil. In order to confirm this judgment, Faraday simply removed the primary coil and replaced it with a magnet. He let the magnet pass through the secondary coil ring, and the pointer of the galvanometer oscillated with the movement of the magnet. The mystery was finally solved: it was the magnetic force of motion that produced the current. This is the famous electromagnetic induction phenomenon, which reveals the dialectical relationship between electricity and magnetism and lays the foundation for modern electromagnetism.
Besides, after Faraday discovered the phenomenon of "moving magnetic power generation", he quickly summed up its law: when a part of the conductor of a closed circuit moves to cut the magnetic field lines, a current will be generated in the conductor. This law inspired Faraday to develop a generator: let the conductor cut the magnetic field lines regularly, thus generating continuous current. After several days' deliberation, Faraday drew a sketch of the generator in his diary of 183 10/October 28th (as shown in the figure): a disk fixed on the rotating shaft was placed between two magnetic poles and kept rotating. Obviously, a disk can be regarded as several copper bars with the length equal to the radius. When rotating the disk, each copper bar must cut the magnetic field lines. When the two ends of the external circuit are respectively connected to the rotating shaft of the generator and the edge of the disk, the external circuit and the disk form a closed loop to generate current.
Faraday's idea was confirmed by experiments-the disk generator was built soon. One day Faraday performed his generator at the Royal Society, and a lady said coldly, "What's the use of this thing?" Faraday tactfully replied, "madam, you shouldn't ask a newborn baby what to do." No one can predict what will happen when the baby grows up? "
electrophoresis
Electrophoresis means that under certain conditions, the distance (mobility) of charged particles in unit time is constant under the action of unit electric field intensity, which is the physical and chemical characteristic constant of charged particles. Different charged particles electrophorese in the same electric field because of different charges or different charge-mass ratios, and after a certain period of time, they separate from each other because of different moving distances. The separation distance is proportional to the applied electric field voltage and electrophoresis time. Under the action of external DC power supply, colloidal particles move directionally to cathode or anode in dispersion medium. Separation of substances by electrophoresis is also called electrophoresis. The colloid has electrophoresis phenomenon, which proves that the particles of colloid are charged. Various colloidal particles have different properties and absorb different ions, so they have different charges.