/kloc-One day in the early 7th century, Cobis Herr, the owner of an optical shop in Mitterberg, the Netherlands, lined up a convex lens and a concave lens to check the quality of the ground lenses. Looking through the lens, he found that the tower of the church in the distance seemed to be getting closer and closer, so he stumbled upon the principle of the telescope. 1608, he applied for a patent for his telescope, and made a binoculars according to the requirements of the authorities. It is said that there are dozens of opticians in Mitterberg who claim to have invented the telescope, but Libitch is generally regarded as the inventor of the telescope.
The news of the invention of the telescope soon spread in European countries. After learning the news, Italian scientist Galileo made one himself. The first telescope can only magnify the object three times. A month later, the second telescope he made can be magnified 8 times, and the third telescope can be magnified 20 times. 1609 10 in June, he made a telescope with a magnification of 30 times.
Galileo observed the night sky with a self-made telescope and found for the first time that the surface of the moon was uneven, covered with mountains and craters. Since then, four moons of Jupiter and the sunspot movement of the sun have been discovered, and the conclusion that the sun is rotating has been drawn.
Almost at the same time, the German astronomer Kepler began to study telescopes. He proposed another astronomical telescope in bending optics, which consists of two convex lenses. Unlike Galileo's telescope, it has a wider field of vision than galileo telescope. But Kepler didn't make the telescope he introduced. Sagana first made this telescope between1613-1617. He also made a telescope with a third convex lens according to Kepler's suggestion, and turned the inverted image of the telescope composed of two convex lenses into a positive image. Sagana made eight telescopes, one for observing the sun, and no matter which one can see sunspots with the same shape. Therefore, he dispelled many people's illusion that sunspots may be caused by dust on the lens, and proved that sunspots are really observed. When observing the sun, Sagina installed special shading glass, but Galileo did not add this protective device. As a result, he hurt his eyes and finally became almost blind.
In order to improve the accuracy of the telescope, Huygens of the Netherlands built a telescope with a tube length of nearly 6 meters in 1665 to explore Saturn's rings, and later made a telescope with a tube length of nearly 4 1 meter.
A telescope with an objective lens and an eyepiece is called a refractive telescope. Even if the lens barrel is lengthened and the lens is machined accurately, the chromatic aberration cannot be eliminated. 1668 The reflective telescope of British scientists solved the problem of chromatic aberration. The first anti-telescope is very small, and the aperture of the mirror in the telescope is only 2.5 cm, but we can clearly see the profit and loss of Jupiter's satellite and Venus. 1672, Newton made a larger reflecting telescope and gave it to the Royal Society, which is still kept in the library of the Royal Society.
Newton once thought that color difference was hopeless, but later, it turned out that he was too pessimistic. 1733, an Englishman Hal made an achromatic refracting telescope. 1758, the same telescope was made in Boland, London. He used glasses with different refraction principles to make convex lenses and concave lenses respectively to offset the colored edges they formed.
However, it is not easy to make a big shot. At present, the largest refracting telescope in the world has a diameter of 102 cm and is installed at the Addis Observatory.
Reflective telescopes have developed rapidly in astronomical observation. 1793, a reflective telescope was built in Hessel, England. The reflector is130m in diameter, made of copper-tin alloy and weighs1t. 1845 reflecting telescope made in Ross, England. The diameter of the reflector is1.82m.. Mount Wilson Observatory 19 13 anti-telescope, with a diameter of 254m. 1950, a reflective telescope with a diameter of 5.08 meters was installed on Paloma Mountain. 1969, a reflector with a diameter of 6 meters was installed on Pastuhov Mountain in the North Caucasus of the Soviet Union. It was the largest reflective telescope in the world at that time, and now most large observatories use reflective telescopes.
History of generators
/kloc-at the beginning of the 0/9th century, an important subject that scientists studied was the method of obtaining electricity cheaply and conveniently.
1820, after Oster successfully completed the experiment that electrified wires could deflect the magnetic needle, many scientists conducted further research at that time: the deflection of the magnetic needle was influenced by the force, which came from the charged flowing electric power. So, can mechanical force be transformed into electrical energy through magnetism? The famous scientist Ampere is one of these researchers. He tried many methods, but he made a fundamental mistake and the experiment was unsuccessful.
Clayton, another scientist, did an experiment at 1825: he inserted a magnet into a cylindrical coil, which he thought might get current. In order to prevent the magnet from affecting the current detected by the ammeter, he connected the ammeter to the next room with a long wire. Without an assistant, he had to insert the magnet into the coil and then ran to the next room to see if the ammeter pointer was deflected. Now it seems that his device is completely correct and the experimental method is correct. However, he made a really regrettable mistake, that is, the deflection of the ammeter pointer only happened at the moment when the magnet was inserted into the coil. Once the magnet is inserted into the coil and does not move, the ammeter pointer returns to its original position. So when he inserted the magnet, he quickly ran to the next room to look at the ammeter. No matter how fast it is, he can't see the deflection of the ammeter pointer. If he had an assistant, if he put the electric meters in the same room, he would be the first person to convert mechanical energy into electrical energy. However, he missed this good opportunity.
Six years later, on August 29th, 183 1, American scientist Faraday successfully converted mechanical force into electricity. His experimental device is no different from Clayton's, except that he puts the ammeter beside it. When the magnet is inserted into the coil, the pointer obviously deviates. He succeeded. The mechanical force of moving the magnet by hand is finally converted into electricity to move the charge.
Faraday took the hardest step. He went on studying. Two months later, he trial-produced the first real generator that can generate stable current. It marks that mankind has entered the electrical age from age of steam.
In the past 100 years, there have been many modern forms of power generation, including wind power generation, hydropower generation, thermal power generation, tidal power generation and so on. The structure of the generator is getting better and better, and the efficiency is getting higher and higher, but the basic principle is the same as Faraday's experiment: the moving closed conductor and magnet are indispensable.
The invention of nuclear magnetic vibrator
Nuclear magnetic resonance vibrometer is widely used in the research of organic matter, chemical reaction kinetics, polymer chemistry, medicine, pharmacy and biology. In the past 20 years, due to the rapid development of this technology, it has become one of the most important analytical technologies in the field of chemistry.
As early as 1924, Austrian physicist Pauli suggested that some nuclei might have spin and magnetic moment. The word "spin" comes from the classical images of charged particles, such as protons and electrons rotating around their own axes. This kind of motion will inevitably produce angular momentum and magnetic dipole moment, because the rotating charge is equivalent to a current coil, and from the classical electromagnetic theory, they will produce a magnetic field. Of course, this explanation is only a more vivid comparison, and the actual situation is much more complicated than this.
The situation of nuclear spin can be expressed by the spin quantum number I, and the spin quantum is obtained. The atomic number of the mass number has the following relationship:
Mass number atomic number spin quantum number (I)
Odd odd or even 1/2, 3/2, 5/2 ...
Even 0
Even and odd 1, 2, 3 ...
1 & gt； The nucleus of 0 will produce a magnetic field when spinning; The charge distribution of the nucleus with I 1/2 is spherical; However, the nucleus with I≥ 1 has a magnetic pole moment because its charge distribution is not spherical.
The nucleus of I 0 is placed in a strong magnetic field, and the energy level will split under the action of the strong magnetic field. If electromagnetic radiation with a frequency suitable for its energy level is used, the absorption of * * * vibration will occur, hence the name of * * * vibration in nuclear magnetic resonance.
Stern and Guelleh observed the magnetic deflection of lithium and silver atoms in the atomic beam experiment of 1924, and measured the atomic magnetic moment caused by unpaired electrons.
1933, Stern et al. measured the magnetic moment of protons. 1939, Bila made the first nuclear magnetic resonance experiment. 1946, Puxil and Bushehr of the United States simultaneously presented the experimental report of proton nuclear magnetic resonance. At first, they used nuclear magnetic resonance (NMR) to study the energy exchange among solid substances, nuclei and the nature of the surrounding environment. Because of this, the two of them won the 1952 Nobel Prize in Physics. In 1950s, the method of nuclear magnetic resonance was applied to the field of chemistry. 1950, proctor and Yu, two physicists from Stanford University in the United States, used aqueous NH 4NO3 as the source of nitrogen nuclei. When measuring the magnetic moment of 14N, they found two * * vibration signals with completely different properties, and thus found that the * * vibration condition of the same nucleus can absorb energy with different chemical environments, that is, nuclear magnetic resonance. This phenomenon is called "chemical shift". This is due to the interaction between the magnetic field formed by the electrons outside the nucleus and the external magnetic field. Chemical shift is an important basis for identifying functional groups. Because the size of chemical shift is closely related to the properties of bonds and the types of bonding elements. In addition, the magnetic interaction between each group of nuclei constitutes spin-spin coupling. This effect often makes each group of nuclei with different chemical shifts present not a single peak but multiple peaks on the vibration absorption diagram. This situation is determined by the number of adjacent nuclei in the molecule, and the distance is determined by factors such as symmetry, so it is helpful to prompt the whole molecule.
Due to the above achievements, a high resolution NMR oscillator has been developed. The nucleus that began to be measured is mainly hydrogen nucleus, which is due to its strong nuclear magnetic resonance signal. With the improvement of the instrument performance, the cores of 13C, 3 1P and 15N can also be measured, and the magnetic field used by the instrument becomes stronger and stronger. IT (Trass) magnetic field was made in 1950s, 2T magnetic field was made in 1960s, and 5T magnetizer was made by using magnetization phenomenon. In 1970s, 8T magnetic field was created. Now, the nuclear magnetic resonance vibrometer has been applied to various chemical systems ranging from small molecules to protein and nucleic acids.
Invention of emission spectrometer
Newton, a famous British scientist, observed the spectrum with a prism in 1666, which can be said to be the earliest spectral experiment. Since then, many scientists have been engaged in the study of spectroscopy. 1800, the British astronomer Herschel measured the thermal effects of various parts of the solar spectrum and discovered infrared rays for the first time in the world. 180 1 year, Ritter discovered ultraviolet rays. 1802, wollaston observed the discontinuity of the solar spectrum and found many black lines in the middle, which was an important discovery, but he mistook it for the dividing line of colors. 1803, Thomas Jin Yang, a British physicist, conducted an interference experiment of light and provided a method for measuring wavelength for the first time.
German physicist Flawn Hof rediscovered and drew the solar spectrum map, which contains more than 700 black lines, and marked the important black lines with letters A to H (called "Flawn Hof Line"). These black lines later became the standard for comparing the dispersion rates of different glass materials. These results were published in 18 14 to 18 15. Fraunhofer also invented the diffraction grating. At first, he wound silver wire around two screws to make a grating. Later, he built a engraving machine and made a transmission grating by marking the glass with diamonds.
The application research of spectral analysis began in Kirchhoff and Bunsen. Ben is a chemistry professor in Hamburg, Germany. He invented the bunsen burner and studied the changes of various substances in high-temperature flames. Kirchhoff is a physics professor in Hamburg who is familiar with optics. The two of them cooperated to form the first shuttle mirror spectrometer (spectroscope). The instrument uses the technology pioneered by Newton 1666 to make the light pass through the prism and spread into a rainbow band (spectrum). They use a lens to integrate the light emitted when the substance burns in bunsen burner into a beam of parallel light, pass through a narrow slit, pass through a prism, and use a telescope to enlarge and observe the spectrum.
Kirchhoff and Bunsen found that each chemical element has a unique color when it burns, which can be identified accordingly. 1860 and 186 1 year, they discovered cesium and rubidium by spectrometer. Later, with the help of spectral analysis, we found that many elements on the earth are also found in the sun. 1868, French astronomer Zhan Sen and British astronomer Royer discovered an element that had not been discovered on the earth at that time through spectroscopy. They thought it was a unique element in the sun's atmosphere and named it helium, which means "the sun". This spectral method is also applied to astronomy.
With the rapid development of spectral method research, new problems have emerged. One of the main problems is the lack of wavelength standard with sufficient accuracy, which makes the observation results confusing and unable to communicate.
1868, Estren published a "standard solar spectrum" chart, which recorded the small wavelengths of thousands of Fraunhofer lines, with the unit of10-8cm, accurate to 6 digits, and provided extremely useful information for spectrologists. In memory of him, 10-8cm was later written as "A" in estrin. Ten years later, it was replaced by a more accurate Roland data table.
Modern spectrometers use diffraction gratings instead of prisms. This is a wooden board engraved with thousands of lines, which separates the light, then photographs or records the spectrum, and then analyzes it with electronic instruments.
Spectrometer is widely used in metallurgy, geology, environment and other fields
History of lightning rod
First, lightning rod is a lightning protection device made and used by working people in our country. It is said that Czech priest Procop Devis installed the first lightning rod in 1754. More people think that Franklin of America made the world's first lightning rod in 1753. In fact, lightning rods were manufactured and used for the first time in China before 1688.
As early as the Three Kingdoms period (AD 220-280) and the Southern and Northern Dynasties period (AD 420-58 1 year), there were records of "lightning protection rooms" in ancient books in China. According to Wang Rui's Su in the Tang Dynasty, it was suggested in the Han Dynasty (from 206 BC to 220 AD) that the tiles could be made into fishtails and placed on the roof to prevent the fire caused by lightning. Lightning protection devices have also been found in some ancient buildings in China. After visiting China, Cabriobe Damaganlan, a French traveler, wrote "New Things in China" on 1688. It was recorded in the book: "At that time, there was a cock cocked at both ends of the roof of a new house in China, and its dragon mouth spit out a tortuous metal tongue, which stretched into the sky, and the root of the tongue was connected with a thin wire and went straight to the ground. This wonderful device will show its magical power in the moment of lightning. If lightning strikes the house, the current will flow down from Longkou to the ground without causing any damage. " It can be seen that the first lightning rod in the world was made by intelligent working people in China.
Second, lightning rods have developed to today, and safer lightning rods have been found in the world. The safer lightning rod is not a needle, but a feather duster. This lightning rod was invented by two Americans. According to a recent report in The New York Times, USA, the center of this lightning rod is a tube, and 2000 thin wires are led out from its top and distributed radially. This way can better disperse the static charge accumulated around the building.
Third, "the lightning rod is out of date." At present, China has successfully developed a semiconductor lightning arrester, and its lightning protection effect far exceeds that of lightning rods and similar products produced in the United States, France and Australia. The semiconductor lightning eliminator has two functions: (1) When there is a strong thunderstorm over the building, it emits a corona spark as long as 1 m to neutralize the sky current and reduce the lightning strike; (2) When lightning strikes, the related devices on the semiconductor lightning eliminator can block the powerful current released by lightning strikes.
Xie Guangrun, a famous lightning protection expert in China and a professor at Wuhan Institute of Water Conservancy, suggested installing this semiconductor lightning arrester on high-rise buildings to protect national property. Xie Guangrun said that at present, 24 units in China's strong minefield have installed semiconductor lightning eliminators. After several years of testing, it is proved that it has indeed turned the building from danger to safety again and again. He called on relevant units, especially the departments of national defense engineering, meteorology, electric power, communication and broadcasting, to promote semiconductor lightning eliminators as soon as possible to reduce lightning losses.