Hello everyone. How do you watch this intellectual 'Minani' program well, actually this Science Cookie channel video with? I think most of you may watch it on smartphone. Oh you watch it on computer.
The first Wireless communication device that can said as the beginning of smartphone that we are so familiar with was developed by DR. Martin Cooper's research team who worked at Motorola in 1973, and this is 'Dyna TAC 8000X' which was the first cellular phone in the world. This phone weight about 850 grams. Which means it is almost 1kg. After 35 years later, in a way a very short time, in January of 2007, starting with the iPhone, which was created by Steve Jobs' innovative ideas, thanks to intensive development of many scientific technologies. smartphone was able to become popular like today. We already know that this development of wireless communication does not only enrich the quality of our life living in modern society but also is the indispensable elements of the Fourth Industrial Revolution to come in the future. But have you ever wondered even once? How can this small device called 'smart phone' receive phone call, text, and video information without restrictions? How can the so called Wi-fi or blue tooth be able to become the bridge to connect electronic devices that are so far away? Furthermore, how can devices like transportation card or hi-pass send their information to long distance, or how can they receive back from a long distance? Today, we are going to check with science cookie about story of 'radio wave', Radiowave, that is very thankful electromagnetic wave and led to the remarkable development of modern information communication, This electromagnetic wave called Radio wave refers to all electromagnetic waves using for communication including the microwave from the previous video. According to the radio regulation from the International Telecommunications Union, ITU, radio wave means all electromagnetic wave with the frequency between 3kHz to 3THz, if converted into wavelength, from 1mm to 100km. Starting from the highest frequency the order is, Extremely High Frequency (EHF),
Super High Frequency (SHF), Ultra High Frequency (UHF), Very High Frequency (VHF), High Frequency (HF),
Medium Frequency (MF), Low Frequency (LF), Very Low Frequency (VLF), Ultra Low Frequency (ULF),
Super Low Frequency (SLF), Extremely Low Frequency (ELF), and their representative use cases from right are radio astronomy, 5G wireless communication called '5G', wifi, bluetooth and smartphone, FM radio and DMB broadcast, living walki-talki and RFID, AM radio and radio-navigational facilities. Suarine Communications and communication inside the underground mine. Wait a minutes! But why do we use an electromagnetic wave as the communication method? As we talked about microwave before electromagnetic wave has the advantage of being able to be spread around the space freely because it does not need a medium. And also there's another merit. That is, it has the fastest speed in an observable universe which can transfer informations because electromagnetic wave moves at the speed of light. Imagine this! Don't you think it is incredible if you found a device that can transfer information at the speed of light in a space where no one exists? The first scientist to foretell the discovery of such tool was James Clerk Maxwell who represents the 19 century and was the genius scientists who established electromagnetism. Maxwell combined the characteristics of electronics and magnetics studied constantly from previous generation into 4 different kinds of formulas which were mathematically simple and beautiful, named electromagnetism. Especially among those formulas, based on the 3rd and the 4th, the Faraday's law and Ampere's law, he predicted the 'electromagnetic wave' the electromagnetic wave energy that spreads out the space. This prediction was proven through Hertz's tests and world become to put spur in earnest on the study of this amazing and surprisingly 'electromagnetic wave' . But even if the tool is so great, if you cannot make it, it is meaningless. To build 'electromagnetic wave' what should we do? The secret is if we can vibrate an electron existing in space very rapidly by some external factor, for example, to occur micro wave , 2.45 GHz, the range of micro wave , so if you can repeat this vibration every second, in other words, if you can vibrate the electrons 2450000000 times a second you can in theory, create the electromagnetic wage that corresponds to that field. Then how can you make electrons vibrate this fast? It is possible by using the principle of AC generator. if we talk about this in the video it may get too long so I will prepare this in the electromagnetic series later on. Back to the wave story by being able to make the range of wave that we want using that principle, human could send wanted information from a place to another using various waves. It still left some problems. Waves that spreads out like this had to be considered how to be sent to a specific target. Throughout the process, it was thought if there was a circuit that can only receive electromagnetic wave with specific vibration number, if we could make such circuit, could we not be able to make a circuit that can selectively receive the information loaded into that certain wave? This thought has created 'coil' which electricity can go in rotating which we are using and 'electric condenser', with two pole plates facing each other creating a magnetic field. These devices appears in a normal form inside the direct current, a current that flows in a regular size just like the batteries but in an alternation current, energy flowing through electric vibration it shows a very peculiar characteristics. Let's learn about coil first. When the current is flowing inside the coil, by the Ampere's law, you can see a magnetic field forming within the coil. if electricity does not flow regularly and go up and down with certain period because of the momentum of the magnetic field trying to maintain its intensity the jiggling of the current is disturbed. Such disturbing process is called induction reactance in physics. This induction reactance when the vibration gets faster and faster the magnetic field increases in size and disturbs more and more Next, let's look at the characteristics of the electric condenser. when the current flows through electric condenser, following the Gauss's law it stacks up at the each pole plate. if a current that jiggles is supplied, just like in the coil example, the jiggling of the current is disturbed by the electric energy made by the stacked charge. This phenomenon in physics is called capacity reactance this type of reactance when the vibration is slower more charge gets stacked up in each polar plate and get disturbed even greater. When the coil and the condenser exist at the same time in a AC circuit, a peculiar characteristic can be found within the circuit. which is! due to capacity reactance and induction reactance, the moment the electromagnet vibration supplied to the circuit has a special vibration number, both reactances' disturbance becomes very small which is shocking. This type of vibration is called an oscillation frequency or resonant frequency and the circuit having such characteristics, made by the coil and the condenser, is called the resonance circuit or the RLC circuit meaning that can resonate only with a certain wave length and receive the information of it. Using such resonance circuit, the tool to selectively receive the information inside a certain wave length is the antenna. Using this antenna, catching a specific wave out of the several waves being transmitted is the most basic principle used in most of the communication method of today. Thanks to the discovery of radio wave that made all this possible, the humans constantly researched about how to generate and receive such radio wave. And the fact that within a short time of only about 100 years we were able to create information communication civilization of the modern information society, is very amazing. But the wonder that the discovery of electromagnetic wave brought does not end here. By finding this specific electromagnetic wave, the prospect of the quantum mechanics was extended, and we also discover the DNA sequence listing that triggered the study of life's genetic phenomenon. Aren't you wondering about an electromagnetic wave X -ray that led to an amazing discovery? I've prepared something for those who are wondering about it If you click here, you can hear a very interesting story about the x-ray.
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Have you watched one of my videos regarding the super-string theory? I said in the super-string theory video that there are 4 kinds of powers in the world Human beings only succeeded in mastering one of 4 powers Can you guess what it is?