15.04.2017 18:46
1875
What is a magnet and why is it needed?
At your home, on the refrigerator door, you probably have beautiful pictures called magnets. Why are they called that? That's right, because they are held on the refrigerator by a magnet that is attached to the back side.
But the magnet is used not only to attach pictures to the refrigerator. Interested to know what else? We'll tell you about it. But first, let's talk about what a magnet actually is.
Its most famous property is the ability to attract metal objects to itself - paper clips, nails, needles, and basically anything, the main thing is that it is made of metal. This happens with the help of a force called magnetism.
Each magnet has two ends called north and south poles. The north pole of one magnet attracts South Pole the other and then both of them are magnetized. By the way, our planet Earth is also a giant magnet, which has two poles, which are located at the top and bottom of the planet.
There are three main types of magnets - permanent; temporary; and electromagnets. You probably want to ask where they come from?
Permanent magnets are made from natural materials such as iron, ceramics, cobalt, etc.
Temporary magnets are those that have their magnetic (attracting) properties only in the vicinity of permanent magnets. Thus, any metal objects can be considered temporary magnets - scissors, paper clips, pins, etc.
An electromagnet is a coil on which a metal wire is tightly wound. Such a magnet works only if an electric current passes through a wire wound on a coil and gives it magnetic, attractive properties.
The attractive force of an electromagnet depends on the change in the magnitude and direction of the wire passing through it. electric current.That is, the more powerful the current, the stronger magnet attracts. However, an electromagnet can only work if electricity is connected. Once the electricity is turned off, it loses its power.
Magnets are a very useful thing. For example, they are needed to ensure that the doors of our refrigerators close tightly. Or to collect needles scattered on the floor without getting pierced.
And huge magnets are used in various factories. They are fixed to a crane and thanks to this, heavy metal parts are moved.
The compass needle is also a tiny magnet, so it always points in the direction North Pole. With the help of a compass, people find their way to any part of the Earth. They are used not only on the ground, but also on airplanes and ships.
To understand how they work magnetic poles, you can conduct a simple experiment: take two magnets in your hands and try to press them one against the other.
Different poles (north and south) attract each other. And the same ones (north and north or south and south) repel each other. You will feel this when you begin to bring the magnets closer to each other.
Also, at home you can conduct another interesting experiment called “Floating Compass”. To do this, take (or rather ask your mother) an ordinary sewing needle and magnetize it.
How to do it? To give a needle the properties of a magnet, you need to run a magnet over it approximately 50 times in the same direction. After this, stick a needle into a piece of cork. Place the cork in a bowl of water.
That's all. When the needle calms down, you will see that it is always directed only in one direction - to the north.
What is a magnet? Types of magnets. A magnetic field. A magnet is a body that can attract iron. Or: a magnet is an object made of a certain material that creates a magnetic field.
Magnet - what is it?
Magnets are made up of millions of molecules arranged in groups called domains. Each domain behaves like a mineral magnet, having a north and south pole. When the domains have the same orientation, their strength combines to form a larger magnet. Iron has many domains that can be oriented in one direction, i.e. magnetize. Domains in plastic, rubber, wood and other materials are in a disordered state, their magnetic fields are multidirectional and therefore these materials cannot be magnetized.
Each magnet has at least one "north" (N) and one "south" (S) pole. Scientists have agreed that the lines magnetic field come out of the "north" end of the magnet and enter the "south" end of the magnet.
If you take a piece of magnet and break it into two pieces, each piece will again have a "north" and a "south" pole. If you again break the resulting piece into two parts, each part will again have a “north” and a “south” pole. It doesn't matter how small the resulting pieces of magnets are, each piece will always have a "north" and a "south" pole. It is impossible to get it to form magnetic monopole(“mono” means one, monopole means one pole), that is, a piece with one pole.
Types of magnets
There are three main types of magnets:
- permanent (natural) magnets;
- temporary magnets;
- electromagnets.
Natural magnets, called magnetic ore, are formed when ore containing iron or iron oxides is cooled and magnetized by earth magnetism. Permanent magnets have a magnetic field in the absence of electric current because their domains are constantly oriented in the same direction.
Temporary magnets are magnets that act as permanent magnets only when they are in a strong magnetic field and lose their magnetism when the magnetic field disappears. Examples include paper clips and nails, as well as other “soft” iron products.
Electromagnets have a metal core with induction coil through which electric current passes.
What is a magnetic field?
A magnetic field is the area around a magnet within which the influence of the magnet on external objects is felt.
Human senses cannot see the magnetic field, but assistive devices prove that the magnetic field exists.
Sprinkle iron filings onto the paper and place a magnetic bar in the middle of the paper. The chips will move, forming arcs around the poles of the magnet. The pattern that the chips forms is a pattern of lines of the magnetic field of the magnetic bar.
Our Earth is surrounded by a magnetic field. This has always been the case, at least since the origin of the Earth. And everything that is on Earth, including people, animals and plants, is exposed to invisible power lines this field. But, at the same time, the human body has its own magnetic field, which arises as a result of the flow of blood through the vessels. IN different organs it may vary. In a healthy body and normal conditions there is complete correspondence and interaction of external and internal magnetic fields.
Magnetism is as necessary for all living things as water, air, food or sunlight. Its impact on terrestrial magnetism renders the Sun.
Even in ancient times, people discovered unique properties certain stones - attracting metal. Nowadays, we often come across objects that have these qualities. What is a magnet? What is his strength? We will talk about this in this article.
An example of a temporary magnet is paper clips, buttons, nails, a knife and other household items made of iron. Their strength lies in the fact that they are attracted to a permanent magnet, and when the magnetic field disappears, they lose their properties.
The field of an electromagnet can be controlled using electric current. How does this happen? A wire wound in turns on an iron core changes the strength of the magnetic field and its polarity when a current is supplied and changed.
Types of permanent magnets
Ferrite magnets are the most famous and actively used in everyday life. This black material can be used as fasteners various items eg for posters, for wall boards used in office or school. They do not lose their attractive properties at temperatures not lower than 250 o C.
Alnico is a magnet consisting of an alloy of aluminum, nickel and cobalt. This gave it its name. It is very resistant to high temperatures and can be used at 550 o C. The material is lightweight, but completely loses its properties when exposed to a stronger magnetic field. Mainly used in the scientific industry.
Samarium magnetic alloys are high performance materials. The reliability of its properties allows the material to be used in military developments. It is resistant to aggressive environment, high temperature, oxidation and corrosion.
What's happened Neodymium magnet? It is the most popular alloy of iron, boron and neodymium. It is also called a supermagnet, as it has a powerful magnetic field with high coercive force. By observing certain conditions during operation, a neodymium magnet can retain its properties for 100 years.
Use of neodymium magnets
It is worth taking a closer look at what a neodymium magnet is? This is a material that is capable of recording the consumption of water, electricity and gas in meters, and not only. This type of magnet belongs to permanent and rare earth materials. It is resistant to fields of other alloys and is not subject to demagnetization.
Neodymium products are used in the medical and industrial industries. Also in domestic conditions they are used for attaching curtains, decorative elements, and souvenirs. They are used in search instruments and electronics.
To extend their service life, magnets of this type are coated with zinc or nickel. In the first case, spraying is more reliable, as it is resistant to aggressive agents and can withstand temperatures above 100 o C. The strength of the magnet depends on its shape, size and the amount of neodymium included in the alloy.
Applications of Ferrite Magnets
Ferrites are considered the most popular magnets among permanent species. Thanks to strontium included in the composition, the material does not corrode. So what is it - ferrite magnet? Where is it used? This alloy is quite fragile. That's why it is also called ceramic. Ferrite magnets are used in automotive and industrial applications. Used in various techniques and electrical appliances, as well as household installations, generators, and acoustic systems. In automobile manufacturing, magnets are used in cooling systems, window lifters, and fans.
The purpose of ferrite is to protect equipment from external interference and prevent damage to the signal received via the cable. Thanks to this, they are used in the production of navigators, monitors, printers and other equipment where it is important to obtain a clean signal or image.
Magnetotherapy
A procedure called magnetic therapy is often used and is carried out in medicinal purposes. The action of this method is to influence the patient's body using magnetic fields under low-frequency alternating or DC. This treatment method helps get rid of many diseases, relieve pain, strengthen immune system, improve blood flow.
It is believed that diseases are caused by disturbances in the human magnetic field. Thanks to physiotherapy, the body returns to normal and general state is improving.
From this article you learned what a magnet is, and also studied its properties and applications.
TASS DOSSIER. On February 16, 2018, at the Russian Investment Forum in Sochi, the founder, CEO and main owner of the Russian retail chain Magnit, Sergei Galitsky, entered into an agreement with VTB to sell the bank a controlling stake in the retailer - 29.1% of shares - for 138 billion rubles.
It is expected that in the near future the post of general director of Magnit will be taken by the chairman of the board of directors Khachatur Pombukhchan.
"Magnet" is one of largest companies retail trade in Russia and Europe. As of the beginning of 2018, there were 16 thousand 350 stores under the management and brand of Magnit, including 243 hypermarkets. In total, the company operates in 2 thousand 665 cities of Russia. Most stores are opened in the Southern, North Caucasian, Volga and Central federal districts. The company has one of the largest transport and logistics networks in Russia. "Magnit" ranks 1st among Russian retailers in terms of revenue (according to the company "InfoLine-Analytics") and 7th place in Russia among all Russian companies (according to the RBC-500 rating). Registered in Krasnodar.
Story
The founder of the company is entrepreneur Sergei Galitsky. In July 1995, together with his partner Alexei Bogachev, he created the Thunder company (now Joint-Stock Company, JSC "Tander") and became her general director. Initially the company was engaged wholesale supplies perfumes in southern regions Russia. In 1998, the company opened the first retail supermarket "Magnit" in Krasnodar. Subsequently, stores were created in other cities, mainly in the south of Russia. Galitsky avoided competition with large retail chains, developing business in small towns and positioning his outlets as convenience stores with low prices. In the early 2000s they were merged into trading network called "Magnet".
In 2003, Galitsky registered Magnit OJSC (now PJSC), which received 100% of Tander shares.
In 2006, Magnit listed its shares on the stock exchange, and with the proceeds the construction of the chain's hypermarkets began. Since 2010, the company has been developing a network of Magnit-Cosmetics retail stores. In its stores "Magnit" sells a range of products own brands: “Family Secrets”, “Master Shine”, “North Harbor”, “Saving Smart”, “ Trading house Smetanin" and others.
Indicators
Based on the results of the last reporting year 2016, Magnit’s consolidated revenue for international standards financial statements amounted to 1 trillion 74 billion rubles. (an increase of 4.6% compared to 2015), net profit amounted to 1.14 billion rubles. (Before this, Magnit showed a net loss for the last three years).
According to Spark-Interfax, Magnit accounts for 25% of the revenue of all retail trade in the Russian Federation and 22% of the revenue of all companies registered in the Krasnodar Territory.
Management
Since 2006, Sergei Galitsky has been the general director of Magnit, and since 2010, also the chairman of the board. Chairman of the Board of Directors - Khachatur Pombukhchan.
Owners
At the end of the third quarter of 2017, Galitsky owned 35.11% of the company’s shares. The largest minority shareholder is the American investment company OppenheimerFunds Inc. More than 50% of the retailer's shares are traded on the open market. Current market capitalization is about $10 billion.