Why does a magnet attract or everything about magnetic fields
Why does a magnet attract or everything about magnetic fields
Magnets, like the toys stuck to your refrigerator at home or the horseshoes you were shown in school, have several unusual features. First of all, magnets are attracted to iron and steel objects, such as the door of a refrigerator. In addition, they have poles. Bring two magnets closer to each other. The south pole of one magnet will be attracted to the north pole of the other.
The north pole of one magnet repels the north pole of the other. The magnetic field is generated by electric current, that is, by moving electrons. Electrons moving around an atomic nucleus carry a negative charge. The directed movement of charges from one place to another is called electric current. An electric current creates a magnetic field around itself.
This field, with its lines of force, like a loop, covers the path of electric current, like an arch that stands over the road. For example, when a table lamp is turned on and a current flows through the copper wires, that is, the electrons in the wire jump from atom to atom and a weak magnetic field is created around the wire.
In high-voltage transmission lines, the current is much stronger than in a table lamp, so a very strong magnetic field is formed around the wires of such lines. Thus, electricity and magnetism are two sides of the same coin - electromagnetism.
The movement of electrons within each atom creates a tiny magnetic field around it. An electron moving in orbit forms a vortex-like magnetic field. But most of the magnetic field is created not by the movement of the electron in orbit around the nucleus, but by the movement of the atom around its axis, the so-called spin of the electron. Spin characterizes the rotation of an electron around an axis, like the movement of a planet around its axis.
In most materials, such as plastics, the magnetic fields of individual atoms are randomly oriented and cancel each other out. But in materials like iron, the atoms can be oriented so that their magnetic fields add up, so a piece of steel becomes magnetized. Atoms in materials are connected in groups called magnetic domains. The magnetic fields of one individual domain are oriented in one direction.
That is, each domain is a small magnet. Different domains are oriented in a wide variety of directions, that is, randomly, and cancel each other's magnetic fields. Therefore, a steel strip is not a magnet. But if you manage to orient the domains in one direction so that the forces of the magnetic fields combine, then beware! The steel strip will become a powerful magnet and will attract any iron object from a nail to a refrigerator.
Magnetic iron ore mineral is a natural magnet. But still, most magnets are made artificially. What force can force atoms to line up to form one large domain? Place the steel strip in a strong magnetic field. Gradually, one by one, all domains will turn in the direction of the applied magnetic field.
As the domains rotate, they will draw other atoms into this movement, increasing in size, literally swelling. Then the identically oriented domains will connect, and lo and behold, the steel strip has turned into a magnet. You can demonstrate this to your comrades using an ordinary steel nail. Place the nail in the magnetic field of a large neodymium magnet.
Hold it there for a few minutes until the nail domains line up in the desired direction. Once this happens, the nail will briefly become a magnet. With its help you can even pick up fallen pins from the floor.
Why doesn't a magnet attract everything?
In fact, the interaction of a magnet with substances has many more options than just “attracts” or “does not attract.” Iron, nickel, and some alloys are metals that, due to their specific structure, are very strongly attracted by a magnet.
The vast majority of other metals, as well as other substances, also interact with magnetic fields - they are attracted or repelled by magnets, but only thousands and millions of times weaker.
Therefore, in order to notice the attraction of such substances to a magnet, you need to use an extremely strong magnetic field, which you cannot get at home.
But since all substances are attracted to a magnet, the original question can be reformulated as follows: “Why then is iron so strongly attracted by a magnet that manifestations of this are easy to notice in everyday life?” The answer is: it is determined by the structure and bonding of iron atoms. Any substance is composed of atoms connected to each other by their outer electron shells.
It is the electrons of the outer shells that are sensitive to the magnetic field; they determine the magnetism of materials. In most substances, the electrons of neighboring atoms feel the magnetic field “at random” - some repel, others attract, and some generally try to turn the object around.
Therefore, if you take a large piece of a substance, then its average force of interaction with a magnet will be very small.
Iron and metals similar to it have a special feature - the connection between neighboring atoms is such that they sense the magnetic field in a coordinated manner. If a few atoms are tuned to be attracted to a magnet, they will cause all neighboring atoms to do the same. As a result, in a piece of iron all the atoms “want to attract” or “want to repel” at once, and because of this, a very large force of interaction with the magnet is obtained.
A magnet is a body that has its own magnetic field. In a magnetic field, there is some effect on external objects that are nearby, the most obvious being the ability of a magnet to attract metal.
The magnet and its properties were known to both the ancient Greeks and the Chinese. They noticed a strange phenomenon: small pieces of iron were attracted to some natural stones.
This phenomenon was first called divine and used in rituals, but with the development of natural science it became obvious that the properties were of a completely earthly nature, which was first explained by the physicist from Copenhagen Hans Christian Oersted.
He discovered in 1820 a certain connection between the electric discharge of current and a magnet, which gave rise to the doctrine of electric current and magnetic attraction.
Natural science research
Oersted, conducting experiments with a magnetic needle and a conductor, noticed the following feature: a discharge of energy directed towards the needle instantly acted on it, and it began to deviate.
The arrow always deviated, no matter from which side he approached.
A physicist from France, Dominique François Arago, began repeated experiments with a magnet, using as a basis a glass tube rewound with a metal thread, and he installed an iron rod in the middle of this object.
With the help of electricity, the iron inside began to be sharply magnetized, because of this various keys began to stick, but as soon as the discharge was turned off, the keys immediately fell to the floor.
Based on what was happening, a physicist from France, Andre Ampere, developed an accurate description of everything that happened in this experiment.
When a magnet attracts metal objects to itself, it seems like magic, but in reality the “magical” properties of magnets are associated only with the special organization of their electronic structure. Because an electron orbiting an atom creates a magnetic field, all atoms are small magnets; however, in most substances the disordered magnetic effects of atoms cancel each other out.
The situation is different in magnets, the atomic magnetic fields of which are arranged in ordered regions called domains. Each such region has a north and south pole. The direction and intensity of the magnetic field is characterized by the so-called lines of force (shown in green in the figure), which leave the north pole of the magnet and enter the south.
The denser the lines of force, the more concentrated the magnetism. The north pole of one magnet attracts the south pole of another, while two like poles repel each other. Magnets attract only certain metals, mainly iron, nickel and cobalt, called ferromagnets.
Although ferromagnetic materials are not natural magnets, their atoms rearrange themselves in the presence of a magnet in such a way that the ferromagnetic bodies develop magnetic poles.
Magnetic chain
Touching the end of a magnet to metal paper clips creates a north and south pole for each paper clip. These poles are oriented in the same direction as the magnet. Each paper clip became a magnet.
Countless little magnets
Some metals have a crystalline structure made up of atoms grouped into magnetic domains. The magnetic poles of the domains usually have different directions (red arrows) and do not have a net magnetic effect.
Formation of a permanent magnet
Typically, iron's magnetic domains are randomly oriented (pink arrows), and the metal's natural magnetism does not appear. If you bring a magnet (pink bar) closer to the iron, the magnetic domains of the iron begin to line up along the magnetic field (green lines). Most of the magnetic domains of iron quickly align along the magnetic field lines. As a result, the iron itself becomes a permanent magnet.
Magnetic effect
Today it is obvious that the matter is not in miracles, but in a more than unique characteristic of the internal structure of the electronic circuits that form magnets. An electron that constantly rotates around an atom forms the same magnetic field.
Microatoms have a magnetic effect and are in complete equilibrium, but magnets, with their attraction, influence some types of metals, such as iron, nickel, cobalt.
These metals are also called ferromagnets. In close proximity to a magnet, atoms immediately begin to rearrange and form magnetic poles.
Atomic magnetic fields exist in an ordered system; they are also called domains. In this characteristic system there are two poles opposite to each other - north and south.
Application
The north pole of a magnet attracts the south pole, but two identical poles immediately repel each other.
Modern life without magnetic elements is impossible, because they are found in almost all technical devices, including computers, televisions, microphones, and much more. In medicine, magnets are widely used in examinations of internal organs and in magnetic therapy.
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The material uses photos and excerpts from:
http://information-technology.ru/sci-pop-articles/23-physics/231-pochemu-magnit-prityagivaet-zhelezo
http://www.kakprosto.ru/kak-821401-pochemu-magnit-prityagivaet-zhelezo
http://www.voprosy-kak-i-pochemu.ru/pochemu-magnit-prityagivaet-ili-vse-o-magnitnyx-polyax/
http://log-in.ru/articles/pochemu-magnit-ne-vse-prityagivaet/
Source: https://magnet-prof.ru/index.php/pochemu-magnit-prityagivaet-ili-vse-o-magnitnyih-polyah.html
Perendeva magnetic engine: one step closer to the dream of a perpetual motion machine
January 17, 2020
The discovery of the phenomenon of permanent magnets had many positive consequences for world science and economics, opening up the opportunity for engineers to create unique mechanisms for electrical devices.
But those who prefer to look into the distant future saw in the new technology a real chance to glorify their name forever by creating the dream of mankind - a perpetual motion machine. One of them, engineer from South Africa Michael Brady, managed not only to calculate, but also to assemble such a device, present it to a wide audience and obtain a patent for his own invention.
More than 50 years have passed, and advanced minds are still trying to implement his plan at home or in an industrial environment, assembling Perendev’s proprietary engine with their own hands.
Some historical facts
The first attempt to construct a magnetic perpetual motion machine was made in the middle of the last century. The year 1969 was a turning point for this direction of scientific thought: a fully operational motor was presented to the public, the cycle of which was finite, but significantly different from other models in the duration of action. The justification for this was the weak magnets involved in the design and the high friction force, which extinguished the useful energy of the device.
Deciding to bask in the rays of capricious glory on the wave of general enthusiasm, specialist Michael Brady from Africa managed to design a working 6 kW engine.
To dispel any doubts about his ingenuity and ingenuity, he made a video about his own alternative Perendeva engine and posted it on the Internet, where millions of service users were able to familiarize themselves with the development.
Either they were intoxicated by what they saw and gave free rein to their dreams, or the inventor was able to skillfully deceive the audience, but the development was a dizzying success.
Taking this opportunity, Brady initiated a fundraiser for the production of Perendev generator sets of 100 and 300 kW, which would be enough for the uninterrupted operation of large-scale production. A million dollars is not bad for a startup, even if it’s just another soap bubble.
With an impressive sum, the savvy engineer managed to move to Switzerland and declared himself bankrupt in order to spend the rest of his days in luxury and a comfortable life. However, soon a criminal trial was launched against the would-be inventor, where the word “fraudster” was said to the main character.
Until now, its discovery excites inquiring minds, and attempts to create a Perendev engine using magnets are actively discussed on thematic forums.
Operating principle and design of the Perendeva magnetic motor
In fact, magnetic devices may well become the prototype of a real perpetual motion machine. They practically do not need energy, coming into motion due to the force of attraction and repulsion.
But the starting impulse must be provided by an external source of energy, which contradicts the basic principle of a perpetual motion machine—autonomy of operation.
Today's popular office trinkets in the form of colliding magnetized balls on a thin wire or “swimming” dolphins embody the principle of operation of such a mechanism, but are powered by a regular coin cell battery.
The first person who managed to create a prototype of a perpetual motion machine was Nikola Tesla. But even his device was not ideal, since it began to work only from an electrical impulse. The Brady engine continues this idea. By eliminating the friction force, which consumes a significant part of the device’s efficiency, he tries to increase the coefficient to 100%.
Elements and assembly of the Perendeva engine
The main components of the model are presented in the diagram:
1 — Section of power lines 2 — Rotating rotor 3 — Stator located outside the magnetic field
4 - ring-shaped permanent magnet
5 - Flat-shaped permanent magnets
6 - Metal case outside the influence of the magnetic field
You can use a ball from a bearing as a rotor, and install a loudspeaker element in place of the ring magnet. The poles of a permanent magnet are on both planes. It is limited by barrier rings made of materials that are not subject to magnetization. A steel ball is placed between the rings to act as a rotating rotor. It is attracted to a magnet due to the interaction of opposite poles.
The stator of the Perendev magnetic motor is a shielded metal plate. Small flat magnets are attached to it, focusing on the dimensions of the ring magnet. As the ball approaches the stator, attractive and repulsive forces alternately arise in the magnets, launching the rotor along the trajectory of the ring magnet. As long as the electromagnetic properties of the elements remain at a high level, the rotation of the ball is ensured.
Useful tips, Perendeva engine diagram and assembly information can be clarified by watching the following video:
Prospects for further improvements to the Perendeva magnet engine
Skeptics, who have a fair amount of doubt about high-profile inventions, argue that it is impossible to create a perpetual motion machine. In their authoritative opinion, the constant production of energy from nowhere is impossible either from the point of view of science or from the standpoint of common sense. However, with regard to the magnetic field, it is worth making exceptions: this is a special type of matter with a density of up to 280 kJ/cub.m, within which physical laws apply.
The specified value is enough to safely count on obtaining the energy potential to start and operate the engine. This is confirmed by numerous scientific works and patented inventions. But the operating mechanisms, unfortunately, are still present only in the dreams of inventors or are kept in strict secrecy.
It may not be possible to see them in action: after a few decades, even a strong magnet will lose its strength, and the motor will turn out to be a useless piece of metal.
Source: https://altenergiya.ru/novosti/magnitnyj-dvigatel-perendeva-na-shag-blizhe-k-mechte-o-vechnom-dvigatele.html
Why aluminum is not magnetic - Metals, equipment, instructions
Any child knows that metals are attracted to magnets. After all, they have more than once hung magnets on the metal door of the refrigerator or letters with magnets on a special board. However, if you put a spoon against a magnet, there will be no attraction. But the spoon is also metal, so why does this happen? So, let's find out which metals are not magnetic.
Scientific point of view
To determine which metals are not magnetic, you need to find out how all metals in general can relate to magnets and a magnetic field. With respect to the applied magnetic field, all substances are divided into diamagnetic, paramagnetic and ferromagnetic.
Each atom consists of a positively charged nucleus and negatively charged electrons. They move continuously, which creates a magnetic field. The magnetic fields of electrons in one atom can enhance or cancel each other, depending on the direction of their movement. Moreover, the following can be compensated:
- Magnetic moments caused by the movement of electrons relative to the nucleus are orbital.
- Magnetic moments caused by the rotation of electrons around their axis are spin moments.
If all magnetic moments are equal to zero, the substance is classified as diamagnetic. If only spin moments are compensated - to paramagnets. If the fields are not compensated, use ferromagnets.
Paramagnets and ferromagnets
Let's consider the option when each atom of a substance has its own magnetic field. These fields are multidirectional and compensate each other. If you place a magnet next to such a substance, the fields will be oriented in one direction. The substance will have a magnetic field, a positive and a negative pole.
Then the substance will be attracted to the magnet and can itself become magnetized, that is, it will attract other metal objects. For example, you can magnetize steel clips at home. Each one will have a negative and a positive pole, and you can even hang a whole chain of paper clips on a magnet.
Such substances are called paramagnetic.
Ferromagnets are a small group of substances that are attracted to magnets and are easily magnetized even in a weak field.
Diamagnets
In diamagnetic materials, the magnetic fields inside each atom are compensated.
In this case, when a substance is introduced into a magnetic field, the movement of electrons under the influence of the field will be added to the natural movement of electrons.
This movement of electrons will cause an additional current, the magnetic field of which will be directed against the external field. Therefore, the diamagnetic material will be weakly repelled from the nearby magnet.
So, if we approach the question from a scientific point of view, which metals are not magnetic, the answer will be – diamagnetic.
Distribution of paramagnets and diamagnets in the periodic table of Mendeleev elements
The magnetic properties of simple substances change periodically with increasing atomic number of the element.
Substances that are not attracted to magnets (diamagnets) are located mainly in short periods - 1, 2, 3. Which metals are not magnetic? These are lithium and beryllium, and sodium, magnesium and aluminum are already classified as paramagnetic.
Substances that are attracted to magnets (paramagnets) are located mainly in the long periods of the Mendeleev periodic system - 4, 5, 6, 7.
However, the last 8 elements in each long period are also diamagnetic.
In addition, three elements are distinguished - carbon, oxygen and tin, the magnetic properties of which are different for different allotropic modifications.
In addition, there are 25 more chemical elements whose magnetic properties could not be established due to their radioactivity and rapid decay or the complexity of synthesis.
The magnetic properties of lanthanides and actinides (all of which are metals) change irregularly. Among them there are para- and diamagnetic materials.
There are special magnetically ordered substances - chromium, manganese, iron, cobalt, nickel, the properties of which change irregularly.
What metals are not magnetic: list
There are only 9 ferromagnets, that is, metals that are highly magnetic, in nature. These are iron, cobalt, nickel, their alloys and compounds, as well as six lanthanide metals: gadolinium, terbium, dysprosium, holmium, erbium and thulium.
Metals that are attracted only to very strong magnets (paramagnetic): aluminum, copper, platinum, uranium.
How to solder aluminum with a torch
Since in everyday life there are no such large magnets that would attract a paramagnetic material, and also no lanthanide metals are found, we can safely say that all metals except iron, cobalt, nickel and their alloys will not be attracted to magnets.
So, what metals are not magnetic to a magnet:
- paramagnetic materials: aluminum, platinum, chromium, magnesium, tungsten;
- diamagnetic materials: copper, gold, silver, zinc, mercury, cadmium, zirconium.
In general, we can say that ferrous metals are attracted to a magnet, non-ferrous metals are not.
If we talk about alloys, then iron alloys are magnetic. These primarily include steel and cast iron. Precious coins can also be attracted to a magnet, since they are not made of pure non-ferrous metal, but of an alloy that may contain a small amount of ferromagnetic material. But jewelry made of pure non-ferrous metal will not be attracted to a magnet.
What metals do not rust and are not magnetic? These are ordinary food grade stainless steel, gold and silver items.
Source: https://spb-metalloobrabotka.com/pochemu-alyuminiy-ne-magnititsya/
Metals that are not magnetic - Metals and their processing
Probably everyone had to hold in their hands a piece of jewelry or another object, obviously metal.
But how can you determine what metal is used in production? It could be a precious material or a counterfeit, or even a trinket with no claims to value. Expertise from specialists will give you the exact answer, but it is not free.
But there are methods for approximately determining the type of metal at home. They were used a long time ago, but they have not lost their relevance in our time.
Magnet check
Bringing a magnet close to the item being tested is a good way to perform initial testing. By the reaction of the magnet you can determine which group the metal belongs to:
- Ferromagnets. The magnet is clearly attracted to the object, which means that the product may contain iron, steel or nickel.
- Paramagnetic materials. The interaction with the magnet is very weak. This group includes aluminum and chrome. Precious metals that are paramagnetic are platinum, palladium and silver.
- Diamagnets. In general, they do not react to magnets. Copper and zinc have these properties. Precious metals - gold.
Magnet check
Of course, such a check will not allow us to accurately determine the material from which the item is made. After all, a non-magnetic metal may not be in its pure form, but in the form of an alloy with a ferromagnet. But it can confirm or refute the assumption. For example, if it is checked whether it is gold or not, but the item is clearly magnetic, then it can be argued that it is a fake.
When checking jewelry, you should take into account that, in addition to precious metals, they may contain clasps, built-in springs, made of another material. You need to check the metal itself.
Heat check
You can also determine the group of a metal by how it conducts heat. It is known that the thermal conductivity of silver is very high. It is almost five times higher than that of iron or platinum. Slightly worse for gold, copper and aluminum. Platinum transfers heat even weaker than iron.
If you immerse the metal in hot water for 15–20 seconds, then based on its temperature, determined by touch, you can draw some conclusions.
- Gold and silver objects will become as hot as the water in which they were dipped.
- During this time, platinum and items containing iron will become warm, but not hot.
In this way it is easy to distinguish platinum from silver. But it’s not possible to compare silver or aluminum alloy.
Iodine test
You can check the authenticity of the metal using an iodine solution purchased at a pharmacy. A drop of iodine is applied to the surface and left for several seconds. Iodine will not harm noble metals - gold, platinum, silver. If the color of a drop of iodine does not change, and after removing it with a napkin, no traces or stains remain, this indicates the authenticity of the metal. If darkening is visible at the place of the drop, then this is a low-quality alloy or an outright fake.
Iodine testing of gold
Vinegar test
Household vinegar solution also does not affect precious metals. And it is dangerous for counterfeits. But, unlike the iodine test, acetic acid takes time. To wait for the result, you need to immerse the metal being tested in a container with vinegar for 15–30 minutes. The absence of traces of interaction between metal and vinegar is a sign of nobility.
If, in addition to metal, the product contains precious or semi-precious stones, then it is better not to check them this way; vinegar can ruin them. This is especially true for pearls.
Dental check
From novels and films we know that they used to test the authenticity of gold coins by biting them. What exactly can be installed in this “old-fashioned” way? Gold is a soft metal. Therefore, even with a weak bite, a dent from the teeth remains on it. Fake alloys do not have this property; you cannot take them with your teeth.
Such a test gives good results for high-quality products. The higher the pure gold content, the softer it is. Gold of 900 purity and higher is so soft that they try not to expose valuable items made from it to contact with other objects.
This is how you can compare platinum and silver. The latter does not have the softness of gold, but a strong bite may leave a small dent. It is impossible to leave marks with teeth on real platinum.
Application of chemicals
Testing with active chemical reagents should be left as a last resort. If handled improperly, they will damage even genuine precious metal. And they can be dangerous for the health of the inspector.
Ammonia
Pure gold does not react to ammonia. But practically no products intended for use are made from gold 900 and 999, only for collections. And on a precious metal of lesser purity, ammonia can leave an irremovable mark. Its solution in combination with other substances is used to clean gold items. Therefore, it is not worth identifying gold and silver items using ammonia.
Platinum products are usually produced with a high purity. Therefore, you can check the authenticity of platinum with ammonia. This chemical will not leave a mark on her.
Nitric and hydrochloric acids
Separately, these acids do not affect high-grade gold and platinum. And if you mix their concentrated solutions in a ratio of 1:3, you get a mixture called aqua regia. It can even dissolve gold. Aqua regia does not “take on” platinum when it is cold. This precious metal will gradually dissolve in the heated mixture.
Oddly enough, royal vodka is not afraid of genuine silver. It reacts to it by forming silver chloride in the form of a thin film on the surface. The latter protects the product itself from destruction.
Density check
One of the reliable ways to determine the type of metal or alloy is to determine its density. For pure gold it is two times higher than for copper and almost three times higher than for iron. Platinum is even heavier than gold. Even an alloy of 585 gold is noticeably heavier than base metals.
Of course, to determine the exact density of a small product you will need pharmaceutical scales, volume calculations (Archimedes' law to help) and tabular data on the density of base metals. But to solve the question of what the alloy is mainly made of, gold or another metal, rough estimates are sufficient. If you have at hand an object made of obviously genuine metal of approximately equal volume, then you may not even need a scale. A weight difference of two to three times is not so difficult to catch.
Separately, each of the considered methods will not give an exact answer to the question of what metal the product is made of. But if several different tests show the same results, you can be confident in the correct determination. If not, then you will have to turn to professionals.
Source: https://magnetline.ru/metally-i-splavy/metally-kotorye-ne-magnityatsya.html
What types of metals are attracted to magnets? - Articles
Something is considered magnetic when it can attract or repel another magnetic object. Magnets are characterized by their atomic composition, with their electrons arranged so that positive electrons point in one direction and negative electrons point in the opposite direction. Most metals contain some level of magnetism, but they vary in strength.
Most metals contain some level of magnetism, however they vary in strength (Photodisc/Photodisc/Getty Images)
Types of magnets
There are two main types of magnets: permanent magnets, which once they are magnetized, maintain a level of magnetism, and temporary magnets, which exhibit permanent magnetic qualities when they are in a strong magnetic field.
Metal clamps are an example of a temporary magnet (Image Flickr.com, courtesy of Brandon Baunach)
Magnet classes
Magnets are placed in four different classes, all exhibiting different characteristics. The four main metals used to make permanent magnets are neodymium-iron-boron, samarium-cobalt, alnico and ferrite.
coins
Old American, Canadian, English, Chinese, Japanese and German pennies contain a high percentage of pure metal. Coins with high copper, silver or nickel content are attracted to magnets.
Old copper coins are magnetic (Hemera Technologies / AbleStock.com / Getty Images)
iron
Iron and steel products such as nails and screws, kitchen sinks and cutlery are attracted by permanent magnets.
Many screws and hardware are magnetic (Image credit: Flickr.com, courtesy of Douglas Heriot)
Brass and bronze
Brass and brass products that are attracted to magnets include household fixtures such as metal door legs or special screws.
Fixed brass fittings are magnetic (Image courtesy of Flickr.com, courtesy of Ben Zwan)
Magnetizing and demagnetizing objects
To temporarily magnetize a metal object, tap or rub it with a magnet, or pass an electric current through it. To demagnetize a temporary magnet, throw metal under a non-metallic surface such as linoleum.
Source: https://ru.laermfeuer.org/tipos-metais-atraidos-imas-fatos_93302-12490
How to distinguish copper from other metals
For most of us, knowledge about copper and its properties is limited to a school chemistry course, which is quite enough at the everyday level.
However, sometimes there is a need to reliably determine whether a material is a pure element, an alloy, or even a composite material.
The opinion that this information is needed only by those who are engaged in the acceptance or delivery of scrap metal is erroneous: for example, on amateur radio forums, topics are often raised about how to distinguish copper in wires from copper-plated aluminum.
Briefly about element No. 29
Pure copper (Cu) is a golden-pink metal with high ductility, thermal and electrical conductivity. Chemical inertness in an ordinary non-aggressive environment is ensured by a thin oxide film, which gives the metal an intense reddish tint.
The main difference between copper and other metals is color . In fact, there are not so many colored metals: only gold, cesium and osmium are similar in appearance, and all elements included in the group of non-ferrous metals (iron, tin, lead, aluminum, zinc, magnesium and nickel) have a gray color with varying intensity of shine.
An absolute guarantee of the chemical composition of any material can be obtained only through spectral analysis. The equipment for carrying it out is very expensive, and even many expert laboratories can only dream of it. However, there are many ways to distinguish copper at home with a high degree of probability.
1. Determination by color
So, we have before us a piece of unknown material that needs to be identified as copper. The emphasis on the term “material” rather than “metal” was made specifically, since recently many composites have appeared that are very similar to metals in appearance and tactile sensations.
First of all, we consider color. It is advisable to do this in daylight or “warm” LED lighting (under “cool” LEDs, the reddish tint changes to yellow-green). It is ideal if there is a copper plate or wire for comparison - in this case, errors in color perception are practically eliminated.
Important: old copper products can be covered with an oxidized layer (a greenish-blue loose coating): in this case, the color of the metal must be looked at in a cut or saw cut.
2. Determination by magnet
Color matching is a reliable but not sufficient method of identification. The second step of independent experiments will be a test with a magnet. Chemically pure copper is classified as diamagnetic - i.e. to substances that do not respond to magnetic influence.
If the material under study is attracted to a magnet, then it is an alloy in which the content of the main substance is no more than 50%.
However, even if the sample did not react to the magnet, it is too early to rejoice, since often an aluminum base is hidden under the copper coating, which is also not magnetic (this can be eliminated by filing or cutting).
3. Determination by reaction to flame
Another way to identify copper is to heat a sample over an open fire (gas stove, lighter or regular match). When heated, copper wire will first lose its shine and then turn black-brown, covered with oxide. This method can also be used to cut off composite materials that, when heated, begin to smoke and form a gas with a pungent odor.
4. Determination through chemical experiments
The reaction with concentrated nitric acid is indicative: if the latter is dropped onto the surface of a copper product, a green-blue color will occur.
A qualitative reaction to copper is dissolution in hydrochloric acid followed by exposure to ammonia. If a copper sample is left in an HCl solution until completely or partially dissolved, and then ordinary pharmaceutical ammonia is dropped into it, the solution will turn intensely blue.
Important: working with chemicals requires precautions. Independent experiments should be carried out in a well-ventilated area using personal protective equipment (rubber gloves, apron, goggles).
How to distinguish between copper and its alloys?
Copper alloys are widely used in industry. Over many years of research, it has been possible to obtain many materials with unique properties: high ductility, electrical conductivity, chemical resistance, strength (all depends on alloying additives). The most common are bronze (with the addition of tin, aluminum, silicon, manganese, lead and beryllium), brass (with the addition of 10-45% zinc), as well as copper-nickel alloys (nickel silver, cupronickel, copel, manganin).
Only bronze and brass are difficult to identify, since copper-nickel alloys differ significantly in color due to their low copper content.
Copper or brass?
Brass can contain from 10 to 45% zinc, a silver-gray metal. Naturally, the more zinc, the paler the alloy. However, high-copper brasses, in which the amount of additives does not exceed 10%, differ little in color from the copper sample.
In this case, you can only trust your feelings: brass is much harder and more difficult to bend (for greater reliability, a comparison with a reference sample is advisable). You can try to remove the shavings: copper shavings will have a curl shape, brass shavings will be straight, needle-shaped.
When the samples are placed in a solution of hydrochloric acid, no reaction with copper is observed, and a white coating of zinc chloride forms on the surface of the brass.
Copper or bronze?
Like brass, bronze is much stronger, which is explained by the presence of harder metals in the alloy. The most reliable test will be a “tooth test” - there is unlikely to be a trace of pressure left on the surface of the bronze.
You can also experiment with a hot saline solution (200 g of table salt per 1 liter of water). After 10-15 minutes, a copper sample will acquire a more intense shade than a bronze one.
For those familiar with electrical engineering
Very often, copper cores from electrical cables are sold as scrap non-ferrous metals, and there are often cases when copper-coated aluminum is used in the production of electrical products. This material has a significantly lower density, but due to its irregular geometric shape, determining the volume to calculate the density is quite difficult.
In this case, copper can be determined by electrical resistance (of course, if you have the appropriate instruments - a voltmeter, ammeter, rheostat). We measure the cross-section and length of the core, take instrument readings, and Ohm’s law will help you.
Resistivity is a fairly accurate characteristic by which any metal can be identified with a high degree of reliability.
Conclusion
It is possible to accurately determine the quality of copper scrap or the content of the main substance in the alloy only after an examination: all of the above methods are approximate. If we consider pricing when purchasing scrap metal, the most expensive is electrical copper, the cheapest are alloys of the brass group. The final cost of the transaction can be clarified with the managers of companies involved in the purchase of scrap non-ferrous metals.
Source: https://blog.blizkolom.ru/kak-otlichit-med
What is the name of a metal that is not attracted to a magnet?
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Question for experts: what metal does not attract a magnet?
Best regards, Marina Sivtsova
Best answers
Any diamagnetic material does not attract a magnet, but rather repel it. These are, for example, diamagnetic metals such as Cu-copper, Au-gold, Zn-zinc, Hg-mercury, Ag-silver, Cd-cadmium, Zr-zirconium, etc.
But paramagnetic metals, such as Aluminum, are attracted to a magnet. It’s just that when they are not in the ferromagnetic phase, such attraction is very weak and unnoticeable without instruments. A typical example is aluminum.
At room temperature it is not in the ferromagnetic phase, but in the ordinary paramagnetic phase. Therefore, if you simply hold it with your hands and bring it to a magnet, you will not feel the attraction.
But if you hang a piece of aluminum next to a magnet on a long thread, the thread will deviate slightly from the vertical.
Magnet does not attract aluminum
It’s easier to answer which one attracts - only iron
A magnet does not attract any non-magnetic metal.
They attract only 4 or 5 - Iron, Nickel, Cobalt. Gadolinium (from +16g). Dysprosium (with a large minus) - the rest are not magnetic - come into question, except for them, write out all the metals from the periodic table. Be careful with rare earths - they may also advise that this is nonsense. It’s difficult with alloys - refer to the Textbook “Metal Science” - author Gulyaev A.P.
Copper, aluminum and alloys based on these metals
And also gold and silver)))
Everything except ferromagnets.
answer
This video will help you figure it out
Answers from experts
There are no non-magnetic metals! Any metal is either attracted by the magnetic field of a magnet (called paramagnets) or repelled by the magnetic field of a magnet (called diamagnetic). There is no third. If you consider non-magnetic metals to be those that are not attracted by a magnet (that is, repelled), then these are all diamagnetic metals: copper, silver, gold, etc.
Among the paramagnetic metals, there are those that at room temperatures are in the ferromagnetic phase and in the ferrimagnetic phase (they are called ferrites). They stand out among other paramagnetic materials in that their attraction to a magnet is noticeable at the everyday level without any equipment.
If you hold a magnet and some ferromagnetic material (for example, iron) or ferrite in your hands, you will feel that they are attracted to each other. And if the paramagnetic is not in the ferro- or ferrimagnetic phase, then such an attraction to the magnet at the everyday level cannot be felt with your hands.
For example, to see that aluminum is attracted to a magnet, you need to hang them side by side by long threads and measure the angle of deviation of the threads from the vertical. The threads will become slightly non-parallel.
The repulsion of a magnet from diamagnetic materials is even weaker. Here we need precise instruments and very microscopic light samples.
There are only four magnetic metals: iron (and its alloys), cobalt, nickel and gadolinium.
All other metals: copper, aluminum, etc. are non-magnetic and are not attracted by a magnet.
When starting the engine, does it run (noisy) and the contacts of the starter are not attracted? The starter works without a motor (new 4 values), but when starting the voltage drops to 230-170V
copper and magnet:
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All metals are divided into paramagnetic and diamagnetic.
Diamagnets are repelled by a magnet. The effect is very weak and is not noticeable at home without devices. Diamagnets include, for example, copper, gold, silver, etc.
Paramagnets can have different magnetic states.
In the paramagnetic phase, paramagnetic substances are weakly attracted to the magnet.
The effect is very weak and not noticeable in everyday life. You need to hang a piece of metal on a long thread and bring a magnet to it, then you will notice that the thread deviates slightly from the vertical. At room temperature, a paramagnetic substance such as aluminum is in the paramagnetic phase.
In addition to the paramagnetic phase, paramagnetic substances can also be in various other phases depending on their temperature.
Among these phases there are two very interesting phases, these are the ferromagnetic phase and the ferrimagnetic phase. In these phases, paramagnetic substances are very strongly attracted to magnets. At room temperature, such a ferromagnetic phase contains paramagnetic materials such as iron, cobalt, nickel, etc., as well as a bunch of ferrite alloys.
A paramagnetic metal such as gadolinium at temperatures above +19 degrees is in the paramagnetic phase and is therefore weakly attracted to a magnet. When it is cooled below +19 degrees, it enters the ferromagnetic phase and begins to be more strongly attracted to the magnet. The lower the temperature, the stronger the attraction to the magnet.
For dysprosium, such a critical temperature will be -185 degrees, that is, at room temperature it is not ferromagnetic and is weakly attracted to a magnet.
And for iron this is a temperature of 70 degrees. If you heat iron to such a temperature, it goes into the paramagnetic phase and is very weakly attracted to the magnet, unnoticeable without instruments.
aluminum copper silver gold magnesium zinc
It depends on how it beckons. Most metals (potassium, calcium, ruidium mercury) are not attracted to the constant. A small amount of “ferromagnets” Fe, Co, Ni, Gd, Tb, Dy, Ho, Er and a bunch of alloy compounds are attracted. There are also non-metals Chromium (IV) oxide and some others.
For most metal lattices the exchange integral is negative. Therefore they are not ferromagnetic. Yuri Semykin listed metals that have ferromagnetic properties. The rest are not ferromagnetic.
Source: https://dom-voprosov.ru/prochee/kak-nazyvaetsya-metall-kotoryj-ne-prityagivaetsya-k-magnitu
Why does a magnet attract - all about magnetic fields
Why does a magnet attract?
Magnets, like the toys stuck to your refrigerator at home or the horseshoes you were shown in school, have several unusual features. First of all, magnets are attracted to iron and steel objects, such as the door of a refrigerator. In addition, they have poles.
Bring two magnets closer to each other. The south pole of one magnet will be attracted to the north pole of the other. The north pole of one magnet repels the north pole of the other.
Magnetic and electric current
The magnetic field is generated by electric current, that is, by moving electrons. Electrons moving around an atomic nucleus carry a negative charge. The directed movement of charges from one place to another is called electric current. An electric current creates a magnetic field around itself.
Magnetic field lines
This field, with its lines of force, like a loop, covers the path of electric current, like an arch that stands over the road.
For example, when a table lamp is turned on and a current flows through the copper wires, that is, the electrons in the wire jump from atom to atom and a weak magnetic field is created around the wire.
In high-voltage transmission lines, the current is much stronger than in a table lamp, so a very strong magnetic field is formed around the wires of such lines. Thus, electricity and magnetism are two sides of the same coin - electromagnetism.
Related materials:
Gravitational interaction
Electron movement and magnetic field
The movement of electrons within each atom creates a tiny magnetic field around it. An electron moving in orbit forms a vortex-like magnetic field. But most of the magnetic field is created not by the movement of the electron in orbit around the nucleus, but by the movement of the electron around its axis, the so-called spin of the electron. Spin characterizes the rotation of an electron around an axis, like the movement of a planet around its axis.
Why materials are magnetic and not magnetic
In most materials, such as plastics, the magnetic fields of individual atoms are randomly oriented and cancel each other out. But in materials like iron, the atoms can be oriented so that their magnetic fields add up, so a piece of steel becomes magnetized. Atoms in materials are connected in groups called magnetic domains. The magnetic fields of one individual domain are oriented in one direction. That is, each domain is a small magnet.
Different domains are oriented in a wide variety of directions, that is, randomly, and cancel each other's magnetic fields. Therefore, a steel strip is not a magnet. But if we manage to orient the domains in one direction so that the forces of the magnetic fields add up, then watch out! The steel strip will become a powerful magnet and will attract any iron object from a nail to a refrigerator.
Interesting fact: the mineral iron ore is a natural magnet. But still, most magnets are made artificially.
What force can force atoms to line up to form one large domain? Place the steel strip in a strong magnetic field. Gradually, one by one, all domains will turn in the direction of the applied magnetic field. As the domains rotate, they will draw other atoms into this movement, increasing in size, literally swelling. Then the identically oriented domains will connect, and lo and behold, the steel strip has turned into a magnet.
Related materials:
How are magnets made?
You can demonstrate this to your comrades using an ordinary steel nail. Place the nail in the magnetic field of a large horseshoe magnet. Hold it there for a few minutes until the nail domains line up in the desired direction. Once this happens, the nail will briefly become a magnet. With its help you can even pick up fallen pins from the floor.
Source: https://kipmu.ru/pochemu-magnit-prityagivaet-ili-vse-o-magnitnyx-polyax/
What metals are not magnetic and why?
Any child knows that metals are attracted to magnets. After all, they have more than once hung magnets on the metal door of the refrigerator or letters with magnets on a special board. However, if you put a spoon against a magnet, there will be no attraction. But the spoon is also metal, so why does this happen? So, let's find out which metals are not magnetic.
Impossible things that physicists made possible
In the strange world of physics, the impossible is always possible.
But recently, many scientists have managed to surpass even this statement and achieve what previously seemed completely incredible.
Let's see.
1. Cold cold
Miracles of physics: cold cold.
In the past, scientists were unable to cool an object to temperatures below the so-called “quantum limit.” To freeze something with a laser, you need to slow down the atoms of that substance and their heat-generating vibrations, but until now it has not been possible to reduce the temperature below the quantum limit.
Only now have physicists managed to develop a drum made of vibrating aluminum and reduce its temperature to 360 microKelvin, which is 10,000 times lower than temperatures in the depths of space. This achievement could one day play a role in the development of ultrafast electronics and help unravel the behavior of particles in the quantum world.
2. The brightest light
Miracles of physics: the brightest light.
The brilliance of our own Sun is already worthy of attention. Now you just have to imagine the combined light of a billion suns. We are talking about the equivalent of what physicists recently “awakened to life” in the laboratory. It was officially the brightest light ever recorded on Earth, but unusually, the light also behaved in unexpected ways. He changed the appearance of objects.
3. Molecular black hole
Miracles of physics: the molecular black hole.
A group of physicists recently created something that behaved like a black hole. They used the most powerful X-ray laser in history, the Linac Coherent Light Source (LCLS), to break up the iodomethane and iodobenzene molecules.
The researchers expected that the beam would “knock out” most of the electrons from the atom of the iodine molecule, leaving a vacuum in their place. In experiments with weaker lasers, this void was then filled with electrons from the outer part of the atom.
But when the LCLS turned on, something amazing happened.
Instead of being reduced on its own, the iodine atom began to “devour” electrons from neighboring hydrogen and carbon atoms. It looked like a tiny black hole inside a molecule. The cycle was repeated until the entire molecule exploded. The iodine atom was the only atom that behaved this way.
4. Metallic hydrogen
Miracles of physics: metallic hydrogen.
It has been called the “holy grail of high-pressure physics,” but so far no scientist has succeeded in creating metallic hydrogen. As a possible superconductor, it is a highly sought-after form of an element that normally is a gas. The possibility of turning hydrogen into a metal was first proposed in 1935.
Physicists suggested that mass pressure could cause such a transformation, but the problem was that the technology did not allow such strong pressure to be achieved. In 2017, an American team modified the old technology and conducted preliminary experiments for the first time inside a device called a diamond press cell. The device was able to produce a staggering pressure: about 500,000 MPa.
5. Computer chip with brain cells
Miracles of physics: a computer chip with brain cells.
When it comes to the development of electronics, scientists speculate that light may one day replace electricity. Physicists realized the potential of light in this regard decades ago, when it became clear that its waves could travel parallel to each other and thus perform several tasks at once. Traditional electronics rely on transistors, but recently a computer chip has been invented that mimics the human brain.
It "thinks" quickly using beams of light that interact with each other in a similar way to neurons. In the past, simpler neural networks were created, but the hardware for them took up several cabinets. It was considered impossible to create anything smaller. However, scientists were able to make a new chip from silicone, the size of which is only a couple of millimeters.
6. Impossible form of matter
Miracles of physics: the impossible form of matter.
This bizarre material has the rigid crystalline structure inherent in solids, while at the same time being a liquid. This paradox was intended to remain unrealized because it contradicts known physics.
However, in 2016, two independent scientific groups made a material called "superfluid solid." Swiss and American scientists created something similar using lasers, which changed the density of atoms in a liquid substance until a crystalline structure appeared in it.
7. Liquid with negative mass
Miracles of physics: liquid with negative mass.
In 2017, physicists developed something mind-blowing: a form of matter that is attracted to a force that repels it. Positive mass is the norm that most people are used to: if you push something, the object will accelerate in the direction in which it is pushed. But for the first time, a liquid was created that behaves differently from everything else in this world, but was made from a frozen Bose-Einstein condensate of rubidium atoms irradiated by lasers.
8. Time crystals
Wonders of physics: time crystals.
When Frank Wilczek, a Nobel Prize-winning physicist, proposed the idea of time crystals, his theory seemed crazy—especially the part that involved reproducing perpetual motion in the so-called “ground state,” the lowest energy level in matter. Movement is theoretically impossible, because it requires energy, but there is almost none.
Wilczek believed that perpetual motion could be achieved by changing the ground state of an atom in a crystal from stationary to periodic. This atomic structure of an object repeats itself over time, allowing for constant “switching” without the need for energy. This defied the laws of physics, but in 2017, five years after Vilczek foresaw it, physicists made the first “time crystals,” managing to rotate nitrogen impurities in diamond.
9. Bragg mirrors
Miracles of physics: Bragg mirrors.
A Bragg mirror can't reflect much because it's only 1,000 to 2,000 atoms in size. But it can reflect light, making it useful in places where tiny mirrors are needed, such as in modern electronics. This “mirror” has a conventional shape: atoms hang in a vacuum, resembling a chain of beads.
In 2011, a group of German physicists created the most reflective mirror to date (80 percent) by assembling ten million atoms into a lattice structure. Since then, the Danish and French teams have significantly reduced the number of atoms needed. Instead of binding atoms grouped together, they strung them in a row onto microscopic optical fibers.
Apart from promising limitless advances in technology, this could one day prove useful in quantum devices as atoms additionally used a light field to interact with each other.
10. 2-D magnet
Miracles of physics: 2-D magnet.
Physicists have been trying to create a two-dimensional magnet since the 1970s, but have always met with failure. A true 2-D magnet should retain its magnetic properties even after being stripped down to a state that makes it two-dimensional—a layer just one atom thick. Scientists began to doubt whether such a magnet was possible.
In June 2017, in another attempt to create a 2-D magnet, researchers experimented with chromium triiodide. They created the world's first real two-dimensional magnet, and at a surprisingly warm temperature (“only” -228 degrees Celsius).
Currently the magnet does not work at room temperature and oxygen damages it. Despite their fragility, 2-D magnets will allow physicists to complete experiments that were considered impossible until now.
Source: https://vseonauke.com/1864414630923208932/nevozmozhnye-veschi-kotorye-fiziki-sdelali-vozmozhnymi/
IT News
Date Category: Physics
When a magnet attracts metal objects to itself, it seems like magic, but in reality the “magical” properties of magnets are associated only with the special organization of their electronic structure. Because an electron orbiting an atom creates a magnetic field, all atoms are small magnets; however, in most substances the disordered magnetic effects of atoms cancel each other out.
The situation is different in magnets, the atomic magnetic fields of which are arranged in ordered regions called domains. Each such region has a north and south pole. The direction and intensity of the magnetic field is characterized by the so-called lines of force (shown in green in the figure), which leave the north pole of the magnet and enter the south.
The denser the lines of force, the more concentrated the magnetism. The north pole of one magnet attracts the south pole of another, while two like poles repel each other. Magnets attract only certain metals, mainly iron, nickel and cobalt, called ferromagnets.
Although ferromagnetic materials are not natural magnets, their atoms rearrange themselves in the presence of a magnet in such a way that the ferromagnetic bodies develop magnetic poles.
Magnetic chain
Touching the end of a magnet to metal paper clips creates a north and south pole for each paper clip. These poles are oriented in the same direction as the magnet. Each paper clip became a magnet.
Countless little magnets
Some metals have a crystalline structure made up of atoms grouped into magnetic domains. The magnetic poles of the domains usually have different directions (red arrows) and do not have a net magnetic effect.
Formation of a permanent magnet
- Typically, iron's magnetic domains are randomly oriented (pink arrows), and the metal's natural magnetism does not appear.
- If you bring a magnet (pink bar) closer to the iron, the magnetic domains of the iron begin to line up along the magnetic field (green lines).
- Most of the magnetic domains of iron quickly align along the magnetic field lines. As a result, the iron itself becomes a permanent magnet.
Source: http://Information-Technology.ru/sci-pop-articles/23-physics/231-pochemu-magnit-prityagivaet-zhelez
Is copper magnetic or not: reasons and methods for determining
Sometimes at home you need to distinguish copper from another metal, and also check the cleanliness of a copper product and whether there are any foreign impurities in it. This can be done based on the appearance of the metal, as well as on determining its properties, in particular, by conducting a test with a magnet.
- general information
- Magnet check
- Alloys
general information
Copper (cuprum) is a metal that has a golden-reddish color and is characterized by high thermal and electrical conductivity. Another distinctive quality of the element is its high ductility. Nuggets are found less and less often in nature; they are most often mined from ore.
Is copper magnetic or not?
When determining the authenticity and purity of a sample, you can turn to an expert, but determining a chemical element in a laboratory is quite expensive. Therefore, you need to focus on several home methods.
First of all, we take a closer look at the color of the product. Since this element tends to oxidize, it is necessary to evaluate the cut or cut of the object. For accuracy, take a sample and compare the color. It should be golden-reddish. Gold has similar colors, as do osmium and cesium.
If copper wire is set on fire, it will not burn, but will first lose its shine and then change color to dark.
You can treat the sample with nitric acid - it should acquire a greenish-blue tint.
Alloys
The most popular alloys using the element are brass (with the addition of zinc) and bronze. As for brass, it does not react to the electromagnetic field in the same way as cuprum. This is due to the fact that copper in this alloy is at least 55% or more. This alloy differs from the pure sample in terms of weight and also in the shape of the chips.
Bronze also has no electromagnetic field. But this alloy is much stronger than cuprum. If you touch samples with your teeth, traces will remain on pure copper, but not on bronze and brass.
If you look at the periodic table, you won’t be able to immediately find out anything about the magnetic properties of elements. To do this, you need to study this material in a little more detail. Modern production produces composite materials that are indistinguishable from copper (the 29th element of the table).
Therefore, testing with an electromagnetic field can be a reliable test for the presence of impurities and the purity of material that will not be attracted to a magnet.
In addition, at home, heating, removing chips, and also carrying out chemical reactions will help identify cuprum, during which care and safety precautions should be observed.
Source: https://DedAntikvar.com/interesnoe/obladaet-li-med-magnitnymi-svojstvami
