File Name: classification of magnetic materials and their properties .zip
The two most common types of magnetism are diamagnetism and paramagnetism, which account for the magnetic properties of most of the. Classification of Magnetic Materials They are diamagnetic, paramagnetic and ferromagnetic materials which are dealt with in this section.
- Types of Magnetic Materials With Examples
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- Types of Magnetic Materials
Aluminum, manganese, etc are examples of paramagnetic materials, Copper, water, alcohol are some examples of diamagnetic materials. Iron, Nickle, and cobalt are some examples of Ferromagnetic materials. See also: Hysteresis loop.
Types of Magnetic Materials With Examples
Its power of attracting iron was known for centuries before Christ. Magnetic ores were found in Magnesia, the name of a region of the ancient Middle East, in what is now Turkey and the word 'magnet' owes its origin to this fact. Magnetism, The phenomenon by which materials assert an attractive or repulsive force or influence on other materials. However, the underlying principles and mechanisms that explain the magnetic phenomenon are complex and subtle, and their understanding has eluded scientists until relatively recent times.
Magnetism is a force that arises due to the motion of electric charges. All materials without exception are magnetic some are strongly magnetic and some are very weakly magnetic. By, magnetic, it is meant, the ability of a material to respond to an external magnetic field, or in other words, the degree to which a material can be magnetized. All materials can be magnetized, with varying degrees of magnetization. Nowadays, magnetic materials have greatly influenced our daily lives.
Many of our modern technological devices rely on magnetism and magnetic materials; these include electric motors, electrical power generators and transformers. Magnetic materials have found wide use for storing information as magnetic recording tapes, computer disks and credit cards. In this chapter we will discuss the origin of magnetism in materials in terms of the magnetic dipole moments of the individual atoms.
A complete understanding of magnetic properties requires a sound knowledge of quantum mechanics which is beyond this material, but a qualitative understanding can be achieved. The phenomena of diamagnetism, paramagnetism, ferromagnetism, anti-ferromagnetism and ferrimagnetism Ferrites and some of the different magnetic materials are discussed.
H describes field outside the material. Magnetic field intensity at any point in a magnetic field is the force experienced by a unit North Pole placed at a given point in a magnetic field. If the magnetic field is generated by means of a cylindrical coil or solenoid consisting of N closely spaced turns, having a length l, and carrying a current of Magnetic induction or Magnetic flux density B :Magnetic induction or magnetic flux density in any material is the number of magnetic lines of force passing normally through unit area.
B represents the magnitude of the internal field strength within a substance that is subjected to an H field. It is the ease with which the material allows magnetic lines of force to pass through it or the degree to which magnetic field can penetrate a given medium is called its permeability. Mathematically permeability is equal to the ratio of the magnetic induction B inside the material to the applied magnetic intensity H. The Intensity of magnetization M or I is defined as the magnetic moment per unit volume in a material.
It is totally depends on the nature of material. Magnetization of a material is proportional to the magnetic field intensity applied i.
It the ease with which a magnetic material can be magnetised by the magnetising force. The magnetic susceptibility of a material is the ratio of intensity of magnetisation M inside the material to the magnetising field H. The fundamental reason for the response of a material to an external magnetic field is that the atoms possess magnetic moments.
That is, atom acts like a tiny magnet. The magnetic properties of solids originate due to the motion of electrons. There are two types of electron motions: orbital and spin motion.
There are three sources that contribute to atomic magnetic moment: a Orbital magnetic moment: Magnetic moment due to the moment of electrons in orbits around the nucleus, i.
The contribution due to spin angular moment of the nucleus i. Orbital Magnetic MomentIn an atom electrons revolve round the nucleus in different orbits these revolving electrons constitute an electric current in the orbits this is equivalent to current in a closed circuit fig. Suppose an electron is revolving around a nucleus.
Let the charge on the electron be 'e' and the radius of its orbit be 'r'. The revolving electron is like a loop of current. The direction of current in this loop is opposite to the direction of the revolution of the electron. Thus, if the electron revolves in the clockwise direction, it constitutes an anticlockwise current, and vice versa. The orbital magnetic moment is given by the equation Minutes Properties of different classes of magnetic materials:Now we are going to study the various properties of magnetic materials in terms of the magnetic properties of the atomic dipoles and the interaction between them.
The first distinction is based on whether the atoms carry permanent magnetic dipoles or not. Materials Thus diamagnetism is the phenomenon by which the induced magnetic moment is always in the opposite direction of the applied field.
Thus, the relative permeability is less than unity however, only very slightly , and the magnetic susceptibility is negative; that is, the magnitude of the B field within a diamagnetic solid is less than that in a vacuum. The volume susceptibility for diamagnetic solid materials is on the order of When placed between the poles of a strong electromagnet, diamagnetic materials are attracted toward regions where the field is weak.
Though diamagnetism is present in all materials but it is masked by other types of magnetism because it is very weak. It can be observed only when other types of magnetism are absent.
Properties of Diamagnetic Materials1. An atom of this material does not contain permanent dipoles. An atom of this material has no magnetic dipole moment. The effect is weak and often masked by other kinds of magnetism. A Dia-magnet is weakly repelled by a normal magnet.
Relative permeability is less than 1 but only slightly less than unity. Magnetic susceptibility is negative but only slightly less than unity. Magnetic susceptibility is independent of temperature. Magnetic susceptibility is independent of applied magnetic field strength.
Atomic orbitals are completely filled no electron is un-paired. In the absence of external magnetic field the dipoles are randomly oriented resulting in zero net magnetic moment. When external magnetic field is applied, some of the permanent dipoles try to align in the direction of the magnetic field fig. Since few dipoles try to align in the direction of the magnetic field the net magnetic moment produced in the material is small so the material is feebly magnetised.
When placed inside the magnetic field the material allows magnetic lines of force to pass through it as shown in fig. There is no interaction between the adjacent dipoles they are acted upon individually. The relative permeability is greater than unity. Magnetic susceptibility is positive but relatively small value.
The susceptibilities of paramagnetic values range from 10 -5 to 10 2. These materials are used in lasers and masers. Where one can create the required energy levels of transition. Paramagnetic property of oxygen is used in the NMR imaging instrument which is used to diagnose the brain tumor or blood clot in the brain. Properties of paramagnetic materials1.
They attract magnetic lines of force when placed in magnetic field. In the absence of external magnetic field the dipoles are randomly oriented. An atom of this material possesses a non-zero magnetic dipole moment.
Possess permanent dipole moment. Relative permeability is slightly greater than unity. Magnetic susceptibility is positive and small. Magnetic susceptibility is independent of applied magnetic field strength but depend on temperature. With increase in temperature the susceptibility of the material decreases. The susceptibility of a ferromagnetic material is temperature dependent. A ferromagnetic material exhibits two different properties.
Below a particular temperature called Curie temperature it behaves as a ferromagnetic and above that Curie temperature it behaves as a paramagnetic material fig. The relative permeability is very large. Magnetic susceptibility is as high as 10 6. Curie Temperature:Even though electronic exchange forces in ferromagnets are very large, thermal energy eventually overcomes the exchange and produces a randomizing effect. This occurs at a particular temperature called the Curie temperature T C.
Below the Curie temperature, the ferromagnet is ordered and above it, disordered. The saturation magnetization goes to zero at the Curie temperature. A typical plot of magnetization versus temperature for magnetite is shown fig. Antiferromagnetism depends on temperature.
The adjacent dipoles are aligned in antiparallel direction. These are also ceramic and ionic in nature. They exhibit permanent magnetization.
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The magnetic materials are broadly classified into three categories depending on their attraction towards a magnet. When a material is placed within a magnetic field, the magnetic forces of the material's electrons will be affected. This effect is known as Faraday's Law of Magnetic Induction. However, materials can react quite differently to the presence of an external magnetic field. Rods are available in 33 material. Magnetic Field: The magnetic field is an imaginary line of force around a magnet which enables other ferromagnetic materials to get repelled or attracted towards it. The magnetic field lines are formed due to various reasons like orbital movement of electrons, current flowing in a conductor etc.
Ferromagnetism is the basic mechanism by which certain materials such as iron form permanent magnets , or are attracted to magnets. In physics , several different types of magnetism are distinguished. Ferromagnetism along with the similar effect ferrimagnetism is the strongest type and is responsible for the common phenomenon of magnetism in magnets encountered in everyday life. An everyday example of ferromagnetism is a refrigerator magnet used to hold notes on a refrigerator door. The attraction between a magnet and ferromagnetic material is "the quality of magnetism first apparent to the ancient world, and to us today". Permanent magnets materials that can be magnetized by an external magnetic field and remain magnetized after the external field is removed are either ferromagnetic or ferrimagnetic, as are the materials that are noticeably attracted to them. Only a few substances are ferromagnetic.
Magnetic susceptibility , quantitative measure of the extent to which a material may be magnetized in relation to a given applied magnetic field. This ratio, strictly speaking, is the volume susceptibility, because magnetization essentially involves a certain measure of magnetism dipole moment per unit volume. Magnetic materials may be classified as diamagnetic, paramagnetic, or ferromagnetic on the basis of their susceptibilities.
Magnetic Materials and their Applications discusses the principles and concepts behind magnetic materials and explains their applications in the fields of physics and engineering. The book covers topics such as the principal concepts and definitions related to magnetism; types of magnetic materials and their electrical and mechanical properties; and the different factors influencing magnetic behavior. The book also covers topics such as permanent-magnet materials; magnetic materials in heavy-current engineering; and the different uses of magnetic materials.
Types of Magnetic Materials
The magnetic materials are generally classified into three types based on the behaviour of materials in a magnetising field. They are diamagnetic, paramagnetic and ferromagnetic materials which are dealt with in this section. The orbital motion of electrons around the nucleus produces a magnetic field perpendicular to the plane of the orbit. Thus each electron orbit has finite orbital magnetic dipole moment. Since the orbital planes are oriented in random manner, the vector sum of magnetic moments is zero and there is no resultant magnetic moment for each atom. In the presence of an external magnetic field, some electrons are speeded up and some are slowed down. The induced moment disappears as soon as the external field is removed.
All types of materials and substances posses some kind of magnetic properties which are listed further down in this article. For example: aluminium, tin magnesium etc. Their relative permeability is small but positive. For example: the permeability of aluminium is: 1. Such materials are magnetized only when placed on a super strong magnetic field and act in the direction of the magnetic field. The resultant magnetic force is therefore zero.
К несчастью для того, кто это придумал, коммандер Стратмор не нашел в этой выходке ничего забавного. Два часа спустя был издан ставший знаковым приказ: СОТРУДНИК КАРЛ ОСТИН УВОЛЕН ЗА НЕДОСТОЙНЫЙ ПОСТУПОК С этого дня никто больше не доставлял ей неприятностей; всем стало ясно, что Сьюзан Флетчер - любимица коммандера Стратмора. Но не только молодые криптографы научились уважать Стратмора; еще в начале своей карьеры он был замечен начальством как человек, разработавший целый ряд неортодоксальных и в высшей степени успешных разведывательных операций.
Он надеялся, что не совершает ошибку. - Сьюзан, - начал он, - этого не должно было случиться. - Он провел рукой по своим коротко стриженным волосам.