In 1911, Kammerlingh onnes while studying the electrical behaviour of metals at low temperatures, he observed that the resistivity of impure metals decreased with temperature and had a finite valve at 0K. But for mercury the resistivity decreased gradually as the temperature is reduced, but abruptly dropped to zero at 4.2K (Figure). Below this temperature,
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Based on permanent magnetic dipoles, materials are further classified into Antiferromagnetic materials Ferrimagnetic materials Antiferromagnetic materials Definition: When the magnitudes of all the antiparallel aligned magnetic dipoles of a material are equal and the resultant magnetisation becomes zero, the material is called antiferromagnetic material. Examples: Manganese oxide (MnO), Chromium oxide (Cr2O3), Ferrous oxide (FeO), etc. This is
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Based on the area of the hysteresis loop, the magnetic materials are classified into soft and hard magnetic materials. Generally the magnetic materials are classified into two types. They are Soft Magnetic materials Hard Magnetic materials Soft Magnetic materials These are materials which are easily magnetized and demagnetised. They are also called as temporary magnets.
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Hysteresis Loop: The word hysteresis literally means lagging behind. “Hysteresis is the phenomenon of lagging of magnetic induction (B) behind the magnetising field (H) of a ferromagnetic material when the specimen is at critical temperature. It is also defined as when a ferromagnetic material is taken through a cycle of magnetisation, the variation of B (magnetic
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Weiss put forward a second hypothesis, namely domain hypothesis. He postulated that the atomic dipole of an atom strongly interacts to the neighbouring atom by a quantum mechanical interaction called exchange interaction. He explain why a sample of ferromagnetic material has spontaneous magnetisation. Explanation The entire ferromagnetic volume splits into a large number of small
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S.No Diamagnetic Material Paramagnetic Material Ferromagnetic Material 1. It is a material in which there is no permanent dipole moment (or) magnetic moment in each atom. The external magnetic field decrease the magnetic induction present in the specimen. It is material in which there is permanent dipole moment in each atom. External magnetic field increases
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Definition : If the interaction among permanent dipoles is strong such that all the dipoles line up in parallel, the material is Ferromagnetic. or The substances which when placed in a magnetic field are strongly magnetised in the direction of applied magnetic field are called ferromagnetic materials. Examples: Nickel (Ni), Cobalt (Co), Iron (Fe), etc.,
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Definition : In certain materials, each atom or molecule possesses a net permanent magnetic moment (due to the orbital and spin magnetic moments) even in the absence of an external magnetic field. or The substances which when placed in a magnetic field are weakly magnetised in the direction of the applied field, are called paramagnetic
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Definition: “Materials which does not have permanent magnetic dipoles” are termed as Diamagnetic materials. or The substances which when placed in a magnetic field become weakly magnetised in a direction opposite to that of the applied magnetising field are called diamagnetic substances. Examples: Gold, Quartz, Water, Copper, Zinc, Germanium, Silver, Lead, Silica, Helium, Bismuth etc.,
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Now, we are going to study the various types of magnetic materials in terms of the magnetic properties of the atomic dipoles and the interactions between them. Very first distinctions is based on whether the atoms carry permanent magnetic dipoles or not. Materials not having permanent magnetic moment Diamagnetic materials Materials which lack permanent dipoles
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