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Questions and Answers
Which material is considered ferromagnetic due to its high permeability?
Which material is considered ferromagnetic due to its high permeability?
What characterizes paramagnetic materials?
What characterizes paramagnetic materials?
Which type of magnet is used in transformer cores due to its design?
Which type of magnet is used in transformer cores due to its design?
Diamagnetic materials are defined by what property?
Diamagnetic materials are defined by what property?
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Which of the following is a natural magnet?
Which of the following is a natural magnet?
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What is the primary feature of artificial magnets compared to natural magnets?
What is the primary feature of artificial magnets compared to natural magnets?
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Magnetic flux penetration is measured by which property?
Magnetic flux penetration is measured by which property?
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Which of the following correctly describes nonmagnetic materials?
Which of the following correctly describes nonmagnetic materials?
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What happens to a magnet when it is broken?
What happens to a magnet when it is broken?
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What is the principle behind magnetic repulsion?
What is the principle behind magnetic repulsion?
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What signifies the directive property of a magnet?
What signifies the directive property of a magnet?
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What is the relationship between magnetic induction field B and magnetic field H?
What is the relationship between magnetic induction field B and magnetic field H?
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Which of the following materials is not considered ferromagnetic?
Which of the following materials is not considered ferromagnetic?
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What is the value of the magnetic induction field B expressed in?
What is the value of the magnetic induction field B expressed in?
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Which statement about magnetization is false?
Which statement about magnetization is false?
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What does the magnetic permeability (μ) signify in the formula B = μ0.μr.H?
What does the magnetic permeability (μ) signify in the formula B = μ0.μr.H?
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What defines the retentivity of a magnet?
What defines the retentivity of a magnet?
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Which type of magnet quickly loses its magnetism when the external magnetizing force is removed?
Which type of magnet quickly loses its magnetism when the external magnetizing force is removed?
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Which of the following materials is classified as a permanent magnet?
Which of the following materials is classified as a permanent magnet?
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What is a characteristic of flat magnets used in generators and motors?
What is a characteristic of flat magnets used in generators and motors?
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What happens to steel when it is placed in a magnetic field created by a solenoid?
What happens to steel when it is placed in a magnetic field created by a solenoid?
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Which alloy is considered one of the very best for making magnets?
Which alloy is considered one of the very best for making magnets?
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What is the small amount of magnetism remaining in a soft iron magnet called?
What is the small amount of magnetism remaining in a soft iron magnet called?
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Which type of magnets is formed as a curved bar in a horseshoe shape?
Which type of magnets is formed as a curved bar in a horseshoe shape?
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Study Notes
Types of Magnets
- Magnets are either natural or artificial.
- Artificial magnets are divided into permanent magnets, which retain their magnetism after removing the magnetizing force, and temporary magnets, which lose their magnetism quickly after the magnetizing force is removed.
- Modern permanent magnets are made from special alloys (e.g., Alnicos, Ferrites, Neo magnets, and Samarium-Cobalt) which are created through research and development.
- Alnico is considered one of the best permanent magnets because it is an alloy of iron, aluminum, nickel, and cobalt.
- Other alloys with high magnetic properties include Remalloy™ and Permendur™.
- The retentivity of a magnet is determined by the type of metal and indicates how well it retains its magnetism.
- Soft iron is easily magnetized but loses most of its magnetism quickly. The remaining magnetism is called residual magnetism, and it is essential for electrical applications, such as generator operation.
- Steel is magnetized in a magnetic field created by a solenoid and retains its magnetism after the field is removed.
Horseshoe Magnets
- Horseshoe magnets are commonly manufactured in two forms: a long bar curved into a horseshoe shape, and two bars connected by a third bar (yoke).
Magnetic Material
- Materials like soft iron and ferrous metals have high permeability, indicating the ease with which magnetic flux can penetrate a material.
- Permeability is measured on a scale based on a perfect vacuum with a rating of one.
- Air and nonmagnetic materials have a permeability rating close to one.
- Paramagnetic materials, such as nickel and cobalt, have a permeability greater than one.
- Ferromagnetic materials, like iron and its alloys, have the highest permeability.
- Diamagnetic materials, such as bismuth, have a permeability less than one.
Types of Magnets
- Magnets come in various shapes, such as balls, cylinders, or disks.
- Ring magnets, or Gramme rings, are closed loop magnets often used in instruments and have no poles.
Magnetic Quantities
- Magnetic field "H" refers to the area around a magnet or coil where its influence is felt. The field lines move from the north pole to the south pole outside the magnetized material. It is expressed in A/m.
- Magnetic Induction field "B" refers to the value of a magnetic field at a specific point in space. Its value depends on the shape and material of the magnet.
- B = 𝜇0.𝜇𝑟.𝐻 (where B is in Tesla T, 𝜇0 is vacuum permeability, and 𝜇𝑟 is relative permeability).
Properties of a Magnet
- They attract ferromagnetic materials like iron, cobalt, and nickel.
- Like magnetic poles repel, while unlike poles attract.
- Lines of force from like poles do not cross, and they turn aside as the poles are brought together, causing mutual repulsion.
- A freely suspended magnet always aligns in a north-south direction.
- A magnetic pole cannot be isolated.
- Magnetization can be permanent or temporary.
- Breaking a magnet creates two new magnets, each with a south pole and a north pole.
- Between two poles of a horseshoe magnet, a uniform field exists.
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Description
Explore the different types of magnets, including natural and artificial variations. Dive into the specifics of permanent and temporary magnets, their compositions, and their applications in technology. Test your understanding of materials like Alnico and their properties related to magnetism.
