Magnetism and Matter

Edited By Team Careers360 | Updated on May 06, 2022 09:14 AM IST

Introduction:
The poles of a bar magnet are comparable to those of an electric dipole's positive and negative charge. One pole is recognized as the north pole, while the other is designated as the south pole. These poles, when hanging freely, point roughly towards the geographical north and south poles. Poles that are similar repel one another, whereas poles that are dissimilar attract each other. A magnet's poles could never be divided. The tangent to a magnetic field line at any place defines the direction of the magnetic ﬁeld at that location. A magnet's magnetic field lines create a close-knit circle. Magnetic field lines outside the core of the magnet go from the north pole to the south pole. There can be no crossing of magnetic field lines. This is because we may draw two tangents at the point of intersection. This would need the presence of two magnetic field directions at the same time, which is not conceivable. The intensity of the magnetic field is proportional to the number of field lines crossing per unit area. If a monopole is held at a given place, its magnetic field is equivalent to the magnetic force received by a unit pole strength. Our earth's magnetism was formerly thought to come from a massive bar magnet located deep within the planet along its rotational axis, but the fundamental argument against this hypothesis is that the interior of the planet is far too hot to sustain any magnetism. The structure of the earth's magnetic field changes with time and place. The solar wind has the greatest impact on this.

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List of topics according to NCERT and JEE Main/NEET syllabus:

Bar Magnet
Magnetic Field Lines
Torque on a Magnetic Dipole in Uniform Magnetic Field
Work done in Rotating a Magnetic Dipole in Uniform Magnetic Field
Earth’s Magnetism
Magnetic Inclination or Dip
Magnetisation
Magnetic Susceptibility
Magnetic Properties of Materials
Diamagnetism
Ferromagnetism
Paramagnetism
Curie’s Law
Curie-Weiss law

Related Topics,

Important concepts and Laws:

The magnetic axis is the line connecting the two poles of a magnet, and the magnetic meridian is the vertical plane running through the axis of a freely suspended or pivoted magnet. The notion of lines of force was first suggested by Michael Faraday. A line of force, according to him, is an imaginary curve whose tangent at a location determines the direction of the field at that place. Magnetic force lines are closed curves. Lines of force outside a magnet go from north to south pole, whereas within they run from south to north.No lines flow through the space within a soft iron ring when it is put in a magnetic field. "Magnetic screening" or "Shielding" is the term for this occurrence.

The Law of Curie - The susceptibility of a paramagnetic material to magnetic fields is inversely related to the absolute temperature T.

The law of Curie-Weiss - A ferromagnetic substance becomes an ordinary paramagnetic substance at temperatures above the Curie temperature, and its magnetic susceptibility obeys the Curie-Weiss equation. Diamagnetic materials become weakly magnetised in the opposite direction of the magnetising field. In the direction of the magnetising field, paramagnetic substances become weakly magnetised. Ferromagnetic Substances: When put in a magnetising field, these substances become highly magnetised in the direction of the field. The magnetic field lines of the earth resemble a magnetic dipole at the planet's centre. The north magnetic pole is located near the geographic north pole, whereas the south magnetic pole is located near the geographic south pole

NCERT Notes Subject wise link:

Importance of magnetism and matter class 12

A significant chapter in Physics deals with magnetism and matter. When the matter is subjected to magnetism, it responds in a certain way. The production of a variety of magnetic materials is triggered by the presence of a magnetic field. Magnetism And Matter Class 12 goes into much detail on every topic related to magnets. The chapter on magnetism and matter is crucial for CBSE students' exams. The fundamental principles covered in this chapter serve as a foundation for more advanced subjects. It is critical that these notions are understood from the start. Not only for the CBSE students class 12 physics ch 5 magnetism and matter is important but it also has a heavy weightage in NEET and JEE. it becomes an important chapter because it has a lot of theory about which direct questions are asked so it becomes an easy score topic

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Frequently Asked Questions (FAQs)

1. Which is the most paramagnetic substance as discussed in class 12 physics ch 5 magnetism and matter?

The most paramagnetic substance is manganese (Mn).

2. How can we use the topic of magnetism and matter in real life?

Refrigerator and freezer doors are sealed with magnets to provide a secure seal. They provide electricity to stereo speakers, earphones, and TVs. Magnets are used to store data in computers and are crucial in scanning devices known as MRIs (magnetic resonance imagers), which doctors use to examine people's inside organs.

3. What is the difference between hard and soft magnets as covered in class 12 physics ch 5 magnetism and matter?

Hard magnetic materials or hard ferromagnets are ferromagnetic materials that hold their magnetism for an extended length of time. Alnico (an alloy of iron, aluminium, nickel, cobalt, and copper) and naturally occurring lodestone are two hard magnetic minerals. Material for permanent magnets should have a high retentivity and coercivity. Soft magnetic materials or soft ferromagnets are ferromagnetic materials that keep their magnetism as long as the external field exists. Soft ferromagnets are made out of soft iron. Electromagnets are made from this type of material.

4. In neet, what is the weightage of magnetic and matter?

Magnetism accounts for around 2% of the total number of questions presented in the previous eight years, according to the NEET Chapter Wise Weightage for the NEET medical entrance test.

5. What are the properties of Paramagnetism?

The magnetic field inside the paramagnetism material (B) is larger than the magnetic field in empty space
Paramagnetism material has a relative permeability larger than one.
Paramagnetic substances have a low and positive magnetic susceptibility.

6. What role do magnetism and matter have in the JEE main?

Around two questions regarding magnetism are asked in the jee main test, accounting for around 6.6 per cent of the whole exam.