Chapter 5 – Magnetism and Matter

The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:

Introduction

The motion of electrons in atoms gives rise to the concept of magnetism. Magnetism assists in understanding the behavioral property of matter. Various types of magnetic materials such as paramagnetic or diamagnetic rise, when a matter is placed in a magnetic field.  Magnetism and Matter are very closely related to each other. Matter can be explained, as a substance that has mass and occupies space. A Matter can be categorized, like solid, liquid, and gas. The relation of magnetism with Matter is that magnetism studies the behavior of matter when placed on a magnetic field.

What happens to the dipole moment of a magnet?

When a magnet is placed in a uniform magnetic field (B), a dipole moment (m) is experienced by a magnet (m). It experiences :-

• There will be zero-force
• m*B will be a twisting force
• -m*B will be potential energy. The calculation of zero energy can be done when m is vertical to B.

Magnetic Field Lines

The imaginary lines in a magnetic field are called Magnetic Field Lines. The region around a magnetic material or which shows moving electric charge within which magnetism force acts. The alternative way used to represent the information contained within a magnetic vector field is called Magnetic Field Lines.

The Properties of Magnetic Field Lines are:-

• Magnetic field lines never cross each other.
• The density sees the strength of the fields of the field lines.
• The magnetic field always makes Closed-loops.
• Magnetic Field always starts from the north pole and ends at the south pole.

Earth’s Magnetism

The Earth’s Magnetic field extends millions of kilometers into outer space. Although its extension is broad, and far in terms of field strength, It is very weak. The dynamo effect theory explains how Earth’s Magnetism is caused. Earth’s Magnetism is mainly happening due to the convection currents of molten iron and nickel in the earth’s core.

Components of Earth’s Magnetic Field

• Magnetic Declination
• Magnetic Inclination
• The horizontal component, of the earth’s magnetic field

The Magnetization and Magnetic Intensity

Abounds with the baffling, variety of elements and compounds the earth beside, have been combining new alloys, compounds, and even elements. As you know, the circulation electron in an atom has a magnetic moment and these moments add up vectorially, and they can give a net magnetic moment which is non-zero.

Hysteresis Curve

A system that involves a magnetic field, the hysteresis occurs there. Ferromagnetic substances properties entail hysteresis.

The explanation of Hysteresis Curve is, given below:-

• When you place an unmagnetized material inside the solenoid and increase the current through the solenoid, that will increase the magnetic intensity (H), as shown in X-axis.
• When H increases, the magnetic field B increases as well and reaches saturation (0a)
• When you reach saturation, then there is no need of increasing the current, therefore decreasing the current, and as a result in H magnetic intensity will also decrease.
• When at a point H is equal to zero, B, as shown in Y-axis, is not equal to zero (ab)
• Then the value of H at B=0 is called retentivity, and if you reverse the current and slowly increase it as shown by (bc). Then the value of H at c(B=0) is called coercivity.

Note – The Curve may vary from different materials like soft iron, steel, etc.

Relative Magnetic Permeability

The magnetic lines of force are permitted to pass through a material. The representation is through  μR = (B/Bo) = (μ/μo

Bo – Magnetic lines number per unit in a vacuum

B – Number of magnetic lines of force per unit area in the given material

μ – Magnetic permeability of a material

μo – Magnetic permeability of free space

μR – Value for vacuum is one.

Magnetic permeability materials are:-

• Diamagnetism

Diamagnetic substances are those on the external magnetic field that tends to move from stronger to the weaker part. The Resultant magnetic moment of an atom is zero in diamagnetic substances.

• Paramagnetism

Paramagnetism substances get weakly magnetised when they are placed in an external magnetic field. They tend to move from a weak magnetic field to a strong magnetic field.

• Ferromagnetism

Ferromagnetic substances get strongly magnetised when they are placed in an external magnetic field. In a paramagnetic material, the individual atoms in a ferromagnetic material possess a dipole moment.

Magnetic Intensity

Magnetic Intensity means the degree at which a magnetic field magnetises a material. The Magnetic Intensity is several ampere-turns flowing round a unit length of a toroidal solenoid to produce that magnetic field in the solenoid. It can be shown by

H = n * current.

N – Number turns per unit length of a toroidal solenoid carrying current i. Vector quantity and its SI unit is Am‒1

Intensity Of Magnetisation

It simply means a magnetic moment per unit volume of the material. The formula is:-

I = Magnetic moment/ Volume = M/V

Magnetic Susceptibility

Magnetic Susceptibility is the ratio of the intensity of magnetisation (M) induced in the material to the magnetising force (H) applied to it. The formula for Magnetic Susceptibility:-

Formula – X = Magnetic Susceptibility/Field intensity

X – Magnetic Susceptibility

M – Magnetization

H – Field intensity

Curie’s Law in Magnetism

As per this law, the intensity of Magnetization (I) of magnetic material is directly proportional to the magnetic field H and inversely proportional to the absolute temperature T of the material.

Formula – M = Curie constant x (Magnetic field/Absolute temperature)

M – Magnetism

B – Magnetic field

T – Absolute temperature

C – Curie constant

The Curie’s law in Magnetism is not that strong magnetic fields, but hold good for high temperature.

Magnetism and Matter is a phenomenon that has a significant role in almost every field of science. This chapter is very crucial, especially for your CBSE class 12 exams. Learn more about magnetism and matter with conceptual videos on the MSVgo app.

High School Physics

• Alternating Current
• Atoms
• Communication Systems
• Current Electricity
• Dual nature of Radiation and Matter
• Electric Charges and Fields
• Electricity
• Electromagnetic Induction
• Electromagnetic Waves
• Electrons and Photons
• Electrostatic Potential and Capacitance
• Fluid Pressure
• Force and Acceleration
• Force And Laws Of Motion
• Gravitation
• Internal Energy
• Kinetic Theory
• Law of motion
• Light – Reflection And Refraction
• Magnetic Effects Of Electric Current
• Magnetism and Matter
• Management Of Natural Resources
• Mechanical properties of Fluids
• Mechanical properties of Solids
• Motion
• Motion in a plane
• Motion in a straight line
• Moving Charges and Magnetism
• Nuclear Energy
• Nuclei
• Oscillations
• Our Environment
• Paths of Heat
• Physical world
• Ray optics and optical instruments
• Semiconductor Devices
• Semiconductor Electronics: Materials, Devices and Simple Circuits
• Simple Machines
• Sound
• Sources Of Energy
• Specific and Latent Heats
• Spherical Mirrors
• Static Electricity
• Systems of Particles and Rotational motion
• Thermal properties of matter
• Thermodynamics
• Units and Measurement
• Vectors, Scalar Quantities and Elementary Calculus
• Wave Optics
• Waves
• Work, Power and Energy

High School Chemistry

• Acids, Bases and Salts
• Alcohols, Phenols and Ethers
• Aldehydes, Ketones and Carboxylic Acids
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• Alkyl and Aryl Halides
• Amines
• Analytical Chemistry
• Atomic Structure
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• Basic concepts of Chemistry
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• Chemical Bonding and Molecular Structures
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• Chemistry in Everyday Life
• Chemistry of p-Block elements
• Chemistry of Transition and Inner Transition
• Classification of Elements
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• Cyanide, Isocyanide, Nitro compounds and Amines
• Electrochemistry
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• Matter
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• States of Matter
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• Study of Compounds
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• Surface Chemistry
• The d-block and f-block elements
• The Gaseous State
• The p-Block Elements
• The Periodic Table
• The s-Block Elements
• The Solid State
• Thermodynamics

High School Biology

• Absorption and Movement of Water in Plants
• Anatomy of Flowering Plants
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• Locomotion and Movement
• Microbes in Human Welfare
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• Molecular Basis of Inheritance
• Morphology of Flowering Plants
• Neural Control And Coordination
• Nutrition in Human Beings
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• Photosynthesis
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• Plant Growth and Development
• Plant Kingdom
• Pollination and Fertilization
• Pollution; Sources and its effects
• Principles of Inheritance and Variation
• Reproduction and Development in Angiosperms
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• The Endocrine System
• The Fundamental Unit Of Life
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• Tissues
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• Transport in Plants

High School Math

• Algebra – Arithmatic Progressions
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• Permutations and Combinations
• Probability
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• Trignometry – Height and Distance
• Trignometry – Identities
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Middle School Science

• Acids, Bases And Salts
• Air and Its Constituents
• Basic Biology
• Body Movements
• Carbon and Its Compounds
• Cell – Structure And Functions
• Changes Around Us
• Chemical Effects Of Electric Current
• Coal And Petroleum
• Combustion And Flame
• Components Of Food
• Conservation Of Plants And Animals
• Crop Production And Management
• Electric Current And Its Effects
• Electricity And Circuits
• Elements and Compounds
• Fibre To Fabric
• Food production and management
• Force And Pressure
• Forests: Our Lifeline
• Friction
• Fun With Magnets
• Garbage In, Garbage Out
• Getting To Know Plants
• Health and Hygiene
• Heat
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• Life Processes: Nutrition in Animals and Plants
• Materials: Metals And Non-Metals
• Matter and Its States
• Metals and Non-metals
• Micro Organisms: Friend And Foe
• Motion And Measurement Of Distances
• Motion And Time
• Nutrition In Animals
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• Organization in Living Things
• Our Environment
• Physical And Chemical Changes
• Pollution and conservation
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• Reaching The Age Of Adolescence
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• Respiration In Organisms
• Rocks and Minerals
• Separation Of Substances
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• Some Natural Phenomena
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• The Living Organisms And Their Surroundings
• Transfer of Heat
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• Transportation In Animals And Plants
• Universe
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• Water: A Precious Resource
• Weather, Climate And Adaptations Of Animals To Climate
• Winds, Storms And Cyclones

Middle School Math

• Area and Its Boundary
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• Similarity
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• Subtraction
• Tables And Shares
• Tenths and Hundredths
• Time