Diamagnetic, Paramagnetic And Ferromagnetic Materials, Magnetic Field Of The Earth - Diamagnetic, Paramagnetic And Ferromagnetic Materials, Magnetic Field Of The Earth

Slide 2

Topic: Paramagnetic Materials
Definition: Materials that are weakly attracted to an external magnetic field.
Example: Aluminum, Platinum, Oxygen
Characteristics:
- Have some unpaired electrons
- Do not retain magnetism after the external field is removed
- Get magnetized in the direction of the magnetic field
Equation: The magnetic susceptibility of paramagnetic materials is given by: $\chi = \frac{M}{H}$

Slide 3

Topic: Ferromagnetic Materials
Definition: Materials that can be strongly magnetized in an external magnetic field and retain their magnetism after the field is removed.
Example: Iron, Nickel, Cobalt
Characteristics:
- Have a large number of unpaired electrons
- Exhibit spontaneous magnetization
- Exhibit hysteresis
- Can be magnetized and demagnetized easily
Equation: Magnetic field inside ferromagnetic materials is given by: $\mathbf{B=\mu_0(H+M)}$

Slide 4

Topic: Magnetic Field of the Earth
Definition: The magnetic field generated by the Earth due to its core’s magnetism.
Properties:
- Acts similar to a bar magnet
- Axis of the magnetic field is inclined with respect to the Earth’s rotation axis
- Earth’s magnetic poles are not aligned with its geographic poles
Equation: The magnetic field at a point due to the Earth’s magnetic field is given by: $\mathbf{B=\mu_0(H+M)}$

Slide 5

Topic: Diamagnetic Materials (Continued)
Applications:
- Magnetic levitation (Maglev) trains
- Magnetic resonance imaging (MRI) machines
- Magnetic separators
Use of superconducting magnets to achieve levitation and stability
Example: Magnetic levitation of a superconductor

Slide 6

Topic: Paramagnetic Materials (Continued)
Applications:
- Magnetic resonance imaging (MRI)
- Particle accelerators
- Magnetic storage devices
Example: MRI machine and its working principle
Equation: Langevin’s Theory of Paramagnetism: $M = \frac{CNB}{T}$

Slide 7

Topic: Ferromagnetic Materials (Continued)
Applications:
- Transformers
- Motors and generators
- Magnetic hard drives
Example: Electric motor working principle
Hysteresis loop and magnetic memory in ferromagnetic materials

Slide 8

Topic: Magnetic Field of the Earth (Continued)
Earth’s magnetic dipole
Magnetic declination and inclination
Magnetosphere and its role in protecting Earth from the solar wind

Slide 9

Topic: Diamagnetic Materials (Continued)
Diamagnetic substances repel magnetic fields, but the effect is weak
Applications of diamagnetic materials in levitation and materials characterization
Example: Diamagnetic levitation of a frog

Slide 10

Topic: Paramagnetic Materials (Continued)
Paramagnetic materials have a small positive magnetic susceptibility
Applications in magnetic separation, chemical analysis, and magnetic resonance imaging (MRI)
Examples: Magnetic separation of iron ore, MRI scanning process

Slide 11

Topic: Magnetic Field of the Earth (Continued)
Geomagnetic field
- Generated by convection currents in the Earth’s outer core
- Composed of a dipole component and non-dipole components
Magnetic field lines and magnetic flux
Gauss’s law in magnetism: $\mathbf{\oint B \cdot dA = 0}$

Slide 12

Topic: Diamagnetic Materials (Continued)
Magnetic susceptibility of diamagnetic materials: $\chi \approx -1$
Meissner effect and superconductivity
Diamagnetic shielding and levitation applications
Example: Magnetic levitation using a superconductor

Slide 13

Topic: Paramagnetic Materials (Continued)
Magnetic susceptibility of paramagnetic materials: $\chi > 0$
Curie’s law: $M = C \left(\frac{B}{T}\right)$ , where $C$ is a constant
Paramagnetic behavior of atoms and free electrons
Applications of paramagnetic materials in chemical analysis

Slide 14

Topic: Ferromagnetic Materials (Continued)
Magnetic domains and domain walls
Weiss theory and the existence of permanent magnets
Ferromagnetic resonance (FMR) and spin waves
Magnetic anisotropy and magnetic memory

Slide 15

Topic: Magnetic Field of the Earth (Continued)
Magnetic pole reversals and paleomagnetism
Study of past magnetic field through rocks and sediments
Secular variation and geomagnetic jerks
International Geomagnetic Reference Field (IGRF) model

Slide 16

Topic: Diamagnetic Materials (Continued)
Examples: Diamagnetic properties of water, graphite, and copper
Theory of diamagnetism based on Lenz’s law
Measuring diamagnetic susceptibility using Gouy method
Comparison of diamagnetism with other magnetic behaviors

Slide 17

Topic: Paramagnetic Materials (Continued)
Examples: Paramagnetic properties of oxygen, aluminum, and platinum
Effect of temperature on paramagnetism
Brillouin’s law and magnetic susceptibility of paramagnetic ions
Magnetic susceptibility of free electrons in metals

Slide 18

Topic: Ferromagnetic Materials (Continued)
Examples: Ferromagnetic properties of iron, nickel, and cobalt
Saturation magnetization and spontaneous magnetization
Exchange interaction and magnetic ordering
Magnetic domains and their behavior under external magnetic field

Slide 19

Topic: Magnetic Field of the Earth (Continued)
Origin of the Earth’s magnetic field
Dynamo theory and the role of convection currents in the outer core
Geomagnetic storms and auroras
Impact of the Earth’s magnetic field on navigation and communication

Slide 20

Topic: Diamagnetic Materials (Continued)
Industrial applications of diamagnetic materials
Magnetic properties of superconductors at low temperatures
Superconducting levitation and its potential applications
Example: Magnetic levitation of a superconducting train

Slide 21

Diamagnetic, Paramagnetic And Ferromagnetic Materials, Magnetic Field Of The Earth - Diamagnetic, Paramagnetic And Ferromagnetic Materials, Magnetic Field Of The Earth – An introduction

Slide 22

Diamagnetic Materials
- Weak opposing magnetic field
- No unpaired electrons
- No permanent magnetic moment
- Repelled by strong magnetic fields
- Equation: $\mathbf{B=\mu_0(H+M)}$

Slide 23

Paramagnetic Materials
- Weakly attracted to an external magnetic field
- Some unpaired electrons
- No magnetism after field removal
- Get magnetized in the direction of the magnetic field
- Equation: $\chi = \frac{M}{H}$

Slide 24

Ferromagnetic Materials
- Strongly magnetized in an external magnetic field
- Retain magnetism after field removal
- Large number of unpaired electrons
- Exhibit spontaneous magnetization
- Hysteresis and easy magnetization/demagnetization

Slide 25

Magnetic Field of the Earth
- Generated by the Earth’s core
- Acts like a bar magnet
- Magnetic poles not aligned with geographic poles
- Inclined axis with respect to the rotation axis
- Equation: $\mathbf{B=\mu_0(H+M)}$

Slide 26

Diamagnetic Materials (Continued)
- Applications: Maglev trains, MRI machines, magnetic separators
- Superconducting magnets for levitation and stability
- Example: Magnetic levitation of a superconductor

Slide 27

Paramagnetic Materials (Continued)
- Applications: MRI, particle accelerators, magnetic storage devices
- Langevin’s Theory of Paramagnetism: $M = \frac{CNB}{T}$
- Example: MRI machine and working principle

Slide 28

Ferromagnetic Materials (Continued)
- Applications: Transformers, motors/generators, magnetic hard drives
- Electric motor working principle
- Hysteresis loop and magnetic memory
- Example: Hysteresis loop of a ferromagnetic material

Slide 29

Magnetic Field of the Earth (Continued)
- Earth’s magnetic dipole
- Magnetic declination and inclination
- Magnetosphere and solar wind protection
- Example: Magnetic field lines around the Earth

Slide 30

Diamagnetic Materials (Continued)
- Diamagnetic substances repel magnetic fields (weakly)
- Applications in levitation, materials characterization
- Example: Diamagnetic levitation of a frog
- Equation: $\chi \approx -1$ (magnetic susceptibility)