Magnetism and Matter Class 12 Handwritten Notes PDFs Download
1. Introduction:
- The chapter begins by emphasizing the importance of magnetism in our daily lives and various technological applications.
- It introduces the concept of ferromagnetism, paramagnetism, and diamagnetism.
2. Magnetic Dipole Moment and Magnetic Field:
- The magnetic dipole moment of a magnet is the product of its pole strength and the distance between its poles.
- The magnetic field produced by a magnetic dipole at a point depends on the strength of the dipole and the distance from the dipole.
3. Magnetization and Magnetic Intensity:
- Magnetization refers to the process of aligning the magnetic dipoles within a material in the presence of an external magnetic field.
- Magnetic intensity (H) represents the magnetic field produced by the free currents in a material.
4. Magnetic Properties of Materials:
- Diamagnetic materials have a weak negative susceptibility and are slightly repelled by an external magnetic field.
- Paramagnetic materials have a positive susceptibility and are weakly attracted to an external magnetic field.
- Ferromagnetic materials have a large positive susceptibility and exhibit strong attraction and magnetic properties.
5. Permanent Magnets and Electromagnets:
- Permanent magnets are materials that retain their magnetization even after the external magnetic field is removed.
- Electromagnets are temporary magnets created by passing electric current through a coil of wire, producing a magnetic field.
6. Magnetic Domains:
- Ferromagnetic materials consist of tiny regions called magnetic domains, where the atomic dipoles are aligned.
- In the absence of an external magnetic field, the magnetic domains have random orientations, resulting in no net magnetization.
7. Ferromagnetic Substances and Hysteresis:
- Ferromagnetic substances exhibit hysteresis, where the magnetization lags behind changes in the magnetic field.
- The hysteresis loop represents the relationship between the magnetic field and the magnetization during magnetization and demagnetization processes.
8. Curie Temperature and Magnetic Susceptibility:
- The Curie temperature is the temperature at which ferromagnetic and paramagnetic materials lose their permanent magnetic properties.
- The magnetic susceptibility of a material reflects its response to an external magnetic field and can be determined experimentally.
9. Magnetic Materials in Household and Industry:
- Magnetic materials find various applications such as in electric motors, transformers, speakers, magnetic storage devices, and magnetic resonance imaging (MRI).
10. Earth's Magnetism and Magnetic Declination:
- The chapter concludes with a discussion on Earth's magnetic field and its inclination and declination.
- Magnetic declination refers to the angle between the geographic north and the magnetic North Pole at a specific location.
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FAQs about "Magnetism and Matter" in Class 12:
1. What is the difference between diamagnetic, paramagnetic, and ferromagnetic substances?
- Diamagnetic materials have a weak negative susceptibility and are slightly repelled by an external magnetic field.
- Paramagnetic materials have a positive susceptibility and are weakly attracted to an external magnetic field.
- Ferromagnetic materials have a large positive susceptibility and exhibit strong attraction and magnetic properties.
2. How does magnetization occur in a material?
- Magnetization occurs when the magnetic dipoles within a material align themselves in the same direction in the presence of an external magnetic field.
3. What is the difference between permanent magnets and electromagnets?
- Permanent magnets retain their magnetization even after the external magnetic field is removed.
- Electromagnets are temporary magnets created by passing electric current through a coil of wire, producing a magnetic field. Their magnetization depends on the presence of current.
4. What are magnetic domains?
- Magnetic domains are tiny regions in ferromagnetic materials where the atomic dipoles are aligned. In the absence of an external magnetic field, these domains have random orientations, resulting in no net magnetization.
5. What is hysteresis?
- Hysteresis refers to the lagging of magnetization behind changes in the magnetic field in ferromagnetic materials. It is represented by the hysteresis loop and indicates the relationship between the magnetic field and magnetization during magnetization and demagnetization processes.
6. What is the Curie temperature?
- The Curie temperature is the temperature at which ferromagnetic and paramagnetic materials lose their permanent magnetic properties. Above this temperature, the materials become non-magnetic.
7. How is magnetic susceptibility related to material behavior?
- Magnetic susceptibility is a measure of the response of a material to an external magnetic field. It determines whether a substance is diamagnetic, paramagnetic, or ferromagnetic.
8. What are some applications of magnetic materials?
- Magnetic materials find applications in various fields. They are used in electric motors, transformers, speakers, magnetic storage devices (hard drives), and magnetic resonance imaging (MRI) machines.
9. How does Earth's magnetic field work?
- Earth has a magnetic field generated by the movement of molten iron in its core. The north pole of Earth's magnetic field aligns with the geographic south pole and vice versa. This field helps protect the planet from harmful solar radiation.
10. What is magnetic declination?
- Magnetic declination is the angle between the geographic north and the magnetic North Pole at a specific location. It varies depending on the geographical position and changes over time.
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