Diamagnetic, Paramagnetic And Ferromagnetic Materials:

• Magnetic materials classification: Diamagnetic materials: Substances that are weakly repelled by magnetic fields. Examples include copper, silver, and gold. Paramagnetic materials: Substances that are weakly attracted to magnetic fields. Examples include aluminum, magnesium, and oxygen. Ferromagnetic materials: Substances that are strongly attracted to magnetic fields and can retain their magnetism even after the magnetic field is removed. Examples include iron, nickel, and cobalt.

• Diamagnetism - explanation and examples:

• Diamagnetism occurs due to the cancellation of magnetic moments of paired electrons. All paired electrons in a diamagnetic material have their spins paired in opposite directions, resulting in a net magnetic moment of zero.
• They weakly oppose an external magnetic field.

• Paramagnetism - explanation and examples:

• Paramagnetism occurs due to the presence of unpaired electrons in a material. Unpaired electrons have a net magnetic moment, and when these moments are aligned, they result in a net magnetic field.
• The paramagnetic behavior is temperature dependent and inversely proportional, as temperature increases, the degree of paramagnetism decreases.

• Ferromagnetism - explanation, Curie temperature, and examples:

• Ferromagnetism is the most substantial form of magnetism. It occurs in materials where the unpaired electrons neighboring atoms align in the same direction, creating strong magnetic domains.
• They can retain their magnetism even after the magnetic field is eliminated because the magnetic domains remain aligned.
• Curie temperature: The temperature at which a ferromagnetic material loses its ferromagnetism and becomes paramagnetic.

Magnetic Field Of The Earth:

• Geomagnetic field overview and its importance:

• The space around Earth where its magnetic influence can be detected is known as the geomagnetic field.
• It is vital for life on Earth, protecting the planet from harmful solar radiation and enabling animal navigations.

• Earth’s magnetic poles and shifting:

• Earth’s magnetic field closely resembles a dipole (a magnet with two poles) with a north-seeking pole and a south-seeking pole.
• These poles are not fixed and can shift over time. The magnetic north pole has been drifting steadily toward Siberia.

• Magnetic declination and inclination:

  • Magnetic declination: The angle between true north and the direction indicated by a compass needle. It varies depending on the location.
  • Magnetic inclination or dip angle: The angle between the Earth’s magnetic field lines and the horizontal plane.

• Magnetic storms and their effects:

• Intense geomagnetic storms can disrupt power grids, communication systems, and damage satellites.
• They occur due to solar flares and coronal mass ejections from the sun.

• Earth’s magnetic field generation - Dynamo theory:

• The dynamo theory explains the generation and maintenance of Earth’s magnetic field.
• It suggests that the Earth’s rotation and convection currents within the conductive liquid outer core create a self-sustaining dynamo effect, generating the magnetic field.

• Applications of Earth’s magnetic field (compasses, navigation, etc.):

• Used in compasses, navigation, measuring magnetic properties, and as a geologic survey.
• Palemagnetism provides insights into Earth’s history, tectonic movements, and reconstructions.
• The magnetic field also guides migratory animals’ movements.

References:

• NCERT class 11 Physics, Chapter 6: Magnetic Effects of Current and Magnetism.
• NCERT class 12 Physics, Chapter 5: Magnetism and Matter.