Magnetism and Matter

Introduction

• Try to understand all the formulas and concepts of the chapter Magnetism and Matter.
• Concepts that will be covered:
  • Bar Magnet
  • Magnetic Field and its elements
  • Poles and Pole Strength

Bar Magnet

• Concept of Poles:
  • An imaginary concept that generates a magnetic field.
  • Pole strength measures the capacity of the magnetic field by the pole.
  • North Pole can be understood as positive charge and South Pole as negative charge.

Magnetic Field

• Magnetic Field due to a Bar Magnet:
  • Formula: μ₀/4π × (2Md)/(d² - l²/4)²
  • Calculation of magnetic field based on pole strength and distance.
• Dipole Moment:
  • Dipole Moment = M × D (Pole Strength × Distance)

Magnetic Field Lines

• Direction of Field Lines:
  • They go out of the North Pole and enter towards the South Pole.
  • Form a closed loop.

Terrestrial Magnetism

• Earth's Magnetism:
  • The magnetic field of the Earth is generated due to molten metal.
  • An angle of 11.5 degrees exists between geomagnetic North and South Pole.
• Elements of the Magnetic Field:
  • Declination, Inclination, and Horizontal Component.

Magnetic Intensity and Susceptibility

• Magnetic Intensity (H):
  • Measured by B₀/μ₀ or B/μ.
• Magnetic Susceptibility:
  • I = χH
  • Applied for para and diamagnetic materials.

Torque and Potential Energy

• Torque:
  • Measured as M × B.
• Potential Energy:
  • U = -M · B

Hysteresis

• Hysteresis Loop:
  • Graphic representation of magnetization in ferromagnetic material.
  • Measurement of retentivity and coercivity.

Magnetic Materials

• Para, Ferro, and Diamagnetic Materials:
  • Para: Slightly attracted, μr > 1
  • Ferro: Strongly attracted
  • Dia: Slightly resistive, μr < 1

Curie Law

• Curie's Law:
  • χ ∝ 1/T
  • Susceptibility decreases with an increase in temperature.

Conclusion

• Review all concepts and formulas.
• Continue study through mind maps.