Understanding Magnetism – Class 12 Notes

Summary:

Pole strength is represented as ±m (A-m), with attracting power of a bar magnet zero at the centre, known as the neutral point. Monopoles do not exist, and Gauss’s Law of magnetotail states that ∮𝐵𝐵.𝐴𝐴⃗=0. The force between two poles is given by F = µ₀/4π * 𝑚₁𝑚₂/𝑟², and when freely suspended, a magnet aligns in the N-S direction. Magnetic moment (M) is an axial vector with units of Am², directed from S to N. Bending a bar magnet affects its magnetic moment, and the magnetic field and torque due to a dipole are related. The force between two dipoles is determined by the potential energy (PE), and their shifting involves work done (W). Earth’s magnetism has three components: magnetic declination, magnetic inclination, and horizontal component. Atomic magnetism involves concepts like orbit radii, velocity, time period, frequency, magnetic field, angular momentum, and magnetic moment. Magnetizing field, the intensity of magnetization, magnetic susceptibility, and magnetic permeability are crucial in understanding magnetic materials, while ferromagnetic materials exhibit magnetic hysteresis due to the lagging of B behind H.

Excerpt:

Understanding Magnetism – Class 12 Notes

The information provided discusses various aspects of magnetism, including:

1. Pole strength (±m) in A-m, which is proportional to the area of the cross-section.
2. Attracting power of a bar magnet is zero at the centre, called the neutral point.
3. Monopoles do not exist, and Gauss’ Law of Magnetism states that the integral of the magnetic field over an area is zero.
4. The force between two poles is given by an equation involving magnetic permeability.
5. A freely suspended magnet aligns in the North-South direction, and the product of the pole strength and length of the magnet gives its magnetic moment.
6. Bending a bar magnet results in a new magnetic moment that depends on the angle of bending.
7. Magnetic field and torque due to a dipole are related to the magnetic moment and the angle between the magnetic field and the moment.