Magnetism and Matter
Magnetic Properties of Materials
Ferromagnetic Materials: exhibit strong magnetic properties and can be easily magnetized. Examples include iron, cobalt, and nickel
Paramagnetic Materials: Display weak magnetic properties and are weakly attracted to a magnetic field. Examples include aluminum and platinum.
Diamagnetic Materials: exhibit very weak repulsion when placed in a magnetic field. Examples include copper and bismuth.
Magnetic Field Intensity (H)
Magnetic field intensity (H) is a measure of the strength of a magnetic field in a material.
It is related to the magnetization (M) of the material by the equation H=B/μ0−M, where B is the magnetic flux density and μ0 is the permeability of free space.
Magnetic Susceptibility ( χ)
Magnetic susceptibility is a measure of how easily a material can be magnetized in the presence of an external magnetic field.
It is defined as χ=M/H, where M is the magnetization and H is the magnetic field intensity.
Magnetic Dipole
A magnetic dipole is a pair of opposite magnetic charges (north and south poles) separated by a small distance.
Magnetic dipoles are found in elementary particles and also in macroscopic objects like magnets.
Magnetic Field Lines in a Bar Magnet
Magnetic field lines emerge from the north pole and enter the south pole in a bar magnet.
The field lines form closed loops and do not intersect.
Magnetic Field Inside and Outside a Bar Magnet
Inside a magnet, the magnetic field lines run from the south pole to the north pole.
Outside the magnet, the field lines follow a north-to-south direction.
Magnetic Field due to a Magnetic Dipole
The magnetic field at a point on the axial line of a magnetic dipole is given by Baxial=μ02m/4πr3, where m is the magnetic moment of the dipole and r is the distance from the dipole.
Bar Magnet as an Equivalent Solenoid
A bar magnet can be considered as equivalent to a solenoid when viewed from a distance.
The north pole of the bar magnet corresponds to the end from which field lines emerge in the equivalent solenoid.
Torque on a Magnetic Dipole in a Uniform Magnetic Field
A magnetic dipole experiences a torque (τ) when placed in a uniform magnetic field (B).
The torque is given by τ=m×B, where m is the magnetic moment of the dipole.
Para-, Dia-, and Ferromagnetism
Paramagnetism: Materials with unpaired electrons that align with an external magnetic field.
Diamagnetism: Materials with all paired electrons that slightly repel from an external magnetic field.
Ferromagnetism: Materials with a spontaneous alignment of magnetic dipoles, resulting in strong magnetization.
Curie Temperature
The Curie temperature is the temperature at which a ferromagnetic or ferrimagnetic material loses its magnetic properties.
Above this temperature, thermal agitation disrupts the alignment of magnetic domains.