# Magnetic Materials Flashcards

What is the symbol and definition for a magnetic dipole moment?

> Symbol: μm

A magnetic dipole moment is a vector for the direction and magnitude of magnetism produced by a very small current loop

What is the equation for a magnetic dipole moment? What are all the symbols?

μm = I × A × μn > μm = Magnetic dipole moment > I = Current > A = Area > μn = Unit vector perpendicular to loop

What will happen do the magnetic dipole moment when placed in a magnetic field?

The magnetic dipole moment will align with the magnetic field

How can the small current loop inside a material be described as?

A small bar magnet

What is a good example of a small current loop?

An atoms electrons and their spin

What happens in an atom that causes a NET magnetic moment

> Electrons spinning cause a magnetic moment to be produced.

Because electrons are usually paired and spin in opposite directions this causes the magnetic moment s to cancel out.

A net magnetic moment is produced when there is an unpaired electron around an atom

What is the equation for the magnetic moment caused by an electron?

μ[el] = μ[spin] + μ[orb]

What is the equation and the symbols for the magnetic field strength in the solenoid?

B0 = μ0 × n × I B0 = Magnetic field strength μ0 = Permeability of free space n = Number of turns per unit length I = Current

What happens to the magnetic field strength of a solenoid when a material is placed inside the loop?

The magnetic field strength changes from B0 to B

What is the vector M?

> The total magnetic dipole moment per unit of volume.

> Also known as the magnetisation vector

What is the equation for the magnetisation vector?

M = n[at] × μ[av]

How is the magnetisation vector similar to polarisation?

M = n[at] × μ[av] P = n[at] × p[av]

What is the equation for the total magnetic moment?

μ[tot] = M × Az M = Magnetic moment per unit volume A = Area z = Length

What is the other equation for the total magnetic moment?

μ[tot] = I[m] × n × z × A I[m] = Current on the surface n = Number of turns per unit length A = Area z = Length

What is the equation for the magnetisation vector?

M = n × I[m]

What is the equation for the magnetic field inside a solenoid when a material has been added? What does this show?

> B = B0 + μ0M

> The material in the field contributes to the magnitude of the magnetic field strength