Magnetic Materials

Question 1

What is the magnetic dipole moment?

Answer 1

μ=IAn(hat)

Question 2

What is the torque for a magnetic dipole?

Answer 2

τ=μxB_0

Question 3

What is the magnetic field inside a material?

Answer 3

B=μr B_0
Where μr is the relative permeability

Question 4

What is a diamagnetic?

Answer 4

For which μr is<1 and the magnetic field is reduced inside the material

Question 5

What is a paramagnetic?

Answer 5

μr>1 and so the magnetic field is increased within the material

Question 6

What is the magnetisation vector for bound currents?

Answer 6

M=1/V ∑μ_j
With μ_j the magnetic dipole moment and V the volume

Question 7

What is the magnetic susceptibility?

Answer 7

χ_m=1-μ_r

Question 8

What is a ferromagnetic?

Answer 8

μ_r»1 so the magnetic field is greatly increased

Question 9

What is a hard ferromagnetic?

Answer 9

A permanent magnet which maintains a magnetic field even when there is no external magnetic field applied
Hence μ_r cannot be defined