Lecture 10 Flashcards
Describe the shape of an M-H curve for a diamagnetic material
An increasing applied magnetic field induces an ___ in any material.
EMF
State Lenz’s Law
Induced electric currents produce a magnetic field in the opposite direction to the applied field.
Where does diamagnetism originate from?
At the atomic level, orbital motion is induced by an applied magnetic field and the resulting magnetic moments persist even when the applied field is constant.
Give the classical equation for angular momentum
L = angular momentum
m = mass
v = velocity
r = radius
What is the direction of angular momentum?
Clockwise when looking along L (follow the right hand rule)
Give the equation for the magnetic moment of an electron orbiting an atom
µ = magnetic moment
i = current
A = area
What is the magnetic moment of an electron orbiting an atom equivalent to?
The magnetic moment of a current loop
What is the direction of magnetic moment?
The current is clockwise then looking along µ (follow the right hand rule where the thumb is the current and the fingers are µ).
Give the equation for the magnetic moment of an electron orbiting an atom in terms of the angular momentum
µ = magnetic moment
L = angular momentum
How is the electric field due to an electron orbiting an atom calculated?
By using Faraday’s law to integrate around the closed circular path of an electron to find the total electric field of the orbit.
Give the equation for the electric field generated by an electron exhibiting orbital motion
E = electric field
r = radius of orbit
B = magnetic field
t = time
Give the equation for the induced magnetic moment due to the induced motion of an electron
µ = magnetic moment
B = magnetic field
Give the equation for the magnetism of a material with N atoms per metre-cubed and Z electrons per atom
M = magnetism
N = number density of atoms
Z = number of electrons per atom
ρ = distance of an electron from the z-axis
B = magnetic field
Give the equation for the magnetic susceptibility of a material with N atoms per metre-cubed and Z electrons per atom
χ = magnetic susceptibility
M = magnetism
B = magnetic field
N = number density of atoms
Z = number of electrons per atom
ρ = distance of an electron from the z-axis
Give the equation for the magnitude of magnetic susceptibility of a material with N atoms per metre-cubed and Z electrons per atom
χ = magnetic susceptibility
N = number density of atoms
Z = number of electrons per atom
a_B = Bohr radius
m_e = electron mass
