ElectromagnetismUniversity of British ColumbiaPhysics 420By: Jason Cheung

What is a Field?A region of space characterized by a physical property having a determinable value at every point in the regionExamples: gravitational field, Electric field ,and magnetic field

Gravitational FieldDefined as A = accelerationG = gravitational constant m = mass of big objectr = distance to the center of the big object

Electric FieldElectric field is defined as the electric force per unit Charge

It is the surrounding charges that create an electric fieldE = Electric FieldF = Electric Forceq = Charge E is measure in Force/Coulomb

Cathode Ray Tube Demo (CRT)

Magnetic FieldMagnetic field is a field that exerts a force on a moving chargeA magnetic field can be caused either by another moving charge or by a changing of electric field or magnetic dipoles of materials

Magnetic Field is measure in Tesla

A simple formula to calculate Magnetic FieldB = magnetic fieldF = Magnetic ForceQ = chargeV =velocity of the moving charge

Battery Demo

Charge moving in a magnetic field obeys the Right Hand RuleThere are two types of RHRRight Hand Rule #1Right Hand Rule #2

Right Hand Rule 1The thumb represents the velocity of which the charge is goingThe remaining fingers tell you the direction of the magnetic fieldexample:

Right Hand Rule 2I = direction of the chargeB = direction of the Magnetic FieldF = Force act on the chargePalm Push Positive (*Remember!!)

Right Hand Rule Question

Magnetismexample of pair and unpaired: N is unpaired, O is paired (one of them)What is magnetism?Magnetism is one of the phenomena by which materials exert an attractive or repulsive force on other materials. What causes magnetism in material?It is the unpaired electrons in the electron orbit cause magnetism

Remember SPDF?? (Chem 11)Electrons fall into electron shell according to Hunds rule. Examples

Nitrogen-Electrons-Protons and Neutrons1s22p3Electron Configuration of NitrogenWrongWrong2s2Right

There are four types of magnetism

1.Ferromagnetic2.Paramagnetic3.Diamagnetic4.Ferrimagnetic(Not going to cover)

Magnetism is Measure in Magnetic Susceptibility (m) The more susceptibility of a material has, the more magnetic property it processes

MaterialSusceptibility mVacuum0Water-1.2*10-5 Bi-16.6*10-5C-2.1*10-5O20.19*10-5Al2.2*10-5Fe200 Co70 Ni110

FerromagneticAny material that possess magnetization WITHOUT an external magnetic field is ferromagneticlarge and positive susceptibility Examples of ferromagnetic materialsCobalt (Co)Susceptibility = 70

Iron (Fe)Susceptibility = 200

Iron electron configurationFe: 1s2,2s2,2p6,3s2,3p6,4s2,3d6 Fe: [Ar],4s2,3d6 Ar: 1s2,2s2,2p6,3s2,3p6 = [Ar] Core[Ar]-The electrons seems to align spontaneously-Pure quantum mechanics effect

Why are some Ferromagnetic doesnt attract one another?Has to do with the magnetic domain of the material

Ferromagnetic material demo

ParamagneticAny material that possess magnetization (i.e. attraction with other magnetized material) WITH an external magnetic field is paramagneticsmall and positive susceptibility Examples of paramagnetic materials

Aluminum AlSusceptibility = 2.2*10-5 Platinum Pt

Aluminum electron configuration[Ne].3s2.3p1 Compare to Iron (Fe)[Ar]Fe: [Ar],4s2,3d6the dipoles do not interact with one another and are randomly oriented in the absence of an external field due to thermal agitation, resulting in zero net magnetic moment What is the differences between the two?!

Paramagnetic and Ferromagnetic Demo (magnets and levitation)

Diamagneticvery weak and negative susceptibility to magnetic fields. Negative susceptibility = repel against magnetic fields (diamagnetism)Positive susceptibility = attract to magnetic fields (para + ferromagnetism)

DiamagnetismExamples of diamagnetic materials

GoldCopperHuman (mostly)

Diamagnetic Levitation Demo

Applications of MagnetismMRI (magnetic resonance images)Superconductors

Applications of MagnetismMaglev Trains

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