Welcome to Physics 321

My Name is Brett Fadem

What is Electrodynamics and How Does it Fit

Into The General Scheme of Physics?

First, what is the distinction between kinematics and dynamics?

KinematicsKinematics is the study of motion without regard to the cause. Kinesis is the Greek word for motion.

DynamicsDynamics is the study of the causes of motion. Dunamis is the Greek word for power. We call theCauses of motion, “forces.”

Source: The Dr. Physics Homepage. Please include attributions in your work.

The Distinction between Kinematics and Dynamics.

So, “electrodynamics” is the study of the electric and magnetic causes of motion

(or, electric and magnetic forces).

But what part of physics studies the resulting motion of objects

When acted upon by a force?

Mechanics!

Describe the force and mechanics will tell you how things move.

Newton’s Laws

1st Law

2nd Law

3rd Law

Objects in motion, remain in motion. Objectsat rest remain at rest.

2112 FF

2

2

dt

rdm

dt

pdamF

What do you remember from classical mechanics?

1 2

Relativistic Corrections?

vtxx

yy

zz

tt

)( vtxx

)( 2cvxtt

yy

zz

Galilean Transformations Lorentz Transformations

Special Relativity

vmp

vmp

2

2

1mvKE 2)1( mcKE

2)(1

1

cv

Classical Mechanics Quantum Mechanics

Special Relativity Quantum Field Theory

(Newton: 1642-1727) (Bohr, Heisenberg, Schrodinger, et al.)

(Einstein. 1905 was a big year.)

(Dirac, Pauli, Feynman, Schwinger, et al.)

The Four Forces to Which Mechanics is Applied:

1. Strong

2. Electromagnetic: complete theory in all 4 realms!

3. Weak

4. Gravitational

So, electrodynamics is the study of the electromagnetic force, and

mechanics tells us how a system will behave when subjected to that

force.

Electricity

Magnetism

Weak Force

Strong Force?

Gravity ??

Unification?

Electromagnetism Electroweak

Quantum Chromodynamics “QCD”

“QED”

General Relativity

“In this Course, we are going to focus on classical electromagnetism, that is, electromagnetism in the

context of classical physics.”

Comparison of Strength of Electromagnetic vs. GravitationalForce

221

r

mmGFG

221

04

1

r

qqFEM

2272

211

219

2

212

2

2

2

2

2

2

)1067.1)(1067.6(

)106.1()1085.8(4

1

41

41

KgKgNm

C

NmC

Gm

e

r

mG

re

F

F

p

o

p

o

G

EM

36102.1 G

EM

F

FElectromagnetism is much stronger!

mp=1.67x10-27 Kg

e =1.6x10-19 C

εo=8.85x10-12 C2/(Nm2)

G=6.67x10-11 (Nm2)/Kg2

o

enc

S

QadE

0S adB

dt

dldE

encoIldB

o

E

0 B

t

BE

t

EJB ooo

Maxwell’s Equations

Gauss’s Law

Faraday’s Law

Ampere’s Law

For Each of Maxwell’s Equations, you should have a simple picture

in your mind.

o

enc

S

QadE

Gauss’s Law

Ampere’s Law

encoIldB

dt

dldE

Faraday’s Law

adB

0 E

0 B

t

BE

t

EB oo

)()()( 2

t

BEEE

(i)

(ii)

(iii)

(iv)

2)(

t

EB

t oo

Maxwell’s Equations in Vacuum

Take the curl of the curl, etc.

2

2

22 1

t

E

cE

And, you know who said, “Let There Be Light!”

The Electric FieldDivergence and Curl of Electrostatic FieldsElectric PotentialWork and Energy in ElectrostaticsConductors

Chapter 1Vector AnalysisVector AnalysisDifferential CalculusIntegral CalculusCurvilinear CoordinatesThe Dirac Delta FunctionThe Theory of Vector Fields

Chapter 2Electrostatics

Chapter 3Special TechniquesLaplace’s EquationThe Method of ImagesSeparation of VariablesMultipole Expansions

Chapter 4Electric Fields in MatterPolarizationThe Field of a Polarized ObjectThe Electric DisplacementLinear Dielectrics

Chapter 5Magnetostatics

The Lorentz Force LawThe Biot Savart LawThe Divergence and Curl of BMagnetic Vector Potential

Chapter 6Magnetic Fields in MatterMagnetizationField of a Magnetized ObjectAuxiliary Field HLinear and Nonlinear Media

Chapter 7 Electrodynamics

Electromotive ForceElectromagnetic InductionMaxwell’s Equations

Introduction to Electrodynamics