ELE401-Review
Provide definitions or explain the meaning of the following terms:
2.0
The Static Electric Field
-
Coulomb’s law
-
Definition of Electric field intensity, E
-
Electric field Intensity, E, due to
o Line charge
o Surface charge
o Volume charge
-
Electric flux Density, D
-
Gauss’s law
Gauss’s law in point form
E-field solved by Gauss’s law
o point charge
o infinite line charge
o surface charge
o uniformly charged sphere
-
-
Electric potential, V
o Definition
o Potential gradient
V-field calculated from charge distribution
Electric dipole
Electric flux line
-
Energy density of an electric field
F12 
Q1 Q2
4  0 R 2
F
E  lim
Q 0 Q
E12  
a R12
 l dl
aR
4  0 R 2
3.0
Electric Fields in Material Space
-
Conductor and insulator, σ
Current and current density
o conduction current
o convection current
Ohm’s law
Joule’s law
Power density
Procedure of finding resistance R
-
Polarization in Dielectric
o Bound surfaced charge density, ps
o Bound volume charge density, pv
o D in dielectrics
o Polarization, P
o Electric susceptibility, χe
o Electric permittivity, ε
o Relative electric permittivity, εr
o Dielectric strength
-
Continuity equation
Relaxation time
-
Boundary conditions
o Normal components
o Tangential components
o Conductor-dielectric boundary
4.0
Electrostatic Boundary Value Problems
-
Poisson’s Eq.
 2V  
-
Laplace’s Eq.
V 0
-
Boundary-value problems
o Differential eq.;
o Field region;
o Boundary conditions
-
Procedure of solving a boundary problem
o Solve differential eq.
o Apply boundary conditions to find constants
E   V
o Find E from
D  E
o Find D from
 s  Dn (ρs-free surface charge density)
o If required find
o Find Q by
Q    s dS
v

2
s
(also the procedure of determining C by assuming V and find Q)
-
The Capacitance
C  Q /V
(assuming Q and find V)
o
o
o
o
o
-
Choose a suitable coordinates
Let conducting plates carry +Q and –Q
Determine E using Coulomb’s or Gauss’s law
V   E d l
Find V form
Obtain C from C=Q/V
Method of Image
Replacing the charge configuration by itself, its image and an
equipotential surface in the place of the conducting plane
-
5.0
-
Definition of H-field :
-
Biot-Savart’s law
dH 
-
H-field from a circular current loop
H
-
Ampere’s circuital law
o Infinitive line current
 H d l  I enc
…
1
H  K  an
2
-
The Magnetic Field
Fm  q u  B
Id l  R
,
R  r  r'
4 R 3
I
H-field from a finite line current
H
(cos 2  cos1 ) a
4 
I
H-field from an infinitive line current H 
a
2 
o Infinitive sheet of current
o Coaxial cable
I2
az
2 (  2  h 2 )3/ 2
I
, a
2 a 2
I
H 
, a b
2 
H 
H  0 ,
-
-
 b
Two Examples
o
Solenoid
o
Toroid
Magnetic flux density
Magnetic flux
NI
az
l
NI
H
az
2  0
H
B  0 H
   B dS
s
-
Non-existence of magnetic monopole   B  0 , or sBd S  0
Maxwell’s Eqs. (point and integral forms)
 Idl
A  0
Magnetic vector potential A
L 4 R
B   A,
 2 A   0 J
6.0
Magnetic Forces, material and devices
-
Magnetic flux density B in term of I∙dl
Lorentz force Eq.
Force on a current loop
Magnetic dipole moment
Magnetic torque
o General definition
o In term of magnetic dipole moment
-
Magnetization in Materials
o Atomic model of magnetic dipoles
A-field due to a magnetic dipole
Magnetization vector M
o The bound volume current density Jb
o The bound surface current density Kb
o Magnetic susceptibility χm
-
-
Magnetic boundary conditions
o Normal components
o Tangential components
-
Self-inductance
o A magnetic flux linkage
o Definition of inductance
o Magnetic energy stored in an inductor
Mutual-inductance
-
-
Procedure of calculating self-inductance L
o
o
o
o
Internal inductance
External inductance
-
Magnetic energy in a Magnetic field
-
7.0
Time-Varying Fields and Maxwell’s Equations
- Faraday’s law;
- Electromotive force Vemf
o Transformer emf
o Motional emf
- Lenz’s law
- Faraday’s law-point form
- Displacement current
- Maxwell’s Eqs - point form
- Maxwell’s Eqs - integral form
- Derivation of Wave Eqs. from Maxwell’s Eqs.
- Solutions of Wave Eqs. In free space;
o Phase
o Angular frequency
o Wavelength
o Period
o Wave velocity
o Forward and backward propagating wave
o spectrum