Download Electromagnetica Aplicada - Electrical and Computer Engineering

Inductance and Capacitance
INEL 4075 –Chapter 7
Dr. Sandra Cruz-Pol
Professor
Electrical & Computer Engineering
UPRM
Capacitors
Capacitors store electrons in form
of separated charge or E field.
http://www.kpsec.freeuk.com/components/led.htm
Capacitance, in Farads [F]
•The capacitance is
C
•The charge
A
d
q  Cv
•The current in a capacitor
dv
iC
dt
•The voltage, cannot change
instantaneously
t
1
v   i d
C 
Capacitors
•Energy stored in capacitor
t
w(t )   vi d

1 2
w(t )  Cv (t )
2
•Parallel and Series capacitors
N
C
tot
p
  Cn
n 1
N
1
1

tot
Cs
n 1 C n
Electric Circuit
Discharging a capacitor
Charge/discharge Capacitor
Piezoelectric
material
Chip – (integrated circuits)
The 555 timer regulator pin layout (from http://www.doctronics.co.uk/555.htm)
1k
C (mF)
Frequency
(Hz)
C1
.100
111
C2
.068
170
C3
.047
230
C4
.033
348
C5
.022
490
C6
.015
718
C7
.010
1,173
What is a circuit Board?
Nodes?
Myth: Why is the Ocean Blue?
FALSE: The ocean is blue
because the sky reflection on
its surface.
TRUE: Water is blue.
frequency spectra
But you need a huge
amount of it to really see its
color.
Look at a swimming pool as
it gets deeper; even on
cloudy days.
http://ece.uprm.edu/~pol/OceanBlue.html
Myth #2
•
•
FALSE: Thomas Edison, greatest contributor to
Electricity and systems used today.
TRUE: Nikola Tesla – greatest contributor to Electricity.
 Invented ac motor,
 perfected dc motor,
 invented radio transmission, (wireless)
 designed Niagara Falls generator,
 distribution systems,
 fluorescence lamps,
 remote control, wireless,
 logic circuits,
 3 phasic and many others.
Inductors
Symbol
• Store magnetic fields
Inductors
• Energy storage – inductors store energy
in the form of a magnetic field
• Series and parallel inductance
• Initial conditions of switch circuits
solenoid
Inductance, in Henries [H]
•The inductance is
L
mo N 2 A
l  .45d
•The voltage in an inductor
di
vL
dt
d
vN
dt
•The current, cannot change instantaneously
t
1
i   v d  i (to )
L to
Inductors
•Energy stored in inductor
t
w(t )   vi d

1 2
w  Li
2
•Series and Parallel inductors
N
L   Cn
tot
s
n 1
N
1
1

tot
Lp
n 1 Cn
Electro-magnet
***Warning!! It can get HOT.
Where to find this material?
• http://ece.uprm.edu/~pol/cursos