ACTIVE AND PASSIVE ELEMENTS

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Nov 2, 2013 (3 years and 7 months ago)

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ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



ACTIVE AND PASSIVE
ELEMENTS

IN A CIRCUIT



3/21/2013

F.E CIS SEC.B

GROUP II


CS
-
114

NABIA WASEEM

CS
-
079

RABIYA WASEEM

CS
-
081

UMMUL AALA






THE REPORTS DESCRIBES THE TYPES OF ACTIVE AND PASSIVE ELEMENTS THAT
COMPLETES THE CIRCUIT AND THUS
ARE A PART OF CIRCUIT ANALYSIS.


ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B












TABLE OF
CONTENTS

S.NO

CONTENTS

DESCRIPTION

PAGE
NO:

1

INTRODUCTION





2

WHAT ARE ACTIVE ELEMENTS

*INDEPENDENT SOURCES







*DEPENDENT SOURCES







EXAMPLES

*GENERATORS

*BATTERIES

*OP
-
AMPS

*TRANSISTORS

*VACUUM TUBES



3

WHAT ARE PASSIVE ELEMENTS

*RESISTORS







*CAPACITORS







*INDUCTORS



4

ANSWERS TO POSSIBLE QUESTIONS





5

SOURCE USED(BIBLIOGRAPHY)













ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B




IN
TRODUCTION

IN THE NAME OF ALLAH THE MOST BENEFICENT AND THE MOST MERCIFUL

First of all, we, group II members, would like to thank MAM ARJUMAND for providing us with the
opportunity to work over the topic of circuit analysis and research on the topic of
ACTIVE AND
PASSIVE
elements that would enhance our abilities to better unders
tand the topic, thereby
solving circuits more easily.

Circuit analysis is a wider area or electrical engineering that deals
with circuit and the development of the circuits that actually runs at
the back of the system providing energy to many of the applia
nces and
other electrical elements attached. How the system works? How the
current we provide serves the elements attached? How much current
is sufficient for the circuit to function properly? Several questions like
these are answered in the study of circu
it analysis.

Circuit analysis is the process by which voltage or current is measured across the element.
All the
circuit elements can be categorized into two types: active and passive elements that play a salient role
in the circuit formation .these
elements contribute to the circuit by fulfilling the requirements needed
behind the objective of its development. They are connected by wires to form a closed path thus
allowing current to flow.

To establish a flow of charge in a closed path, it is necessa
ry to exert a kind of force on the electrons
that carries the charge known as the electromotive force. It can be a current or a voltage source.

This report describes a detailed study of what the active and passive elements are and how they
function and its

applications. It contains all the indispensable details about how these elements are
majorly controlling the working of the circuit. With the help of circuit representations, the
performance and behavior of any electrical/electronic device can be studied
in simple, accurate and
efficacious manner.









ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B




ACTIVE ELEMENTS:

What are active elements?

An active element is a component or a device in a circuit that is capable of generating or producing
energy. In

reality, energy is stored in the active elements

in non
-
electrical form that is then converted
into electrical
form. Active

elements can be categorized into current and
voltage sources as both
provide

a drive to the circuit and
manage

the flow in
it. Voltage

sources are those sources due to
which the
voltage

at the terminal is equal to the voltage present
internally. On

the other
hand,current
sources keep

the terminal current same to that of the internal
current. Thus

voltage sources have series
impedances which are relatively
same
, while current sourc
es would have shunt admittances almost
equals to zero.

In an ideal
voltage source the current from the source varies depending
upon

the
loadconnected.
Likewise

in an ideal current
source, the

voltage across the source varies depending on the circuit
parameters. However
, it is not possible practically to construct an ideal source.

Sources can be classified into two types: mainly independent sources and the dependent
sources. In

independent sources, the generated voltage or current
does not

rely on any
other circuit voltage or
current and the value is constant being
unaffected. Whereas
, dependent
sources have the voltage that
depends on any other circuit current or voltage.





ACTIVE ELEMENTS

DEPENDENT SOURCES

VCCS

VCVS


CCCS

CCVS

INDEPENDENT
SOURCES

VOLTAGE OR
CURRENT

ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B





INDEPENDENT SOURCES:

Independent sources are those that generate electrica
l energy. The output voltage of an
independent voltage or current source does not depend on any circuit element
i.e.

whatever
load or passive element is attached, its value of energy dissipation wills not alter.an ideal
voltage source has zero internal resistance and can never be short circuited.

Internal ideal current source has infinite internal resistance due to whic
h maximum voltage
drop is there and all of the current flows out into the circuit. It can never be open circuited.










V
-
I
CHARACTERISTIC S
OF PRACTICAL
VOLTAGE SOURCE

ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B





THE ABOVE TWO MENTIONED GRAPHS SHOWS HOW A PRACTICAL INDEPENDENT
CURRENT AND
VOLTAG
E SOURCE DIFFERS FROM THE IDEAL ONE.


DEPENDENT SOURCES:

Dependent sources, also referred to as controlled sources, do supple energy to
the circuit but they rely on any oth
er factor, either current or voltage, of source
for their functionality.

There are four further categories of how these dependent sources rely on other
independent source of the circuit or even any varying quantity such as current or
voltage across a
branch. These are usually representated b y a diamond shaped
source that shows that it is dependent.







V
-
I
CHARACTERISTICS
OF PRACTICAL
CURRENT SOURCE

ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



These descriptions are described as:



VOLTAGE CONTROLLED VOLTAGE SOURC
E



VOLTAGE CONTROLLED CURRENT SOURCE



CURRENT CONTROLLED CURRENT SOURCE



CURRENT
CO
NTROLLED VOLTAGE SOURCE

VOLTAGE CONTROLLED VOLTAGE SOURCE (VCVS)

A voltage controlled voltage source has its output a factor times to the voltage at
any other point on the circuit.

Vs=αVx

Where α is a constant and Vx is the voltage across any given
element.





V
OLTAGE
CONTROLLED
CURRENT
SOURCE (VCCS
)

A voltage controlled current source has its output a factor times to the voltage at
any other point on the circuit. The output is current

Is=βvx

Where β

is a constant and Vx is the voltage across any
given element
.






ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



C
URRENT CONTROLLED CURRENT SOURCE

(CCCS)

A current controlled current source gives an output that depends upon the
current

flowing through any part of the circuit.

The output current is

Is=γIx

Where γ is a constant and Ix is

the current across any given element.







CURRENT CONTROLLED VOLTAGE SOURCE:

A current controlled voltage source gives an
output

that depends upon the
current across any part of the circuit. The output voltage is

Vs=
μIx

Where μ is a constant and Ix is

the current flowing in the circuit taken into
consideration.





There are a number of active
elements that are both independent and dependent and so they contribute to the
contribute to the circuit by providing a flow into it.


ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



Some of them are mentioned

below:



Power supply

o

A.c

o

D.c

o

Batteries



Generators



Transformers



Transistors



Operational amplifier

And many more.


This report gives a brief description of how these elements function thus
completing the circuit.


POWER SUPPLY:

A power supply is a device
that supplies electric power to an electric
load. It controls the output voltage or current to a specific value; the
controlled value is held nearly constant despite variations in either load
current or voltage supplied by power supply’s energy source.



C
ommon examples of this include



Power

supplies that convert ac line voltage to dc voltage.



Energy storage devices such as batteries and fuel cells.



Electromechanical systems such as generators and alternators.



Solar power.

AC POWER SUPPLY

An ac power
supply typically takes the voltage from the main supply and
makes it to the desired voltage. It is actually the sinusoidal wave form
that comes as an input to the circuit.

DC POWER SUPPLY:

It a straight line wave form that is constant and is rectified form

of the
A.c supply. Batteries give D.c supply. Mobile phones operate on dc
supply.



ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



BATTERY:

A battery is a device that converts stored chemical energy to electrical
energy.
USES:

Energy sources in many household

Industrial applications.

There are two ty
pes of batteries: primary batteries (disposable batteries),
which are designed to be used once and discarded, and secondary
batteries (rechargeable batteries), which are designed to be recharged and
used multiple times.


Batteries come in many sizes, from
miniature cells used in hearing aids
and wristwatches to room
-
size battery banks that serve as backup power
supplies in telephone exchanges and computer data centers.














ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



GENERATORS:

Electric generator works over the principle of converting
mechanical energy,
provided by the external system, into electrical energy by the principle of
magnetic induction.

They provide power that runs machines in factories,
provides lighting, and operates homeappliances.



The size of large generators is usuall
y measured in kilowatts. One kilowatt
equals 1,000 watts.

There are two main types of generators.



Direct
-
current (DC) generators produce electric current that always flows in the
same direction.

Alternating
-
current (AC) generators, or alternators, prod
uce electric current that
reverses direction many times every second.

Both kinds of generators work on the same scientific principles. But they differ
in the ways they are built and used.













ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



TRANSFORMERS:

Transformers
works over the principle of

magnetic induction.there are

two types
of winding namely primary and secondary. When a current is supplied to the
primary winding a magnetic flux is generated in the coil and by the law of
magnetic induction and continuous change in magnetic flux, a volta
ge is
induced at the secondary coil which is used as the output.

The number of turns of the coil usually contributes by increasing or decreasing
the output voltage. This is known as:



Step up transformer: where voltage is increased
at the output terminal.



S
tep down transformer: that reduces the voltage at the output terminal.












ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



TRANSISTORS:

According to a website following description of transistor and its working is
shown.

http://www.cedengineering.com/upload/Transistors.pdf


Transistors are

semiconductors

found
everywhere in electronic circuits. They are used
as amplifiers and switching devices. As
amplifiers, they are used in high and low
frequency stages, oscillators, modulators,
detectors and in any circuit needing to perform a
function. In digital circ
uits they are used as
switches.

Being forward or reverse biased, a transistor
allows current to pass through or even opposes it
depending upon its placement. Moreover, it
depends upon the base current flowing.

Some types of transistors are:



Bipolar
junction transistor




Field
-

effect transistor



Diffusion transistor



Unijunction transistor, etc


ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



OPERATIONAL AMPLIFIER (op
-
amp):

An operational amplifier is a device used to compare between two voltages
being input into it and amplify
it.



It

is used as



A comparator

It compares the two voltages
that can be monitored in terms of
temperature change or light dependency as
well. It

involves the usage of
negative feedback where one output is used as an input next time.




Inverting amplifier

It uses negative
feedback but not all of the
output voltage is fed back into the inverting
input (
-
)




Non inverting amplifier

Here the input voltage is applied to the non
-
inverting
input; part

of the output voltage is
fed back to the inverting input.


Thus, by op
-
amp usage

the gain is increased to a higher value but it is
made sure that the overall gain is almost the same due to which distortion
is less and the signal remain constant for large frequencies as well.

Gơ=output voltage/input voltage


An ideal op
-
amp has the fol
lowing characteristics:

1.

Infinite open loop gain voltage
(no feedback used)

2.

Infinite input resistance(no current drawn from supply)

3.

Zero output resistance(no internal resistance no voltage drop)

4.

Infinite bandwidth(same over large frequencies)

5.

Infinite slew r
ate( time delay between input and output)

6.

Zero noise contribution






ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



PASSIVE ELEMENTS


A passive component only absorbs energy or absorbs energy then later releases
it.


Main three types of passive components are:

1.

Resistor

2.

Capacitor

3.

Inductor




RESISTANCE

Definition:

“The hindrance or opposition offered by the atoms of a conductor in the flow of
electric current is called Resistance.”

Or


“It is a ratio of the potential difference to the current.”

Symbol:

Resistance is designated by the symbol
R
.

Unit:

The unit of measurement for resistance is
ohms


.

Factors on which resistance depends:

The amount of resistance depends upon

1.

Length

2.

Cross
-
section

3.

Temperature

4.

Nature of the substances

OHM’S LAW DEFINES RESISTANCE:


In 19
th

century,
German mathematician, George Simon Ohm gave the following
law:
"Voltage across the conductor is directly proportional to the electric
current passes through a conductor."

V α I

V = I R

Relationship between current and voltage can be represented as,

ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B




Figure
1

v
-
I relationship of an ideal resistor



OHM’S LAW TRIANGLE

There is an easy way to remember which formula to use.


COMBINATION OF RESISTANCES:


1.

Serial Combination:



It is formed when any numbers of resistors are connected

in a circuit end
-
to
-
end so that there is only one path for current to flow



The total or equivalent resistance is always larger than the individual
resistance



Current is the same anywhere it is measured in a series circuit


Total or equivalent resistance (
R
eq
) can be calculated as,

R
eq
= R
1

+ R
2

+ R
3

+…………………







ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



2.

Parallel Combination:




It is formed when two or more resistances are placed side
-
by
-
side so that
current can flow through more than one path.



The total or equivalent resistance is always smaller

than any individual
resistance



Voltage is the same anywhere it is measured in a parallel circuit


Total or equivalent resistance (R
eq
) can be calculated as,























…………….

Circuit Symbol:

Two ways are:



Units of Measurement

Special prefixes that are commonly used when dealing with values of
resistance:


Prefix

Symbol


Decimal

1 kilo ohm

1 KΩ
=
1000 Ω
=
=
1 mega ohm

1 MΩ
=
1,000,000 Ω
=
=
=
=






ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



COLOR CODING:



















SOME OF THE DIFFERENT TYPES OF RESISTORS USED ARE:




Axial



Surface mount












ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B





CAPACITOR

Capacitor is made of two metal plates with separated by insulating material.
When a voltage is applied to the plates, electrons are forced onto one plate. The
plate with an excess of electrons is negatively charged.

The plate with a
deficiency of electrons is positively charged.






Symbol:

Capacitor is designated by the symbol
C
.

Unit:

The unit of measurement for
capacitor is
Farad (F)
.






Factors on which capacitance depend:

The amount of capacitor depends
upon

1.

Area of the plates

2.

Distance between the plates

3.

Material of the dielectric


Simple Capacitive Circuit

In the following circuit, initially the switch is open and no voltage is applied to
the

Capacitor and when the switch is closed, potential across the capacitor will rise
rapidly at first, then more slowly as the maximum value is approached.





ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



Combination of Capacitors:


1.

Serial Combination:



It is formed when any numbers of capacitors are
connected in a circuit
end
-
to
-
end so that there is only one path for current to flow



The total or equivalent capacitor is always smaller than the individual
capacitor



Current is the same anywhere it is measured in a series circuit


Total or equivalent resi
stance (C
eq
) can be calculated as,






















…………….




2.

Parallel Combination:




It is formed when two or more capacitors are placed side
-
by
-
side so that
current can flow through more than one path



The total or equivalent capacitor is

always larger than any individual
capacitor



Voltage is the same anywhere it is measured in a parallel circuit


Total or equivalent resistance (C
eq
) can be calculated as,

C
eq
= C
1

+ C
2

+ C
3

+…………………




Circuit Symbol:

Two ways are:







ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B





INDUCTOR

Definition:

Inductance is the property of an electric circuit that opposes any change in
electric current.

Inductance opposes change in current flow.


Symbol:


Inductance is designated by the letter “L”.


Unit:

The unit of measurement for inductance is t
he
Henry (H).


Expression:

The relationship between the time varying voltage across an inductor L and time
varying current passing through it can be expressed as,


V (
t) = L









Factors on which inductance depend:

The amount of inductance
depends upon

1.

Number of turns in the coil

2.

Spacing between the turns

3.

Coil diameter

4.

Core material

5.

Type of winding


Examples:

Examples are:

1.

Transformers

2.

Chokes

3.

Motors

Simple Inductive Circuit

If an inductor is used, the current does not
change as quickly. In the following circuit,
initially the switch is open and there is no current
flow and when the switch is closed, current will
rise rapidly at first, then more slowly as the maximum value is
approached.


ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



Circuit Symbol:

Two ways are:






Combination of Inductances:


1.

Serial Combination:



It is formed when any numbers of inductors are connected in a circuit
end
-
to
-
end so that there is only one path for current to flow



The total or equivalent
inductance is always larger than the individual
inductance



Current is the same anywhere it is measured in a series circuit


Total or equivalent resistance (L
eq
) can be calculated as,

L
eq
= L
1

+ L
2

+ L
3

+…………………


2.

Parallel Combination:




It is formed when
two or more inductance are placed side
-
by
-
side so that
current can flow through more than one path



The total or equivalent inductance is always smaller than any individual
resistance



Voltage is the same anywhere it is measured in a parallel circuit


Total
or equivalent resistance (L
eq
) can be calculated as,























…………….







ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



DIFFERENCES BETWEEN ACTIVE AND PASSIVE ELEMENTS:

Some of the differences between these elements are described below. Both
contribute a lot to the
circuitry and thus to many of the electrical and electronic
revolutions that has taken place but the ways they differ are mentioned below:


ACTIVE
ELEMENTS

control the flow of
electric energy within
the circuit

does not depend on
other elements for
operations

there should be a
power source for its
working

active elements cannot
store energy.

PASSIVE
ELEMENTS

depends on others for
elements

dissipate or store the
electric energy

don't require power
from the supply to
produce its effect on a
signal

Some passive
components also have
the capability to store
energy and release
later

ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



DESPITE OF THESE DIFFERENCES, ONE CANNOT DENY THE
IMPORTANCE OF ACTIVE AND PASSIVE ELEMENTS IN
TODAY’S LIFE.

THEREF
ORE, SOME OF THE CONTRIBUTION AND HOW IT
CARRIES WEIGHT ARE DESCRIBED BELOW:












ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B



BIBLIOGRAPHY:

http://en.wikipedia.org/wiki/Power_supplies

http://www.google.com.pk/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1024&bih=630&
q=dependent+sources+in+a+circuit&oq=dependent+sources+in+a+circuit&gs_l=img.3...179.7353.0.7
561.30.18.0.12.12.2.280.2221.9j4j5.18.0...0.0...1ac.1.7.img.4lXT9TJ5FuE

http://www.google.com.pk/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1024&bih=630&
q=dependent+sources+in+a+circuit&oq=dependent+sources+in+a+circuit&gs_l=img.3...179.7353.0.7
561.30.18.0.12.12.2.280.2221.9j4j5.18.0...0.0...1ac.1.7.img.4lXT9TJ5Fu
E

http://en.wikipedia.org/wiki/Electronic_component

BASIC ELECTRICAL ENGG BY S.N SINGH

AS AND A LEVEL PHYSICS BY DAVID SANG,GRAHAM JONES,RICHARD WOODSIDE AND GURINDER
CHADHA.

http://www.differencebetween.com/difference
-
between
-
active
-
and
-
vs
-
passive
-
components/#ixzz2O5BFGRSo

http://www.eie.polyu.edu.hk/~cktse/linear_circuits/main/node6.html

http://www.google.com.pk/#hl=en&sclient=psy
-
ab&q=examples+of+independent+sources+in+a+circuits&o
q=examples+of+independent+sources+in
+a+circ&gs_l=serp.3.0.33i29i30.2420.7051.0.9122.10.10.0.0.0.0.2874.9209.3
-
5j6
-
1j3j0j1.10.0...0.0...1c.1.7.psy
-
ab.zUzaEiILvfk&pbx=1&fp=1&biw=1024&bih=630&bav=on.2,or.r_qf.&cad=b

http://www.electrical4u.com/ideal
-
dependent
-
independent
-
voltage
-
current
-
source/

http://wiki.answers.co
m/Q/What_is_the_Difference_between_active_and_passive_elements

http://www.oocities.org/electricgenerator/

http://en.wikipedia.org/wiki/Trans
former

http://www.google.co
m.pk/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1024&bih=630&
q=op
-
amp&oq=op
-
amp&gs_l=img.3..0l8j0i24l2.1968.5246.0.5870.8.8.0.0.0.0.787.1900.0j2j4
-
2j0j1.5.0...0.0...1ac.1.7.img.sqezlu2x94c

http://www.google.com.pk/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1024&bih=630&
q=RESISTOR
&oq=RESISTOR&gs_l=img.3..0l10.6597.8109.0.8654.8.8.0.0.0.0.410.822.0j1j1j0j1.3.0...0.
0...1ac.1.7.img.f1iJUab2QXg

https://www.google.com.pk/

ACTIVE AND PASSIVE ELEMENTS IN A CIRCUIT


GROUP II

SEC B