Ohm’s law

Ohm's law is the main basic electrical
law and defines the resistance of a
device to the flow of electrons.

There are three different notations of
Ohm’s law

Unknown Current

Unknown Voltage

Unknown Resistance

(Most people can remember a picture
easier than a mathematical formula.
By knowing any two values you can
figure out the third. Simply put your
finger over the portion of the symbol
you are trying to figure out and you
have your formula).

Resistors in Series & Resistors in Parallel

Series Connection
A series circuit is one with all the loads
in a row. Like links in a chain. There is
only one path for the electricity to
flow.


Parallel Connection
A parallel circuit is one that has two or
more paths for the electricity to flow.
In other words, the loads are parallel
to each other.

Compilers vs Interpreters – Anoverview of the differences

It is a general notion that people try to
classify programming languages as
either “compiled” language or
“interpreted” language. Even
experienced programmers tend to get
confused here! But the fact is,
programming languages are
neither “compiled” nor
“interpreted” types. They can be
both at the same time. Compiling or
interpreting -both are 2 different ways
of implementing the same program
written using a programming
language. A program written in C
language can either be compiled or
can be interpreted. Same is the case
with Java or any other programming
languages. The only requirement is,
we need a C or Java compiler to
compile a C/Java program and
similarly we need an C/Java
Interpreter to interpret a program
written in C/Java. So the difference is
not with programming languages, it is
with the way programs written in
different languages are implemented.

Any one serious about programming
should understand the working of
compilers,interpreters and the
differences between them.So here I
am trying to outline generic
differences between compiling and
interpreting (compilers vs interpreters).

Though I said programs written in any
programming language can be either
compiled or interpreted, it is not the
case always. Theoretically what I wrote
above is right – any program can be
compiled/interpreted. But a
programming language is usually
developed with an orientation to one
particular form of execution – for
example- C language was designed to
be compiled where as Java was
designed to be interpreted. But there
are interpreters available for C
programs too which will be helpful as
debugging aids. But in most cases a C
program is compiled for execution
and not interpreted. Before going
through differences, keep in mind the
following technical terms.

Compile time– The time taken to
compile a program.

Run time– The time taken for
executing a program.

Source code- The program in its user
written form of the language. Source
code is given as input to the compiler.

Object code- is actually the machine
code which is obtained by converting
source code. The computer can read
and execute machine code directly.
An object code is also known as
binary code/machine code.

So the primary difference between a
compiler and interpreter is in the way
a program is executed. A compiler
reduces the source code to machine
code and then save it as an object
code before creating an executable
file for the same. When executed, the
compiled program is executed directly
using the machine code (object code).
Where as an interpreter does not
convert the source code to an object
code before execution. An interpreter
executes the source code line by line
and conversion to native code is
performed line by line while
execution is going on (at runtime). In
such a scenario, the run time
required for an interpreted program
will be high compared to a compiled
program. Even though the run time
required for interpreted program are
high, the execution using an
interpreter has its own advantages.
For example -interpreted programs
can modify themselves at runtime by
adding/changing functions. A
compiled program has to be
recompiled fully even for the small
modifications we make to a small
section of the program; where as an
in the case of an interpreter there is
no such problem (only the modified
section needs to be recompiled)

Let us summarize the advantages of
both implementation methods–
compiling and interpreting

Advantages of using compiler:-

• Since compiler converts the
  program to native code of the
  target machine (object code), faster
  performance can be expected.


• There is a scope for code
  optimisation.

Advantages of using interpreter:-

• Process of execution can be done
  in a single stage. There is no need
  of a compilation stage.


• Alteration of codes possible during
  runtime.


• Really useful for debugging the
  codes (because source code
  execution can be analyzed in an
  IDE).


• Facilitates interactive code
  development.

Norton & Thevenin theorem

Thé venin's Theorem

Any voltage network which may be
viewed from two terminals can be
replaced by a voltage-source
equivalent circuit comprising a single
voltage source E and a single series
resistance R.. The voltage V is the
open-circuit voltage between the two
terminals and the resistance Z is the
resistance of the network viewed from
the terminals with all voltage sources
removed from circuit.

Sample

All circuits are equivalent. Resistors
R₁,R₂, R₃ and voltage source are
transformed into Required Eq,

see parallel,
series simplifications.

To determine Eequ we shall break off
branch connecting node 1 and node
2

Norton's Theorem

Any current network which may be
viewed from two terminals can be
replaced by a current-source
equivalent circuit comprising a single
current source I and a single shunt
conductance G. The current I is the
short-circuit current between the two
terminals and the conductance G is
the conductance of the network
viewed from the terminals with all
branches containing current sources
are broken off.

Rainbow Versatile Disk –Future Storage device

The whole world always moves towards
the small size and high capacity
storage devices. But instead of
inventing a new storage device for our
future needs, there is a new
technique to store enormous amount
of data in nowhere else, but in a paper.
You can store an awesome amount of data about 250GB of data in just a sheet of A4 paper. This new technology is the ‘Rainbow ‘. Rainbow technology is the upcoming storage technology and it is currently in its developmental stage. So, how it is
done? Read below to find it out more..

Rainbow Versatile Disk

What’s behind it?
This technology uses geometric
shapes to store data instead of the
usual digital format of 0′s and 1′s. The
geometric shapes used to store data
also included Textures and Diagrams.
Development
Mr. Sainul Abideen, a Computer
Applications student of MES college of
Engineering – Kerala, India has
designed this Rainbow technology.
His design combines various
techniques to create an unique one.
Storing the data as geometric shapes,
we can compress data in 450 sheets
of plain text into a 1 inch square. Also.
the bits and bytes of a 45 second
audio clip can also be compressed on
to a A4 sheet. Based on the sampling
frequency, depth of bit and
compression of audio, the size of the
45 second audio clip can vary from
few kilo bytes to few mega bytes of
data.
The highly advantageous thing with
the Rainbow Technology is that, the
same principle can be extended up to
256 GB of data by using specific
materials and devices.
Rainbow Versatile Disc (RVD)
Data from 90GB to 450GB can be
stored in an RVD, which is 131 times
the capacity of a normal CD. RVD
supports the data in any format like
movie files, MP3 files, picture files,
data files, etc. Special drives need to
be developed in order to support
RVDs. A method called “Vertical
Lining” is applied in RVD.
How it’s done?
In Rainbow technology, the data in
any format termed ‘rainbow format'
has been designed in such a way that
it can be printed out in the form of
images. The data is converted to
rainbow format on the basis of
Rainbow Algorithm. Trigonometric
forms like circle or square, certain
color combinations and certain other
forms are being used. Each
trigonometric form, color
combination represents a complete
pattern.
Most modern technologies like image
processing, pattern matching, etc. are
used for the purpose. The data which
gets converted into an image form is
then printed on paper or any other
thing. This is how the data storage is
made possible. When the steps are
reversed, the rainbow picture is
converted into data.

This is how it’s done!

Although environmental light
differences and color shading is a
problem, it can be overcome up to a certain extent by using efficient
mapping function. Each rainbow
format contains a header, body,
footer, parity, Rainbow boundary
mapper, etc. Header contains the
measurement of the rainbow picture, the algorithm that is being used, etc. It
also contains an efficiently-designed
error checking system.
Pros
CDs are made using Poly
Carbonate which costs about Rs.
400 to Rs. 450 per kilogram and 16
Grams of Poly Carbonate is needed
to make a CD. But the RVD which
offers 131 times storage capacity
than the CD can be made from
paper.
It is highly portable and bio-
disposable.
Cons
Since it is made of paper, it can be
easily destroyed.
A scanner can reliably distinguish
256 unique colors and the scanner
which can distinguish 1,440,000
colors is costly.
Final Words…
Technologies like these will drag us
more towards it. In future, we will see RVD’s replacing DVD’s and Blu Ray Disks as the major storage device. To do that, it has to overcome it’s shortcomings. Let’s hope this environment friendly technology comes into our everyday computing life.

Dear Readers! Let us know your
thoughts about Rainbow Versatile
Disks through the comments!

Direct currents devices

Electrical Symbols

Electronic component are classed into
either being Passive devices or Active
devices. A Passive Device is one that
contributes no power gain to a circuit
or system. Examples are Resistors,
Light Bulb, Electrical Heaters. Active
Devices are components that are
capable of generating voltages or
currents. Examples are Batteries and
other Electrical Curent & Voltage
Sources.

By using schematics symbols we can
represent real-life devices.

Resistance -This is a resistance,
measured in units ohms ohms, . Most
often it will be a resistor.

This is a source of emf
(electromotive force) or voltage
source, with a voltage of , measured
in units of volts, V. The most common
source you will see will be a battery.
However, batteries are really not
resistance-free. We can model this
case by putting a 'resistor' in the
circuit which has the same resistance
as the batterys would have.

This is a current source, with a
current of , measured in units of
amperes , A. Current source is ideal
model of electrical power source. The
internal current source resistance is
infinity. We can model real life battery
by putting a 'resistor' in parallel with
curent source.

Voltage, Current & Resistance

In electronics we are dealing with
voltage, current and resistance in
circuits.
Voltage
Voltage is the electrical force, that
causes current to flow in a circuit. It is
measured in VOLTS .
Electrical Current
Current is the movement of electrical
charge - the flow of electrons other
charged particles through the
electronic circuit. The direction of a
current is opposite to electrons flow
direction. Current is measured in
AMPERES (AMPS, A ).
Resistance
Resistance causes an opposition to
the flow of electricity in a circuit. It is
used to control the amount of voltage
and/or amperage in a circuit. It is
measured in OHMS.
There is a relation between Voltage, Current & Resistance i.e ^V ⁄ _R=I

Superposition theorem

In a network with multiple voltage
sources, the current in any branch is
the sum of the currents which would
flow in that branch due to each
voltage source acting alone with all
other voltage sources replaced by
their internal impedances.
The goal of folowing text is to check
superposition theorem.

Step 1. Construct following circuit
using Circuit Magic then run Node
Voltage Analysis. (popular circuits
analysis technique). You can
alsocalculate currents using other
techniques.


Electrical scheme
Inital variables
R₂=10Ohms; R₁ =10Ohms;
R₃ =10Ohms;
E₁ =3V; E₃ =4V;
Solution
V₁ ·G₁₁=I₁₁
G₁₁=1/R₁ +1/R₂+1/R₃=0,3
I₁₁ =-E₁/R₁ -E₃ /R₃ =-0,7
0,3V 1 =-0,7
V₁ =-2,3333
V₂ =0
I₁ =(V₁ -V₂ +E₁)/R₁ =0,0666667
I₂=(V₁-V₂)/R₂ =-0,233333
I₃=(V₁-V₂+E₃ )/R₃=0,166667
These values are used to check
currents determined from
superposition theorem
Step 2. Remove a voltage source
from the third branch then run
Node Voltage Analysis.


Electrical scheme
Inital variables
R₂=10Ohms; R₁ =10Ohms;
R₃ =10Ohms;
E₁=3V;
Solution
V₁ ·G₁₁=I₁₁
G₁₁=1/R₁ +1/R₂ +1/R₃=0,3
I₁₁ =-E₁ /R₁ =-0,3
0,3V 1 =-0,3
V₁ =-1
V₂ =0
I₁(1) =(V₁ -V₂ +E₁)/R₁ =0,2
I₂(1) =(V₁ -V₂ )/R₂ =-0,1
I₃(1) =(V₁ -V₂ )/R₃ =-0,1
These values are used to
determine current from
superposition theorem.
Step 3. Remove a voltage source
from the first branch then run
Node Voltage Analysis.


Electrical scheme
Inital variables
R₂=10Ohms; R₁ =10Ohms;
R₃ =10Ohms;
E₃=4V;
Solution
V₁ ·G₁₁=I₁₁
G₁₁=1/R₁ +1/R₂ +1/R₃=0,3
I₁₁ =-E₃ /R₃ =-0,4
0,3V₁ =-0,4
V₁ =-1,3333
V₂ =0
I₁(2) =(V₁ -V₂ )/R₁ =-0,133333
I₂(2) =(V₁ -V₂ )/R₂ =-0,133333
I₃(2) =(V₁ -V₂ +E₃)/R₃ =0,266667
Superposition theorem checking
I₁ =I₁(1) +I₁(2) =0,2-0,133333=0,0666666
I₂ =I₂(1) +I₂(2) =-0,1-0,133333=-0,233333
I₃ =I₃(1) +I₃(2) ==-0,1+0,266667=0,166667

Kirchhoff's Current and Voltage Laws & circuit analysis sample

Kirchhoff's Current Law (KCL)
KCL states that the algebraic sum of
the currents in all the branches which
converge in a common node is equal
to zero
SI_in = SI_out
Kirchhoff's Voltage Law
Kirchhoff's Voltage Law states that the
algebraic sum of the voltages between
successive nodes in a closed path in
the network is equal to zero.
SE = SIR
Solution using Kirchhoff’s Voltage and
current laws
Steps to solve circuit by Kirchhoff’s
Laws.
1. Construct circuit with circuit magic
schematics editor.

Circuit sample from circuit magic

2. Construct loops. (See “creating
loop” section in user guide) Number
of loops (and number of Kirhhoff’s
Voltage laws equations) can be
determined using following formula.
Loop can not include branches with
current sources. Due current sources
resistance equal infinity.
Loop Number = Branch Number –
(Nodes Number –1) – Current sources
Number
3. Select Analyze->Solve by Kirhhoff’s
laws menu item
4. In dialog box press OK button. if no
warning shown.
5. Read solution.
Solution example from circuit magic.
Writing Kirchhoff current law for 3-1
nodes
(Note number of Kirchhoff current
laws equations equal Nodes Number
–1)
(Node 1)J₁+I3+I₄+I7=0
(Node 2)-J₁ +I₂ -I₄=0
Wrining Kirchoff voltage law for 5-1-
(3-1) loops
(Loop1) I₃·R₃ -I₇ ·R₅ =-E₂
(Loop2) I₂ ·R₂ -I₇ ·R₅ +I₄ ·R₄ =E₁ -E₂
Linear equations
I₃+I₄ +I₇ =-2
I₂ -I₄ =2
10I₃ -10I₇ =-10
11I₂ +10I₄ -10I₇ =-7
Equations solution
I₁ =2
I₂ =0,692
I₃ =-0,846
I₄ =-1,308
I₇ =0,154