(Please Download From Below Link And Extract It Friends Using Winrar Or Winzip Or 7zip Softwares)
An Important And Complete Useful Stuff...
Wednesday, December 26, 2012
Friday, September 21, 2012
Is it safe to drink water from plastic bottles?
Get the best result from below link..
http://www.abc.net.au/health/talkinghealth/factbuster/stories/2010/10/27/3048695.htm#.UFybRJFF_iR
Monday, September 10, 2012
WEB SITES
Other Usefull Sites Are:
These sites are very very useful for Aptitude questions check it......
http://www.indiabix.com/
http://www.m4maths.com/
By
Admin
MokiAccenture Campus Interview
Hi I attended campus at VIT on 09-09-2012.
Rounds are:
1.Written.
2.Technical Interview.
3.HR Interview.
In written exam 3 parts were there,
1.English Ability
25 questions were there you have to finish it in 25 minutes.
Mostly synonyms,antonyms,preposition were asked.
2.Analytical Ability
25 questions and timing is 35 minutes. (Quantitative Aptitude R.S. Agarwal is more than enough).
3.Logical Ability
25 questions and timing 35 minutes. ( Easy part only presence of mind is enough).
Now i am waiting for the result...
I hope this may help you some how.
Saturday, September 8, 2012
EEE Basics
BASIC ELECTRICAL CONCEPTS:
BASIC ELECTRICAL CONCEPTS
Basic electrical concepts
In
each plant, the mechanical movement of different equipments is caused
by an electric prime mover (motor). Electrical power is derived from
either utilities or internal generators and is distributed through
transformers to deliver usable voltage levels.
Electricity is found in two common forms:
• AC (alternating current)
• DC (direct current).
Electrical
equipments can run on either of the AC/DC forms of electrical energies.
The selection of energy source for equipment depends on its application
requirements. Each energy source has its own merits and demerits.
Industrial
AC voltage levels are roughly defined as LV (low voltage) and HV (high
voltage) with frequency of 50–60 Hz. An electrical circuit has the
following three basic components irrespective of its electrical energy
form:
• Voltage (volts)
• Ampere (amps)
• Resistance (ohms).
1. Voltage is defined as the electrical potential difference that causes electrons to flow.
2. Current is defined as the flow of electrons and is measured in amperes.
3. Resistance is defined as the opposition to the flow of electrons and is measured in ohms.
All three are bound together with Ohm’s law, which gives the following relation between the three:
- V = I × R
(a) Power
In DC circuits, power (watts) is simply a product of voltage and current.
- P =V × I
For
AC circuits, the formula holds true for purely resistive circuits;
however, for the following types of AC circuits, power is not just a
product of voltage and current.
Apparent power
is the product of voltage and ampere, i.e., VA or kVA is known as
apparent power. Apparent power is total power supplied to a circuit
inclusive of the true and reactive power.
Real power or true power is the power that can be converted into work and is measured in watts
Reactive power If
the circuit is of an inductive or capacitive type, then the reactive
component consumes power and cannot be converted into work. This is
known as reactive power and is denoted by the unit VAR.
(b) Relationship between powers
- Apparent power (VA) = V × A
- True power (Watts) = VA × cosφ
- Reactive power (VAR) = VA × sinφ
(c) Power factor
Power
factor is defined as the ratio of real power to apparent power. The
maximum value it can carry is either 1 or 100(%), which would be
obtained in a purely resistive circuit.
- Power factor = True power / Apparent power
Types of circuits
There are only two types of electrical circuits – series and parallel.
A series circuit
is defined as a circuit in which the elements in a series carry the
same current, while voltage drop across each may be different.
A parallel circuit is defined as a circuit in which the elements in parallel have the same voltage, but the currents may be different.
Transformer
A transformer is a device that transforms voltage from one level to another. Transformer working is based on mutual emf induction
between two coils, which are magnetically coupled. When an AC voltage
is applied to one of the windings (called as the primary), it produces
alternating magnetic flux in the core made of magnetic material (usually
some form of steel). The flux is produced by a small magnetizing
current which flows through the winding. The alternating magnetic flux
induces an electromotive force (EMF) in the secondary winding
magnetically linked with the same core and appears as
a voltage
across the terminals of this winding. Cold rolled grain oriented (CRGO)
steel is used as the core material to provide a low reluctance, low loss
flux path. The steel is in the form of varnished laminations to reduce
eddy current flow and losses on account of this.
There
is a very simple and straight relationship between the potential across
the primary coil and the potential induced in the secondary coil. The
ratio of the primary potential to the secondary potential is the ratio
of the number
of turns in each and is represented as follows:
- N1/N2 = V1/V2
Current-induced
When the transformer is loaded, then the current is inversely proportional to the voltages and is represented as follows:
- N1/N2 = V1/V2= I2/I1
By
Admin
Moki Basic Concepts Of EEE
Before you start working with circuits, you need to understand the main concepts upon which the core of electrical engineering lies. Understanding the basics will help you keep up with the material and reduce the number of errors you make in the future. While there are some very important equations that you need to know, circuit analysis is not simply a matter of plugging numbers into an equation. You need to understand what voltage, current, and resistance is, and how they relate to each other in order to take advantage of those equations and understand what’s really going on in the circuit. This article will introduce you to the most basic concepts.
Engineering Notation
In this course and many other courses in the department, we want you to work with engineering notation. Scientific notation is useful for very small or very large numbers. However, you should use and familiarize yourself with engineering notation for all other numbers. Some common engineering prefixes are shown in the table below.
Electric Charge
You know that an atom, in its neutral state, has a charge of zero. You also know that if a neutral atom gains an electron, it becomes an ion with a charge of 1-. This definition of charge works fine when talking about one atom, but when working with large numbers of atoms, a more practical definition of charge is needed, i.e. electric charge. The unit for electric charge (denoted by the letter ‘q’) is the Coulomb (C). When measured in Coulombs, an electron has a charge of approximately -1.60 × 10−19 C. A proton, then, would have a charge of +1.60 × 10−19 C.Example: Find the charge of 5.1×1018 ions of copper (Cu). Each copper ion has a charge of 2+.
Solution: The copper ions have a surplus of protons, which means that the copper will have a positive charge. Multiply the fundamental charge of each ion times the number of ions. This gives the number of extra protons. Now multiply the number of extra protons by the charge, in Coulombs, of a proton.
q = 2 x 5.1 x
x 1.60x
= 1.63 CCoulomb’s Law
Coulomb’s law defines the magnitude of the force between two charges as:
where q1 and q2 are the two charges in Coulombs, r is the distance between the two points in meters, and the permittivity constant of free space is equal to 8.85 × 10−12 F/m (Farads/meter). If the force is negative, the two charges attract each other while a positive force means the two charges repel each other. The constant
is known as the electrostatic constant Kc, where
Note: Newtons (N) are a unit of force.
If you’ve ever experimented with magnets, then you have witnessed this law before. Two magnets repel and attract each other depending on the orientation of their poles. This equation also shows that the force between two charges grows exponentially as they move together because of the r2 in the denominator. You may have noticed this phenomenon as well. Two magnets attract or repel each other when placed very close together, but the force between them dies off rather quickly as they’re pulled apart.
Electric Current
Current is the flow of charge per unit time and is measured in amperes (A). Current is represented by the letter ‘I’.
–> 
As the formula above indicates, one amp of current is equal to the flow of one Coulomb of charge per one second. In other words, a wire carrying one amp of current moves one Coulomb of charge through the wire every second. When you are working with electricity, keep in mind that one amp is a large amount of current; less than 100 mA of current can kill you!
Voltage
Voltage is the difference in electric potential between two points and is measured in Volts (V). If you’ve taken physics, electric potential is similar to the concept of potential energy, except in this instance, electric potential is equal to the potential energy per unit charge. Voltage can be seen as the electric pressure, or driving force, that causes current to flow. You may also see voltage referred to as electromotive force.An important concept to understand when working with voltage and current is that there can be voltage without current flow, but there cannot be current flow without a voltage. For example, think of two people on opposite sides of a box. If both of them apply the same amount of force, the cart will not move. However, if one of them applies more force, the box will move. In both instances, a force (voltage) was applied to the cart (electrons), but only when there was a difference in force did we witness the cart move (current).
Conventional Current Flow
In the example above, the cart moves away from the person applying more force toward the person applying less force. Current and voltage interact in a similar manner in that current flows from higher voltages to lower voltages. In other words, current is said to flow from the positive terminal of a battery to the negative terminal. This is because current is described as the flow of positive charges. The electrons that actually carry the charge through the wire have a negative charge. Therefore, by definition, current flows in the opposite direction of the flow of electrons.Water Analogies
The challenge of learning the concepts of electricity is that electrons are hard to see and it’s hard for people to tell what is going on in a circuit. Analogies to water have been made to help people understand different concepts encountered in electrical engineering. Current, as you might have guessed, is compared to the flow of water while voltage is the difference in water pressure between two points. More water analogies will be made throughout the course to help you understand new concepts.This water analogy provides another example of how there can be voltage, but no current. Think of the build up of pressure behind a dam. The dam pushes back on the water, allowing no water to flow. This situation is similar to a battery. An ideal 12 V battery always has a potential difference between its terminals of 12 V, but no current flows until the battery is connected to a circuit.
Final Remark
Current is a through variable and voltage is an across variable. Current flows through circuits, voltage does not. Rather, voltage is the potential for current to flow. When referring to voltage, never say “the voltage through the resistor.” Instead, say “the voltage across the resistor” or “the voltage at a node.” This article was written and edited by Ryan Eatinger, Kansas State University (reatinge@ksu.edu), thanks for the donation.Basic Concepts
Basic Concepts:
Just Click The Above Link To Know the Basic Concepts.
These are the concepts in that site:
- Quantities
- Kirchoff's Laws
- Circuit Diagrams & Symbols
- Signals
- Introduction/Sines
- Signal Features & Measurements
- Signal Experiments
- Measurements
- Introduction
- Voltage
- Current (located in introductory lesson)
- Frequency
- Resistance
- Oscilloscopes
- Circuits
- Fourier Series
- Frequency Response
- Introduction
- Frequency Response Laboratories
By
Admin
Moki
GATE EXAM
Overall Paper Snapshot:
The candidates who appeared for GATE 2012 EE branch were in for a surprise, an unpleasant one though. There were no 'expected' questions which happen in an exam and the questions were designed to test not just the conceptual Knowledge of the candidates, but indepth understanding of the subject - coupled with extensive practice. The students who came out of the exam hall felt that paper was difficult than usual. An unusual thing about the EE GATE Paper this time, was in topics - Networks, Signals & Systems, Control Systems, Analog and Digital Electronics and Engineering Mathematics, ECE & EEE got the same questions. Thus in topics like Signals & Systems and Analog & Digital Electronics which are traditionally ECE subjects the questions, were unusually difficult from the perspective of EE student.
The General Aptitude section of GATE 2012 provided much need avenues to increase overall GATE Score of the candidate. Most of the questions were easy or of Moderate Level of difficulty – A candidate who has put in the required effort in practicing General Aptitude can score upto (10-12) marks in this section and this can go a long way in helping him meet the basic qualifying criteria. The candidates who found the level of difficulty of Engineering stream and Engineering Maths questions high would have got the much needed relief they were looking for in their quest to increase the GATE Score.
A candidate who can score (42-45) above can easily get a rank 1000’s below.
| Core Subjects | 1 Mark Qtns | 2 Mark Qtns |
| Electric Circuits and Fields | 5 | 6 |
| Signals and Systems | 1 | 1 |
| Electrical Machines | 1 | 3 |
| Power Systems | 3 | 2 |
| Control Systems | 1 | 5 |
| Electrical and Electronic Measurements | 3 | 1 |
| Analog and Digital Electronics | 4 | 4 |
| Power Electronics and Drives | 2 | 3 |
| Total Marks | 20 | 50 |
| Engineering Maths | 1 Mark Qtns | 2 Mark Qtns |
| Linear Algebra | 0 | 1 |
| Calculus | 0 | 2 |
| Differential equations | 1 | 0 |
| Complex variables | 2 | 0 |
| Probability and Statistics | 1 | 1 |
| Numerical Methods | 0 | 1 |
| Transform Theory | 1 | 0 |
| Total Marks | 5 | 10 |
| General Aptitude | 1 Mark Qtns | 2 Mark Qtns |
| Verbal Ability | 4 | 1 |
| Numerical Ability | 1 | 4 |
| Total Marks | 5 | 10 |
Core Subjects
Electric Circuits and Fields: (Networks for other branches) had highest weightage 17 Marks when compared with last year’s 11 marks. The questions were from fundamental topics; they will be easy for students who know the very basic concepts.
- The 1M question on average power, students usually study about the power dissipated in a resistor for DC current and to calculate the average value of current, for a given time dependent sinusoidal expression of current as two separate problems, but this time it was a combination of two such questions; hence moderately tough.
- There were 1 mark questions from Thevinin’s theorem and polyphase circuits which were asked directly from very basic concepts and were easy questions.
- Similarly capacitor and switch problem, one should know how ideal capacitor works with Resistor and with other ideal capacitor when connected through switch to answer this question, as both capacitors doesn’t respond for sudden changes in voltage.
- Other network problems like KVL and KCL analysis need some lengthy solutions, but by using simple short cuts one can solve them in lesser time.
- Difficult questions were seen from areas like maximum power transfer theorem and 2 port networks (Common data) for which no direct values were mentioned. To understand the question, a lot of thought process was required.
Signals and systems: Had same weightage 6 Marks when compared with last year. Questions were of analysis and application type. Usually this subject questions had a trend of framing question patterns as of previous question papers, but this time all questions were fresh, unique and analytical ones.
- Questions on Fourier transform, discrete convolution, system properties were difficult to answer.
- Question on ROC of z transform question is moderately difficult.
Electrical Machines: had very less weightage of 7 Marks when compared with last year’s 9 marks.
Electrical students always usually have high hopes on this subject, but this time it has gone down
- There was one memory recall type question which was very easy.
- Problems on DC motor and Induction motor were not much analytical; also similar questions have appeared in previous years. But would require few steps to get an answer.
- The question on transformer was lengthy and a lot of thought process would be required to understand the question.
Power systems: had less weightage of 7 Marks when compared with last year’s 11 marks.
Most of the questions were from familiar topics but either the questions were new or the solutions were a little bit complicated.
- The questions on economic power generation concepts (a previous year gate question pattern) and question on faults were moderate.
- The problems on bus admittance matrix, complex power demand and fault analysis were a bit difficult ones.
Control system: (common subject for all branches, EEE, EC, IN) was given more than expected weightage of 11 Marks when compared with last year’s 9 marks. But the level of difficulty is moderate for this subject.
- Linked answer question on compensator was a direct question to solve; one should have the knowledge of lead, lag compensator.
- Similarly a 2mark question from state variable analysis is a question pattern which was seen in past few year as well.
- Other questions in the area of steady state analysis are moderately difficult.
Electrical and Electronic Measurements: Had same weightage 5 Marks when compared with last year.
- There was one memory recall type question from AC bridges which was easy
- Other questions were from familiar and easier portion like PMMC, Measurement of power, Analog voltmeter; but were of moderate difficulty.
Analog and Digital Electronics: was given less weightage of 9 Marks when compared with last year’s 11 marks
- Questions can be also answered with simple basic concepts, V–I characteristics of diode question, one can get the answer simply by applying KVL (assume diode as dependent current source).
- Gain of BJT amplifier was difficult to answer; questions on flip-flops and Opamp Differentiator were moderately difficult.
- Question on state diagram was difficult to answer and question on number of input combinations was easy with application of little logic.
Power Electronics and Drives: Had same weightage 8 Marks when compared with last year.
- All the questions were from familiar topics and were of moderate difficulty.
- The common data question on 3 phase inverters but to understand the question and to think of a solution would be a little brainstorming.
| Mark Distribution based on Difficulty Level | ||||
| Subject | Easy | Moderate | Difficult | Total Marks |
| Electric Circuits and Fields | 7 | 10 | 17 | |
| Signals and Systems | 2 | 1 | 3 | |
| Electrical Machines | 1 | 6 | 7 | |
| Power Systems | 2 | 5 | 7 | |
| Control Systems | 8 | 3 | 11 | |
| Electrical and Electronic Measurements | 1 | 4 | 5 | |
| Analog and Digital Electronics | 10 | 2 | 12 | |
| Power Electronics and Drives | 8 | 8 | ||
| Total Marks | 1 | 42 | 27 | 70 |
Engineering Maths
- Engineering mathematics would be a key for good score; there were direct questions from Laplace transforms, linear algebra, but difficult questions from calculus, complex variables, probability & statistics. Comparatively, this year, Engineering mathematics was tougher than last few years.
| Mark Distribution based on Difficulty Level | ||||
| Topic | Easy | Moderate | Difficult | Total Marks |
| Linear Algebra | 2 | 2 | ||
| Calculus | 2 | 2 | 4 | |
| Differential equations | 1 | 1 | ||
| Complex variables | 1 | 1 | 2 | |
| Probability and Statistics | 2 | 1 | 3 | |
| Numerical Methods | 2 | 2 | ||
| Transform Theory | 1 | 1 | ||
| Total Marks | 5 | 5 | 5 | 15 |
General Aptitude
Questions from verbal ability were moderately difficult and questions from numerical ability were easy, except a different question from geometric probability which was difficult to answer. Data interpretation question were easy too.
| General Aptitude | Easy | Moderate | Difficult | Total Marks |
| Verbal Ability | 1 | 4 | 1 | 6 |
| Numerical Ability | 4 | 3 | 2 | 9 |
| Total Marks | 5 | 7 | 3 | 15 |
Though GATE 2012 paper included questions from easier topics hence the questions turned out to be complex and tougher. For solving them which requires thorough knowledge of basics and about how to use them in many different ways.
The Students, who have invested time and effort on Mathematics and G.A, have brighter chances of scoring well.
Overall GATE 2012 would have been easier for students who had a planned portion coverage focusing on basic fundamentals and who have the habit of reading standard author text books. For good score, it is not important to remember the lengthy formulae but need to know the basic concepts and techniques and methods to solve problems.
BY
ADMIN
Moki.
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