WHAT IS SYSTEM, BOUNDARY AND SURROUNDINGS

SYSTEM:
A System is a Finite quantity of matter
(or)
Prescribed Region of Space

BOUNDARY:
The actual or hypothetical envelope enclosing the system is called boundary. The boundary may fixed or may move. The boundary may be real or imaginary

SURROUNDINGS:
Everything outside the boundary is called surroundings

HOLDING CURRENT

HOLDING CURRENT
It is the maximum anode current, gate being open, at which SCR is turned off from ON conditions.

When Semi conductor Rectifier is in the conducting state, it cannot be turned OFF even if gate voltage is removed.  The only way to turn off or open the SCR is to reduce the supply voltage to almost zero at which point the internal transistor comes out of saturation and opens the SCR.  The anode current under this condition is very small (few mA) and is called Holding current.  If an SCR has a holding current of 5mA, it means that if anode current is made less than 5mA, then SCR will be turned off.

PEAK REVERSE VOLTAGE

PEAK REVERSE VOLTAGE
It is the maximum reverse voltage (cathode positive w.r.t anode) that can be applied to an SCR without conducting in the reverse direction.

Peak reverse voltage(PRV) is an important consideration while connecting an SCR in an a.c circuit. During the negative half of a.c supply, reverse voltage is applied across SCR.  If PRV is exceeded, there may be avalanche breakdown and the SCR will be damaged if the external circuit does not limit the current.  

BREAKOVER VOLTAGE

BREAKOVER VOLTAGE
It is the minimum forward voltage, gate being open, at which  Semi Conductor Rectiver(SCR) starts conducting heavily i.e turned on

if the breakover voltage of an SCR is 220V, it means that it can block a forward voltage as long as the supply voltage is less than 220V.  If the supply voltage is more than this value, the SCR will be turned on.  In practice SCR is operated with supply voltage less than breakover voltage and it is then turned on by means of a small voltage applied to the gate.

SILICON CONTROLLED RECTIFIER (SCR)

SILICON CONTROLLED RECTIFIER (SCR)
is a semiconductor device that acts as a true electronic switch.  It can change alternating current into direct current and at the same time can control the amount of power fed to the load.  SCR combines the features of a rectifier and a transistor.

MERITS AND DEMERITS OF MULTIMETER

Multimeter is widely used for manufacturing and servicing of electrnoics equipment.  It has its own merits and demerits.

Merits:
It has a single meter which performs several measuring functions
it can make measurements with reasonable accuracy

Demerits:
It cannot make precise and accurate measurements due to the loading effect
Technical skill is required to handle it.

WHAT IS MULTIMETER SENSITIVITY

The resistance offered per volt of full scale deflection by the multimeter is known as multimeter sensitivity. it indicates the internal resistance of the multimeter.  If the sensitivity of a multimeter is high, it means that it has high internal resistance. when such a meter is connected in the circuit to read voltage, it will draw a very small current.  if the sensitivity is low, it would cause serious error in voltage measurement.

WHAT IS MULTIMETER

Multimeter is an electronic instrument used for measuring resistances, current and voltages. it can be used for measuring D.C aswell as A.C voltages and currents.

WHAT ARE THE APPLICATIONS OF MULTIMETER

A multimeter is used for
1)checking the circuit continuity.
2)measuring d.c. voltages across various resistors in electronic circuits.
3)measuring d.c current flowing through the cathode, plate, screen and other vacuum tube circuits
4)measuring a.c. voltages across power supply transformers
5)ascertaining whether or not open or short circuit exists in the circuit.

APPLICATIONS OF VTVM

A VTVM is used for 
1) D.C Voltage measurements:
A VTVM can accurately measure the D.C voltages in an electronic circuits.  

2)D.C Current Measurements:
VTVM does not incorporate a current scale, however current values can be found indirectly.

3)A.C voltage Measurements:
For measuring A.C voltage, a rectifier is used in conjunction with a VTVM.

4)Resistance measurements:
VTVM has ability to measure resistance upto 100 M ohms

VACUUM TUBE VOLTMETER (VTVM)

VTVM is extensively used for measuring both A.C and D.C voltages.  The Vacuum tube voltmeter has high internal resistance (>10 M ohms) and draws extremely small current. The loading effect is very small. A VTVM measures the exact voltage even across a high resistance.  A vacuum tube voltmeter consists of voltmeter and electron tubes.

WHAT IS DIAC

A Diac is a two terminal, three layer bidirectional device which can be switched from its OFF state to ON state for either polarity of applied voltage.  The diac can be constructed in either npn or pnp form.

MERITS AND DEMERITS OF VTVM (VACUUM TUBE VOLTMETER)

A VTVM is an extremely important electronic equipment and is widely used for making different measurements in electronic circuits.

Merits:
* A VTVM draws extremely small current from the measuring circuit.  therefore it gives accurate readings.

* VTVM uses triodes, the voltage to be measured is amplified.  This permits the use of less sensitive meter.

*There is little effect of temperature variations

*It has wide frequency response

Demerits:
*Accurate readings can be obtained only for sine waves.

*It cannot make current measurements directly.

WHAT IS VAT

VAT is a tax levied and collected on the value added to any goods each time they change hand

WHAT ARE THE FEATURES OF VAT

1) VAT is a tax levied and collected on the value added to any goods each time they change hand
2)The transaction shall a sale
3)Sale shall be made by a registered dealer
4)VAT shall be payable at every point of sale
5)Input tax credit shall be admissible on the input tax paid in respect of previous purchases
6)Output tax shall be collected on every sale
7)VAT is applicable for intrastate trade
8)VAT ensures with uniform rates and procedures. It ensures transparency and reduction in consumer prices.

WHAT IS 80C TAX DEDUCTION

General deduction for investment in PPF, PF, LIC,ULIP, Stamp duty on house, Fixed deposits for 5 years, bonds, Contribution to statutory PF or Recognised PF, For LIC policy must be in self or spouse's or any child's name.  Premium paid towards LIC policy not exceeding 20% of the total sum assured.  Repayment of housing loan principal towards self occupied residential property. Payment of tuition fees towards any two children of the assesses.

WHAT IS TAX DEDUCTION AT SOURCE

TDS means Tax Deduction at Source
In simple terms, TDS is the tax getting deducted from the person receiving the amount (Employee/Deductee) by the person paying such amount (Employer/Deductor) 

Empoyee's income Tax is deducted at source means his tax on income is deducted by the employer (who is paying salary), employer pays the same to the income tax department.

WHAT IS CIN

Challan Identificaiton Number, is stamped on the acknowledgement receipt to uniquely identify the tax payment.  CIN has to be quoted in the return of income as a proof of payment.

WHAT IS CHALLAN IDENTIFICATION NUMBER

Challan Identificaiton Number, is stamped on the acknowledgement receipt to uniquely identify the tax payment.  CIN has to be quoted in the return of income as a proof of payment.

PROCEDURE FOR PAYMENT OF DIRECT TAXES AT BANKS

If you are paying taxes in cash at any designated bank branch or by cheque at the bank branch where you have a bank account, the bank will accept your cash/ cheque and will immediately stamp the counterfoil of the challan with a rubber stamp containing the CIN.  If however, you are paying taxes by cheque/draft at a bank branch other than where you have a bank account, the collecting bank branch will accept your cheque/draft and issue you a paper token in acknowledgement.  When you present this token after encashment of the cheque, the bank will hand over the acknowledgement counterfoil duly stamped with the CIN.

WHAT IS PAN

PAN means Permanent Account Number, is a ten digit alphanumeric number issued by the income tax department.

WHAT IS TAN

TAN Means  Tax Deduction Account Number
TAN is a unique identification number for person deducting the tax. The person who is liable to deduct the tax should obtain a TAN before deducting such Tax.

DIFFERENCE BEETWEEN BUSINESS AND PROFESSION

Business, simply means any trade, commerce,manufacturing activity, or any adventure or concern in the nature of trade, commerce and manufacture.

Profession,  a job requiring some thought, skill and special knowledge like that of  C.A, Lawyer, Engineer, Doctor, Architect etc.,

WHAT ARE CORPORATES

Companies or Branches of companies registered under companies Act 1956.

WHO IS DEDUCTOR

Deductor is a person/company who is liable to deduct the Tax at source, from the payment being made to the party, Deductor is also termed as Employer.

WHAT IS TDS

TDS means Tax Deduction at Source
In simple terms, TDS is the tax getting deducted from the person receiving the amount (Employee/Deductee) by the person paying such amount (Employer/Deductor) 

Empoyee's income Tax is deducted at source means his tax on income is deducted by the employer (who is paying salary), employer pays the same to the income tax department.

WHAT ARE LOCAL TAXES

TAXES LEVIED BY MUNICIPAL/ LOCAL TAXES

Property/Building tax levied by local bodies.
Agriculture income tax levied by State governments on income from plantations.

WHAT ARE INDIRECT TAXES

Excise Duty, Customs Duty, Service Tax, Securities Transaction Tax

WHAT ARE DIRECT TAXES

Tax on Corporate income, Capital gains tax, income tax, Tax incentives.

ON WHICH ITEMS OR MATERIAL STATE GOVERNMENT COLLECT TAX

State Government levies taxes on Value Added Tax (VAT), stamp duty, State Excise, land revenue and tax on professions

ON WHICH ITEMS OR MATERIAL CENTRAL GOVERNMENT COLLECT TAX

Central Government levies taxes on income ( except income on agricultural income, which state government can levy), custom duties, central excise and service tax.

WHAT IS CATHODE RAY OSCILLOSCOPE

CATHODE RAY OSCILLOSCOPE:
Cathode ray Oscilloscope is an electronic device which is capable of giving a visual indication of a signal wave form. It is widely used for troubleshooting radio and television receivers.

WHAT IS CATHODE RAY TUBE

CATHODE RAY TUBE:
Cathode Ray Tube is the heart of the oscilloscope.  It is a vacuum tube of special geometrical shape and converts an electrical signal into visual one.  A cathode ray tube makes available plenty of electrons.  These electrons are accelerated to high velocity and are brought to focus on a fluorescent screen.  The electron beam produces a spot of light wherever it strikes.

WHAT IS MICRO ELECTRONICS

MICRO ELECTRIONICS:
Micro Electronics is the branch of electronics engineering which deals with micro circuits.  A micro circuit is simply a miniature assembly of electronic components. e.g Integrated circuit.

WHAT IS AN INTEGRATED CIRCUIT

INTEGRATED CIRCUIT:
An Integrated Circuit is one in which circuit components such as transistors, diodes, resistors, capacitors etc. are automatically part of a small semiconductor chip.

An integrated circuit consists of a number of circuit components ( e.g transistors, diodes, resistors etc) and their inter connections in a single small package to perform a complete electronic function.

WHAT IS MONOLITHIC IC

MONOLITHIC IC:
Monilithic IC is one in which all components and their inter connections are formed on a single thin wafer called substrate.

WHAT ARE HYBRID PARAMETERS

HYBRID PARAMETERS:
Every Linear Circuit having input and output terminals can be analysed by four parameters (one measured in ohm, one in mho and two dimensionless) called hybrid parameters

Hybrid means "mixed".  Since these parameters have mixed dimensions, they are called hybrid parameters.

WHAT IS DIGITAL SIGNAL

Digital Signal:
A Signal (Voltage or Current) that can have only two discrete values is called a digital signal.  A square wave is a digital signal because this signal has only two values. +5V and OV and no other value.

WHAT IS ANALOG SIGNAL

Analog Signal:
A continuously varying signal (Voltage or Current) is called an analog signal.  An alternating voltage varying sinusoidally is an analog signal.

WHAT IS DIGITAL CIRCUIT

Digital Circuit:
An electronic circuit that handles only a digital signal is called a digital circuit.

WHAT ARE LOGIC GATES

LOGIC gates:
A digital circuit with one or more input signals but only one output signal is called a logic gate. Logic gate is a switching circuit.

WHAT ARE THREE BASIC LOGIC GATES

Three Basic Logic Gates:
A Logic gate is a circuit that has one or more input signals but only one output signal.  All logic gates can be analysed by constructing a truth table.  A truth table lists all input possibilities and the corresponding output for each input.

The three basic logic gates that make up all digital circuits are 
1) OR gate  2)  AND gate  3) NOT gate  

WHAT IS OR GATE

OR gate:
OR gate has two or more inputs but only one output. The output y of an OR gate is low when all the inputs are low. The output y of an OR gate is High if any or all the inputs are High.

WHAT IS NOT GATE OR INVERTER

NOT gate:
NOT gate or inverter  has only one input and one output, where the output is opposite of the input. The Not gate is also called "inverter" because it inverts the input.

WHAT IS AND GATE

AND gate:
AND gate is a logic gate that has two or more inputs but only one output.  The output y of AND gate is High when all inputs are high.
The output y of AND gate is low if any or all inputs are low. it is also called "all or nothing gate".  Output will be high when both the inputs are high.

NOT GATE FROM NAND GATE

NOT gate from NAND gate:

When two inputs of NAND gate are joined together so that it has one input, the resulting circuit is NOT gate.

NAND Gate is a Universal Gate

NAND gate is a universal gate because its repeated use can produce other logic gates.

WHAT IS NOR GATE

NOR gate:
It is a combination of OR gate and NOT gate.  Output of OR gate is connected to the input of a NOT gate.

WHAT IS NAND GATE

NAND gate:
It is a combination of AND gate and NOT gate.  Output of AND gate is connected to the input of a NOT gate.

WHAT IS DEMORGAN'S THEOREMS

Demorgan's theorems are used in simplifying expressions which includes a product or sum of variables is inverted

Demorgan's First Theorem:

When the OR sum of two variables is inverted, this is equal to inverting each variable individually and then ANDing these inverted variables.

________          ____   _____

A + B    =     A    .  B

Demorgan's Second Theorem:

When the AND product of two variables is inverted, this is equal to inverting each variable individually  and the ORing them.

______    ___       ___

(A . B ) =   A      +  B

WHAT IS ENCODER AND DECODER

Encoder

The Circuit that converts decimal form to digital (binary) form is called Encoder

Decoder

The circuit that converts digital form to decimal form is called decoder

SHORT CUT KEY TO MAXIMISE A WINDOW

Short cut key to maximise a window

press  "Windows Key + Up Arrow Key"

SHORT CUT KEY TO MINIMISE A WINDOW

Short cut key to minimise window

press  "windows key + M"

SHORT CUT KEY TO OPEN WINDOWS SEARCH

Short cut to open windows search

press  " windows key + F"

SHORT CUT TO OPEN MY COMPUTER

Short cut to open My Computer:

press  "windows key + E"

SHORT CUT TO MINIMISE ALL ALREADY OPENED WINDOWS AT A TIME IN YOUR COMPUTER

Short cut to minimise all already opened windows at a time:

press   "windows key  +  D"

SHORT CUT KEY TO KNOW THE IP ADDRESS OF COMPUTER

Short cut to know IP Address of computer:

open  "Run"    and    type  "CMD"

and  type  "ipconfig" and  press "Enter"

SHORT CUT TO DECREASE FONT SIZE IN MS-WORD

Short cut key to decrease font size in MS-Word

open "MS-Word" document

and  press   "  Ctrl  +  Shift  +  <  "

SHORT CUT KEY TO INCREASE FONT SIZE IN MS-WORD

Short cut key to increase Font Size in MS-Word

open "MS-Word" document

and press  " Ctrl  + shift + > "

SHORT CUT KEY FOR PRINT PREVIEW IN MS-WORD

Short cut key for print preview

open  "MS-Word" document

and  press  "Ctrl+F2"

SHORT CUT KEY TO OPEN C DRIVE IN YOUR COMPUTER

Short cut key to open C: Drive

Open "Run"

and type   "C:"

and press "Enter"

SHORT CUT KEY TO OPEN "PAINT" IN YOUR COMPUTER

Short cut key to open  "Paint software" 

open  "Run"

and  type  "mspaint"

and press "Enter"

SHORT CUT KEY TO OPEN "RUN" IN YOUR COMPUTER

Short cut key to open "RUN"

Press  "Windows Key"  (bottom left side in the key board)

and  Press  "R"

(short cut key:   windows key+R)

SHORT CUT KEY TO OPEN MS WORD

Short cut key to open MS-Word in your computer:

open  "Run" 

and  type   "winword"  

and press "Enter"

DIFFERENCE BETWEEN FREEZE AND TURN LAYERS OFF IN AUTO CAD

From outside you cannot identify the difference between
FREEZE and TURN LAYERS OFF.  If you Freeze a layer 
then its contents are not displayed.  And Similarly if you
turn off layer, its contents are not displayed.  Only 
difference between these FREEZE and TURN LAYERS OFF
is in display Memory.  When a layer is frozen the information
required to display it on screen is not loaded onto your
graphics card memory.  And when a layer is turned off,
all the information required to display the entities on that 
layer is loaded into your Graphic's Card's Memory.

if you turn off a layer, you get slower panning and zooming
on large/ complex drawings.

If you Freeze a layer, you get faster panning and zooming.

HOW TO CALCULATE KVA POWER REQUIREMENTS OF A GENERATOR

Procedure for  calculating the power (KVA) requirements of a Generator.  

example:  
A house has  10 tube lights, 5 Bulbs, 6 Ceiling Fans,  1 TV, 2 Personal Computers,  1 Laser Printer, 1 Iron Box etc.,

* write down  watts or Volts and Amps from each equipment
printed on its cover or in the manual. 

1 Tube Light = 40 watts, 10 Tube Lights = 10 X 40=400Watts
1 Bulb          = 60 watts,   5 Bulbs = 5 x 60 = 300 Watts
1 CeilingFan = 80 Watts,  6 C.Fans=6 x 80 =440 Watts
1 TV             = 135Watts,  
1 Personal Computer=275 Watts,  2 PC = 2 x 275=550Watts
1 Laser Printer = 375 Watts
1 Iron Box= 1000 Watts

*  Add all the Wattage
   400+ 300+440+135+550+375+1000=3200 Watts

   Total Watts = 3200

*  By Dividing with 1000 we get Kilo Watts
   3200/1000  =  3.2 Kilo Watts or KW

* Take Power Factor is 0.8 ( it depends upon the system
   Efficiency)

* By Dividing  3.2 KW by 0.8  we get the Required KVA

  3.2 / 0.8  = 4 KVA.

 Now select the Generator that is having  4 KVA
 Power generating capacity.

ANGULAR VELOCITY

Angular Velocity is the rate of change of Angular Displacement.

Angular Velocity is a Vector Quantity

SI unit of Angular Velocity is Radians/sec

The Direction of Angular Velocity vector is perpendicular to the plane of rotation.

                                      Angular Displacement

Angular Velocity  =      -----------------------------------------

                                                 time

WHAT IS POWER FACTOR

Power Factor is a measure of how effectively the current is being converted into useful work output. A load with a power factor 1.0 represents most efficient loading of suply and a 
load with power factor 0.5 represents poor supply or much higher losses in the supply system.

or

Power Factor is the ratio between KW (Kilo-Watt) and the KVA (Kilo-volt-amp).  where KW is the actual load power and
KVA is the apparent load power.

DIFFERENCE BETWEEN KW AND KVA

Power Factor is the only difference between KW and KVA.

Power Factor is generally is an approximation. Unless it is

represented by the manufacturer.  The value of KVA
is generally larger than the KW.

ex:  consider power factor  is 0.95  

KW(kilo Watt) = Power Factor * KVA

                      = 0.95 * KVA 

or 

KVA( Kilo Volt Amp) = KW (Kilo Watt) / Power Factor

                               =  KW (Kilo Watt) / 0.95

USE OF ACTIVE VOICE AND PASSIVE VOICE

Though, In general Active voice is preferred, most
grammarians agree that the passive voice should be used when the receiver of the action is more important that the doer.

Eg: "The city was devastated by a tsunami"
                   (passive voice)
this sentence is better rather than

"A tsunami devastated the city"  (active voice)

so in this case passive voice is preferred to active voice.
 

TRANSCONDUCTANCE

The ratio of small change in plate current to the small change in grid voltage at constant plate voltage is known as transconductance or mutual conductance.

Transconductance or mutual conductance indicates the effectiveness of grid potential in changing the plate current.

AMPLIFICATION FACTOR OF VACUUM TUBE

The ratio of small change in plate voltage to a small change in grid voltage of a triode at constant plate current is known as amplification factor.

The amplification factor of a tube is a measure of its effectiveness of grid voltage relative to the plate voltage  in controlling the plate current.

VACUUM TUBE

An electronic device  in which the flow of electrons is through a vacuum is known as vacuum tube.

A vacuum tube usually contains a cathode which is the electron emitter, an anode (plate) which is the electron collector and one or more electrodes (grids) for controlling the flow of electrons between cathode and anode.  These electrodes are housed in a highly evacuated glass envelope. The ability of vacuum tubes to conduct current in vaccum enables them to perform different functions.

SECONDARY EMISSION

Electron emission from a metallic surface by the bombardment of high speed electrons or other particles is known as secondary emission.

In this method, a high velocity beam of electrons strikes the metal surface and causes the free electrons of the metal to be knocked out from the surface.

FIELD EMISSION

The process of electron emission by the application of strong electric field at the surface of a metal is known as field emission

In this method, a strong electric field is applied at the metal surface which pulls the free electrons out of metal because of attraction of positive field.  The stronger the electric field, the greater is the electron emission.

PHOTO ELECTRIC EMISSION

Electron emission from a metallic surface by the application of light is known as photo electric emission

In this method, the energy of light falling upon the metal surface is transferred to the free electrons within the metal to enable them to leave the surface.  The greater the intensity of light beam falling on the metal surface, the greater is the photo electric emission.

THERMIONIC EMISSION

The process of electron emission from a metal surface by supplying thermal energy to it is known as thermionic emission.

In this method, the metal is heated to sufficient temperature (about 2500 deg c) to enable the free electrons to leave the metal surface.  The number of electrons emitted depends upon the temperature.  The higher the temperature, the greater is the emission of electrons. this type of emission is employed in vacuum tubes.

TYPES OF ELECTRON EMISSION

The electron emission from the surface of a metal is possible only if sufficient additional energy is supplied from some external source. This external energy may come from a variety of sources such as heat energy, energy stored in electric field, light energy etc.,

there are four principal methods of obtaining electron emission from the surface of a metal

1) Thermionic emission: 
In this method the metal is heated to sufficient temperature (about 2500 deg C) to enable the free electrons to the leave the metal surface.  The number of electrons emitted depends upon the temperature.  The higher the temperature, the greater is the emission of electrons.  This type of emission is employed in vacuum tubes.

2)Field emission:
In this method, a strong electric field (high positive voltage) is applied at the metal surface which pulls the free electrons out of metal because of the attraction of positive field.  The stronger the electric field, the greater is the electron emission.

3)Photo-electric emission:
In this method, the energy of light falling upon the metal surface is transferred to the free electrons within the metal to enable them to leave the surface.
The greater the intensity of light beam falling on the metal surface, the greater is the photo electric emission.

4)Secondary emission:
In this method, a high velocity beam of electrons strikes the metal surface and causes the free electrons of the metal to be knocked out from the surface.

WORK FUNCTION OF A METAL

The amount of additional energy required to emit an electron from a metallic surface is known as Work function of that metal

ELECTRON EMISSION

The liberation of electrons from the surface of a substance is known as electron emission.

NORTON'S THEOREM

Any network having two terminals A and B can be replaced by a current source of output Ia in parallel with a resistance Ra.

i) The output Ia of the current source is equal to the current that would flow through AB when A and B are short circuited.

ii) The resistance Ra is the resistance of the network measured between terminals A and B with load (Rc) removed and sources of e.m.f replaced by their internal resistances, if any

Norton's theorem is converse of thevenin's theorem.

SEMI CONDUCTOR

A Semi Conductor is a substance which has very few free electrons at room temperature. under the influence of potential difference, a semi conductor practically conducts no current.

INSULATOR

An insulator is a substance which has practically no free electrons at ordinary temperature.  Therefore, an insulator does not conduct current under the influence of potential difference.

CONDUCTOR

Conductor is a substance which has a large number of free electrons.  When the potential difference is applied across a conductor, the free electrons move towards the positive terminal of supply, constituting electric current.

ELECTRON

An electron is a negatively charged particle having negligible mass. mass of an electron is very small as compared to its charge. it is very mobile and is greatly influenced by electric or magnetic fields.

ATOMIC WEIGHT

The sum of protons and neutrons constitutes the entire weight of an atom and is called atomic weight

NUCLEUS

It is the central part of an atom and contains protons and neutrons.  A proton is a positively charged particle, while the neutron has the same mass as the proton, but has no charge.  Therefore, the nucleus of an atom is positively charged.

AMPLIFICATION

The process of raising the strength of a weak signal is known as amplification. Electronic devices that can accomplish the job of amplification are known as amplifiers.

RECTIFICATION

The conversion of a.c (alternating current) into d.c (direct current) is known as rectification.  Electronic devices can convert a.c power into d.c power with very high frequency.  This d.c supply can be used for charging batteries,electro plating and various other applications.

POWER DISSIPATION CAPABILITY

The ability of a power transistor to dissipate heat is known as Power dissipation capability

TRANSISTOR AUDIO POWER AMPLIFIER

A Transistor amplifier which raises the power level of the signals that have audio frequency range is known as transistor audio power amplifier

DISTORTION

The change of output wave shape from the input wave shape of an amplifier is known as Distortion

COLLECTOR EFFICIENCY

The ratio of a.c output power to the zero signal power (d.c. power) supplied by the battery of a power amplifier is known as collector efficiency

THERMAL RUNAWAY

The unstable condition where, owing to rise in temperature, the collector current rises and continues to increase is known as thermal runaway

HEAT SINK

The metal sheet that serves to dissipate the additional heat from the power transistor is known as heat sink

TRANSISTOR BIASING

The Basic function of transistor is to do amplification.
The weak signal is given to the base of the transistor and amplified signal is obtained at the collector.  One important requirement during amplification is that there should be no change in the shape of signal.

This increase in magnitude of signal without change in the shape of signal is known as faithful amplification.
In order to achieve this, base-emitter junction of the transistor remains forward biased and collector-base junction remains reversed biased during all parts of the signal. This is known as transistor biasing.

"Proper flow of zero signal collector current and the maintenance of proper collector-emitter voltage during the passage of signal is known as transistor biasing"

A transistor amplifier must satisfy three basic conditions.

1) proper zero signal collector current
2) proper base emitter voltage at any instant
3) proper collector-emitter voltage at any instant.

EMITTER, COLLECTOR AND BASE OF A TRANSISTOR

A transistor has three sections, The section on one side is Emitter, and the section on the opposite side is the collector.  The middle section is called the base.

Emitter:
The section on one side that supplies charge carriers (electrons) is called the emitter. The emitter is always forward biased with respect to base.

Collector:
The section on the other side that collects the charges is called the collector. the collector is always reverse biased.  Its function is to remove charges from its junction with base.

Base:
The middle section which forms two pn junctions between the emitter and collector is called the base.
The base emitter junction is forward biased and the base-collector junction is reverse biased.

TRASISTOR

When a third doped element is added to a crystal diode in such a way that two pin junctions are formed, the resulting device is known as transistor.

A transistor consists of two pn junctions formed by
sandwiching either p type or n type semiconductor between a pair of opposite types.

there are two types of transistors

1) n-p-n transistor
2) p-n-p transistor


A n-p-n transistor is composed of two n-type semiconductors separated by a thin section of p-type semiconductor. 

A p-n-p transistor is composed of  two p-type semiconductors separated by a thin section of n-type semi conductor.

In any transistor, there are two pn junctions.  therefore a transistor may be regarded as a combination of two diodes connected back to back.

There are three terminals in a transistor  1) Emitter
2)Collector    3) Base

WHAT IS A COLUMN, SHORT COLUMN, LONG COLUMN

Column:
A column is a vertical compression member.  A column is subjected to axial compressive loads.

Short Column:
When the ratio of effective length to the least lateral dimensions of the column is less than 12, then it is
called a short column.

(or)
When the ratio of effective length to the least radius of gyration is less than 45, then it is called a short column

Long Column:
When the ratio of effective length to the least radius of gyration is greater than 45, then it is called a long column.

A long column is subjected to bending moment in addition to direct compressive stress.

The load carrying capacity of a long column is less than a short column

The load carrying capacity of a long column depends upon slenderness ratio (slenderness ratio increases then the capacity of the column decreases)

WHAT IS FOREX, FOREIGN EXCHANGE MARKET

Foreign Exchange, simply called Forex
also called as currency market.  Simultaneous purchase and sale of one country's currency to
another country's currency.  in simple terms
buying of one currency and selling another currency at the same time.

The world currencies do not have a fixed exchange rates and they are always fluctuating.

Forex trading allows an investor to participate in profitable fluctuations of world currencies.