Coulomb's law of electrostatic (in scallar form)

 Coulomb's law of electrostatic (Scalar form) 

We know the like charges reple each other and unlike charges attract each other. The force between two charges is given by coulomb's law. This is an electric analogue of newton's law of gravity. 

Statement:

It states that electrostatic force of attraction or repulsion between two charged bodies is directly proportional to the product of their charges and various inversely as the square of the distance between the two bodies. 

The force is also depends on the nature of the intervening medium and it act along the line joining two charges. 

Suppose two point charɡes q₁ and q₂ are situated at a distance r from each other in same medium. The maɡnitude of the electrostatic force F which one exerts on the other will be ɡiven by

    F ∝ q₁q₂  and  F ∝ 1/r² (inverse square law)

Combininɡ,

             F ∝ q₁q₂/r²    or    F ∝ β q₁q₂/r²

Where β is a constant of proportionality. In fact, the value of β depends on the nature of the medium in which the two charges are situated. It also depends on the units in which the quantities F, q₁, q₂ and r are measured. 

Coulomb's law is strictly true for point charges only. 

Units:

1) In C.G.S. (e.s.u.) system:

In C.G.S. (e.s.u.) system, β = 1/K

Where K = dielectric constant of the medium. 

Mathematical form of Coulomb's law in this system is -    

             1    q₁q₂      

     F=  —    ——             ( for any medium) 

           K        r²

In free space,       K = 1

         F = q₁q₂/r²             (for free space) 

2) In S.I. units:

In S.I. units,  β = 1/4πɛ = 1/4πɛ₀ɛr

Where ɛ₀ and ɛr are the absolute permittivity and relative permittivity, respectively. 

Mathematically, Coulomb's law can be written as :

     F = 1/4πɛ₀ɛr × q₁q₂ /r²   (for any medium) 

For free space, ɛr = 1

∴       F = 1/4πɛ₀ × q₁q₂ /r²    (for free space) 

 Some observations of coulomb's law:

1. Coulomb obtain this law to experiment so, it is basically and experiment law. 
2. The law is strictly applicable in case of a point charges. If a charged body possesses negligible dimensions the charge is said to be a point one. 
3. Each charges extract the some force on each other. 
4. Coulomb's force between two charges matually interaction. 
5. Coulomb's interaction is not affected by the present of other charges in the neibourhood. 
6. It is applicable only the charges at rest. While dealing with force between charges in motion, the expression has to be modified. 
7. Coulomb's law of electrostatic is not valid if r is less than 10^-15m.
8. Coulomb's force is attractive for dissimilar charges and while it is repulsive for similar charges. 
9. The magnitude of the force depend upon the magnitude of the charges separation between them and also depend upon the nature of the medium in between them. 
10. Coulomb's force is a central force that is the force acting alone the link joining the two charges. 
11. Coulomb's force is conservative nature i.e the work done by the electrostatic force over a closed path is zero and it independ of the path follow. 

Electrification - "Electric charges"

Electric charges:

 Historical review of Electrostatics

Science of electrostatic has its origin dated back, about 2600 years. For a long time, the phenomenon remained unexplained. With the development of science, various arguments were put forward to explain it. 

1. The first observation is credited to a Greek philosopher Thales of Miletus (640-540 B.C.) who observed that is 'amber' (hardened sap of a kind of pine tree, a yellow resinous substance found on the shores of Baltic sea) is rubbed with silk or flannel, it acquires the property of attracting straw towards itself. No explanation to this phenomenon could be given at that stage. 
2. About 2000 years after this an English Physicist William Gilbert observed that there were a number of other substances, apart from 'amber' which acquired this property when rubbed. He named this property as 'electric attraction'. The word electric was ascribed to this characteristics because the amber was known as 'electron'. 
3. In 1671, Otto von Guericke discovered the property of electric repulsion when he found that some features moved away from a charged body if allowed to touch and separate. 

Electrification - "Electric Charges"

Science of electrostatics, has its origin dated back to 600 B.C. of course, the name electrostatics was given to it much later. The discovery is credited to a Greek Philosopher Thales of Miletus (600 B.C.). He observed that if amber (a yellow resinous substance found on the shores of Baltic sea) is rubbed with a woollen cloth, it acquires some special properties of attracting small pieces of paper, light features, dust etc. towards it. Same phenomenon is observed in case a glass rod is rubbed with a silk cloth. Even if we test our comb after combing our hair, it is found to show this phenomenon. The amber, the glass rod or the comb is said to have acquired electricity on itself. The word 'electricity' is derived from 'electrum' which is a Greek name of amber. 

These substances tend to show abnormal behaviour due to reason that they have developed some charges upon themselves or in other words they have been electrified. A charge cannot be termed as something physical, i.e. something having shape, size or volume. 

A charge is a fundamental characteristics property of the elementary particle of the mental which is explain certain force of interaction and some type of interaction energy. 

• The word electricity is derived from electrum. 
• Electric charge is scaller quantity. 

William gillbert who did primity ward on electrification. He observed that there are two types of electrification is possible. 

1. One type of electrification is acquired by umber rubbed with wollen clothe. This type of electrification is named as resinous. 
2. Second type of electrification is acquired by a glass rod rubbed with silk. This type of electrification is named as vitreous. 

Latin american scientist Benjamin Franklin named +ve and -ve charge. 

1. Type of charge acquired by a glass rod when rubbed with silk is called +ve charge. 
2. Type of charge acquired by umber when rubbed with woollen cloth is called -ve charge. 

For production of electric charges we need a predestined pair of substances and these have to be rubbed together. As a result of electrification, one substance (of the pair) acquires a positive charge while the other acquires a negative one. Following table gives a number of such pairs along with the nature of charges developed upon them. 

Table:

Sl no.	Pair	Positively charged	Negatively charged
1.	Glass, Silk	Glass	Silk
2.	Cat skin, Ebonite	Cat skin	Ebonite
3.	Flannel, Ebonite	Flannel	Ebonite
4.	Woollen cloth, Amber	Woollen cloth	Amber
5.	Woollen cloth, Rubber	Woollen cloth	Rubber
6.	Woollen cloth, Plastic	Woollen cloth	Plastic
7.	Dry hair, Comb (Plastic)	Dry hair	Comb

Like charges repel and unlike charges attract each other - "Basic law of Electrostatic "

It can be proved that like charges repel each other and unlike charges attract each other. 

Consider two light pith ball pendulums A and B lined with a thin metallic foil and suspended with cotton threads close to each other. 

1) Rub two amber pieces with woollen clothes and touch them with the pendulum. On removing amber it is found that two pendulums get repelled away from each other [Fig. (i)]. This is due to the reason that both of them acquired similar charges. Same observation will be obtained when repeated with glass rods rubbed with silk. 

Electrostatic interaction. 

2) Rub amber with woollen cloth and glass with silk. Touch amber with pendulum A and glass with pendulum B. It will be observed that the two pendulums A and B move towards each other indicating that they attract each other [Fig. (ii)]. This is due to the reason that they had been given opposite type of charges. 

These two experiments also indicate that there are two types of charges produced as a result of rubbing one substance with another. 

Existence of only two types of charges

It can be proved that there is existence of only two types of charges 'positive and negative'. Let the glass, already rubbed with silk, be denoted as a body A while amber, rubbed with woollen cloth, be denoted as a body B. Let 'C' be any other charged body in this universe. Bring 'C' near A and B turn by turn, it will be observed that if C is attracted by A, it will be repelled by B and vice-versa. We cannot find any charged body which is attracted or repelled by A and B simultaneously. If a number of charged bodies are all repelled by A, these bodies are bound to repel each other also. This indicates that the charges on all these bodies belong to one category only and is similar to the charge on A. If a number of charged bodies are repelled by B, they are bound to repel each other also, indicating that they possess charges of one category and that is similar in nature to the charge on B. 

Hence, there is a possibility of only two types of charges, one produced on glass rod when rubbed with silk (called positive) and second on amber when rubbed with woollen cloth (called negative). 

JAVA

Java:

 Java is a OOP originally developed by sun microsystems which was initieted by Jems Gosling and released in 1995. It is owned by oracle and more than 3 billion devices run java. 

Java is a High Level, Object-Oriented, Secure Programming Language, High Performance, Robust, Platform Independent, Multi thread, Portable Programming Language. It own Java Runtime Environment (JRE) and Application Programming Interface (API). 

Use of Java:

Java is used for -

1. Mobile applications (specially android apps) 
2. Desktop applications
3. Web applications
4. Web server and application servers
5. Games
6. Data base connection. 

Advantage of Java:

1. Java works on different platforms (Ma-windows, Mac, Linux, etc.) 
2. It is one of the most popular programming language in the world. 
3. Simple and easy to learn. 
4. Open source and free. 
5. It is a fast, secure, powerful programming language. 
6. Java is a OOP which gives a clear structure to programs and allow code to be reused, lowering development cost. 
7. Huge community support. 
8. As Java is close to C and C++, it makes easy for programmers to switch to Java or vice versa. 

Features of Java:

1) Simple. Java is easy to learn and it's syntax is quite simple, clean and easy to understand. The confusing and ambiguous concept of C++ are either left out in Java or they have been re-implimented in a cleaner way. 

     Example- Pointers and operator overloading are not there in Java but we're an important part of C++.

2) Object oriented. In Java, everything is an object which has some data and behaviour. Java can be easily extended as it is based on object model. 

Some basic concept of OOP's are-

(i) Object

(ii) Class

(iii) Inheritance

(iv) Polymorphism

(v) Abstraction

(vi) Encapsulation

3) Robust. Java makes an effort to eliminate error prone codes by emphasizing mainly on compile time error checking and runtime error checking but the main areas which Java improved were memory management and mishandled exceptions by introducing automatic garbage collector and exception handling. 

4) Platform independent. Unlike other programming languages such as C, C++ etc which are compiled into platform specific machines. Java is guaranteed to be write once, run anywhere any language. 

On compilation Java program is compiled into byte code. This byte code is platform independent and can be run on any machine. This byte code formate also provide security. Any machine with Java run time environment can run Java program. 

Java program — [Byte code] - {Linux OS

                                                       Windows OS

                                                        Mac OS}

5) Secure. When it come to security, Java is always to first choice. With Java secure features it enable us to develop virus free, temper free system. Java program always runs in Java runtime environment with almost null interaction with system OS, hence, it is more secure. 

6) Multi threading. Java multi threading feature make it possible to write program that can do many tasks simultaneously. Benefits of multi threading is that is utilizes same memory and other resources to execute multi threads at the same time, like while typing, grammatical errors and checked along. 

7) Architectural neutral. Compiler generates byte codes, which have nothing to do with a particular computer architecture. Hence, a  java program is easy to interpret on any machine. 

8) Portable. Java byte code can be carried to any platform. No implementation dependent features. Everything related to storage in predefined

    Example- size of primitive data types. 

9) High performance. Java is an interpreted language, so it will never be as a compiled language like C or C++. But Java enables high performance with the use of just-in -time compiler. 

10) Distributed. Java is also a distributed language. Programs can be designed to run on computer networks. Java has a special class library for communicating using TCP/IP protocols. Creating network connections is very much easy in Java as compared to C/C++.

Java keywords:

There are 50 keywords in Java i.e.

abstruct byte class do extends for import long private short switch throws volatile

assert case const double final goto instance of native protected static synchronized transient while

boolean catch continue else finally if int new public strictfp this try

break char default enum float implement interface package return super throw void

Data types in java:

In java there are two types of data types-

1. Primitive
2.  Non primitive

1. Primitive data types-

• Numeric
• Non numeric

• Numeric - 

         (i) integer- byte, short, int, long

         (ii) floating point - float, double

• Non numeric - 

         (i) character, boolean 

2. Non primitive data types-

• class, array, interface

     

Inheritance

Inheritance:

It is a important feature implemented OOP system by which one class can get all of the properties from another one class along with the same. It can take some new property of its own. 

Syntax:

  class     derived class name: visibility mode     base class name. 

  {

     - - - - - - -

     - - - - - - - 

     - - - - - - -

 }

Types of inheritance:

Now class can be derived from an existing class then the new derived class is called derived class or sub-class and the existing class is called base class or super class. And it is said that the sub class inherits from the base class. It is may take place in many terms. Such as:

1. Single inheritance

2. Multiple inheritance

3. Hierarchical inheritance

4. Multi-level inheritance

5. Hybrid inheritance

1. Single inheritance- When a subclass inheritance from one base class, it is known as single inheritance. 

         X

         ↓

         Y

2. Multiple inheritance- When a subclass inherits from multiple base classes, it is known as multiple inheritance. 

        X     Y

         ↘  ↙

            Z

3. Hierarchical inheritance- When many subclasses inherits from a single base class, it is known as hierarchical inheritance. 

           W

         ↙↓↘

      X   Y   Z

4. Multilevel inheritance- The translative nature of inheritance is reflected by this form of inheritance. When a subclass inherits from a class that itself inherits from another class, it is known as multilevel inheritance. 

           X

           ↓

           Y

           ↓

           Z

5. Hybrid inheritance- When a subclass inherits from multiple base classes and all of the its base classes inherits from a single base class this form of inheritance is known as hybrid inheritance. 

   In otherwords, The combination of multiple inheritance and hierarchical inheritance is known as hybrid inheritance. 

             W

           ↙ ↘

          X     Y

          ↘  ↙

             Z

Constructor in C++

Constructor in C++

 Constructor is a special member function whose task is to initialise the object of its class. It is special because its name is same as the class name. It is called constructor because it construct the value of data members of the class. Constructor is having no return type. 

Types of Constructor:

There are 3 types of constructor in C++

1. Default Constructor: 

Default constructor is the one which does not accept any value. It is mainly used to initialize the instance variable with the default values. It can also be used for performing some useful task on object creation. A default constructor is invoked implicity by the compiler if there is no constructor defined in the class. 

2. Parameterized Constructor:

Parameterized constructor is the one which can initialize the instance variables with the given values. In otherwords, the constructor which can accept the arguments are called parameterized constructor. 

3. Copy Constructor:

The constructor which is initializes an object using another object of same class is called copy constructor. 

What is C++ ?

 C++ programming :

C++ is a general purpose object oriented programming (oop) language developed by Bjarne Stroustrup. 

C++ was developed at AT & T's Bell laboratories of USA in early 1980's. It was expended version of 'C'. 

Difference between C and C++ :

The major difference between C and C++ is that 'C' is a procedural programming language and does not support class and object, while C++ is a combination of both procedural and object oriented programming language; therefore C++ can be called a hybrid language. 

Data types used in C++ :

Data types in C++ can be classified under various categories as shown below

c++ data types -

1) User-defined type-

     structure, union, class, enumeration

2) Built in type-

     (i)  integral - int, char

     (ii) void

     (iii) floating type - float, double

3) Derived type -

     array, function, pointer, reference

Operators used in C++ :

1) All 'C' operators are valid in C++ also. 

2) In addition C++ introduce some new operators also. 

Stream operators-

     :: ( scope resolution operator) 

     : (colon operator) 

    ・(class member access operator) 

     endl (line feed operator) 

     setus (field with operator) 

Stream operators -

     << and >> (stream operators) in C++ provide alternative to using printf (), scanf (), and other functions defined in stdio.h.

C in function. The C in function takes input from user. 

Syntax- Cin >> variable name ;

(The >> operator is thrown as the extraction or get from operator. It extracts or takes a value from keyboard. 

C out function. The C out function display output on the screen. 

Syntax- Cout << "message" << variable name<< endl ;

(The << operator is thrown as the insertion put the operator. It insert or send the contents of the variable. 

Program-

// write a C++ program to enter any two numbers and find out their sum and average

# include < iostream.h >

# include < conio.h >

void main () 

{

     into x, y ;

     float sum, average ;

     Cout << " enter the value of x =  " << x <<         endl ;

     Cin >> x ;

     Cout << " enter the value of y =  " << y <<         endl ;

     Cin >> y ;

     sum = x + y ;

     average = sum/2 ;

     Cout << " sum =  " << sum << endl ;

     Cout << " average =  " << average << endl ;

     getch () ;

}

Output :

      enter the value of x = 10

      enter the value of y = 6

      sum = 10 + 6 = 16

      average = 10 + 6 / 2 = 8

C++ is a general purpose object-oriented programming (OOP) language developed by Bjarne stroustrup. C++ was developed at AT & T's bell laboratories of U.S.A in early 1980's. C++ was expended version of C.

 C++ keywords:

asm              double           new             switch

auto             else                operator    template

break           enum             private        this

case             extern           protected     throw

catch           float              public            try  

char             for                 register       typedof  

class            friend            return           union

const           goto              short           unsigned

continue     if                   signed            virtual

default        inline            sizeof             void

delete          int                  static            volatile 

do               long                struct             while 

Added by ANSI C++

bool const_cast dynamic_cast explicit

export false mutable namespace

reinterpret_cast static_cast true typeid

typename using

Vertical Button Bar in TALLY. ERP 9

  The buttons are designed to make the work easier and faster, they very from one screen to another based on the screen functionality. They appear on the right hand side of the Tally. ERP 9 screen and inactive buttons are greyed out. You can either click these buttons or press the shortcut keys to access the relevant screen

The following are some of the buttons and their functions:

F1: Select Cmp: Display list of the all companies available in the database of tally. It displays the list of companies screen where you can select the desired company in which you want to work. 

F1: Shut Cmp: Allows you to unload (disable) a company. In case you again want to work on the same company, you can load (enable) in it by pressing F1. 

F2: Date: Allows you to set the date. 

F2: period: Allows you to set the starting and ending dates of financial year of a company. 

F3: Company: this button helps you to switch from one active company to another active company. 

F3: Company Info: Select this option by pressing ALT and F3 keys simultaneously. This involkes the company info. menu. 

F4: Connect: It allow you to connect with Tally. Net. 

F11: Features: It displays the company features menu which you can use to set option for accounting, inventory, statutory & taxation, etc. 

F12: Configure: this button display the configuration menu which you can use to configure currency, printing, data, vouchers, invoices, etc. 

Minimise Button: The Minimise Button performs the standard Windows Operating System function, allowing you to minimize Tally. ERP 9 and work on other applications. To restore Tally. ERP 9, click on the Tally. ERP 9 icon on the taskbar. 

Close Button: The Close Button in the upper right corner functions similar to the use of Esc in Tally. ERP 9. It brings you to back to the Gateway of Tally. ERP 9 from any screen.