basic defination & its uses.

#include:- It is a preprocessor complier or directive.
iostream:- It use for input & output stream.
    .h:-        It is header file. A file containing CPP tokens to set the particular model resolution and configuration named with a ".h" suffix {example= include.h}.
conio:-      It used for console input & output.
complier:-   A program that translates a high-level language, such as BASIC, into machine language. A compiler is a computer program (or set of programs) that transforms source code written in a computer language(thesource language) into another computer language (the target language, often having a binary form known as object code). The most common reason for wanting to transform source code is to create an executable program.
main():- The main program start, with keyword main(), each program must have a main() function.
curly Braces{}:- All the coding is include in the body of the main program in the curly braces{} & } end the coding for the program.
getch():- getch is used for get the result or output.

largest number from the given number program

#include
#include
void main()
{
int a,b,c,large;
cout<<"enter three numbers:";
cin>>a>>b>>c;
large=a>b?(a>c?a:c):(b>c?b:c);
cout<<"the largest of three number is"<<<"/n";
getch();
}

Practice problem 2

Ques) :- Find the potential difference between points F & C of the electric circuit shown in figure.

Solution :- V(F) – V(C) = - 4/3 volt.

                     Here negative sign shows that V(F) < V(C).

[ hints :- To find potential difference between any two points of a circuit you have to reach from one point to other via any path of the circuit.

                   For sloving easily Always choose a path which have least number of resistors preferably a path which has no resistance. ]

Capacitance of a spherical conductor.

     v Capacitance of a spherical conductor.

 When a +ve charge q is given to a spherical conductor of radius R, the potential on it is, 

     From the above expression we find that,

                                               

Thus, capacitance of the spherical conductor is,

From this expression we can reach at the following conclusion. 

(1).

  

Which we have directly stated that C depends on the dimensions of the conductor.

If two conductors have radii R 1 & R 2 then,

(2).Earth is also a spherical conductor of radius 

 

m.    The capacity of earth is therefore,

                                             

C = 711  microF                       [ F= farad].

Practice Problem 1

Ques) :- Find currents in different branches of the electric circuit shown in figure.

solution:-  i 1 = 1A.
                 i 2 = 8/3A.
                 i 3 = -5/3A.

defination of junction & loop.

ques) :- what is junction?
 ans :- A junction in a circuit is a point where three or more conductors meet. It is also called nodes or branch.

  The above fig J is the junction point because at that point all the four conductors meet.


ques) :- what is loop?
 ans :-  A loop is a closed conducting path.

                         In the above fig. ABCD is closed conducting path that's we are called the above fig. is loop.     

Theory on kirchhoff's law.

Kirchhoff's laws :-

Many electric circuits cannot be reduced to simple series-parallel combinations. However, it is always possible to analyze such circuits by applying two rules. These rules are known as kirchhoff's rule.

Rules are as follows:-

1. kirchhoff's junction rule:- The algebric sum of the current into any junction is zero.

That is:-

 The junction rule is based on "conservation of electric charge" 

This law also tell:-  "The sum of all the currents directed towards a point in a circuit is equal to the sum of all the currents directed away from the point."

 applying the kirchhoff's junction rule in above fig, we find

i 1 +i 2 = i 3 + i 4.

sign convention:-      * sign is +ve if current direction towards junction .

                                    * sign is -ve if current direction away from junction.

2. Kirchhoff's loop rule:- The algebric sum of potential differences in any loop including those associated emf's  and those of resistive elements, must equal zero.

That is:-

The loop rule is based on" electrostatic field is conservative in nature".

now we study how to apply it:-

In case of only emf is given in circuit.

sign convention:- * sign is +ve when the direction of emf is from low to higher  potential.

                            *sign is -ve when the dirction of emf is from higher to lower potential.

[here lower potential means negative polarity side & higher potential means higher polarity side. The samll line of emf shows -ve polarity & the larger line of emf shows +ve polarity.]

In case when resistance and current are given.

sign convention:- *sign is positive when current is forward in direction of resistance.

                              *sign is negative when current is reverse in direction of resistance.

Now we apply both resistance & emf in a circuit & find equation for this circuit.

 The equation will be,

+ i R2 +E2 + i R1 +E1 = 0.

kirchhoff's law problem with solution.

UES_1) .Figure shows parts of a circuit. Calculate the power dissipated in 3ohm resistance. What is the potential difference   V(C) –  V(B)?

SOL :-

Applying kichhoff’s law junction law at E current in wire DE is 8A from D to E. Now further applying junction law at D. The current in 3ohm resistance will be 3  A to D.

Now the circuit is simplified.

Power dissipated in 3ohm resistance = i*i*R = 3*3*3

                                                                         =27 watt.

V(C) – V(B) : V(C) – 5*1 + 12 – 8*2 – 3 – 4*2= V(B)

                        V(C) – V(B) = 5 – 12 + 16 + 3 + 8

                                             = 20 volt.

( here <*> this symbol means multiply).