C program to find second largest element

#include<stdio.h>
int main()
{
int a,b,temp,t;
scanf("%d%d",&a,&b);
if(a<b)
{
 t=a;
 a=b;
 b=t;
}
scanf("%d",&temp);
while(temp!=-1)
{
 if(temp<b)
 scanf("%d",&temp);
 else if(temp>b)
 {
 b=temp;
 scanf("%d",&temp);
 }
 if(a<b)
 {
 t=a;
 a=b;
 b=t;
 }
}
printf("%d",b);
return 0;
}

Pythagorean triples

#include<stdio.h>
int main()
{
int a,b,c;
scanf("%d %d %d",&a,&b,&c);
if((a*a)==(b*b)+(c*c))
printf("yes");
else if((b*b)==(c*c)+(a*a))
printf("yes");
else if((c*c)==(a*a)+(b*b))
printf("yes");
else
 printf("no");
return 0;
}

How three phase system reduces the copper loss

Consider a 5KW load.If a single phase system it then we require 2 wires,one carrying the current towards the load and other carrying current away from the load. Assume that the applied voltage is 100V  then the current is 30A.if we see the copper losses in it(if resistance of each wire is 1 ohm) the Total copper loss is 1800 watts (900+900).
Now consider a three phase balanced supply.It has three wires each carrying 10 amps current then calculate the losses which are less when compared to that of single phase.

STRUCTURE OF AN ATOM

We know that the size of atom is so small that it can not be seen with the most powerful microscope 🔬.

Then a doubt arises in our mind,how did scientists determined its structure?

They adopted a alternative method in which they will first studied the properties of an atom and on that basis they have determined its possible structure.

So always keep in mind that structure of an atom is determined on the basis of its properties but not by seeing it.

Retardation test of DC SHUNT MACHINE:

Retardation test (or) running 🏃 down test of dc machine
This method is used to find the constant losses(friction + windage + iron losses)

This is also a noload test. We can calculate the efficiency of a dc machine by knowing the armature amd shunt copper losses at a given load.

Consider a DC SHUNT MOTOR running at noload.
If the supply to the
                                   1.Armature is cut off 📴 and the supply to the field remains same then the KINETIC ENERGY ⚡ is used to overcome (friction + Windage +Field copper ) no load losses
                                   2.Armature as well as field to the field is cut off then the KINETIC ENERGY ⚡ is Used to overcome only the friction losses  + Windage losses.  (their will be no field copper loss because in second case their is no supply to the field)

How to conduct it:
It is very easy to conduct it we have to remove the supply and calculate the rate at which the speed falls.

Losses can be calculated by using formula (derivation):

     Since kinetic energy ⚡ is used to overcome losses:

                  W=(d(Iw^2)/2dt)
where     w(omega)= 2πN/60  in rad/sec
         
On differentiation we get
                   W= 2Iw (dw/dt)
Now substitute w= 2πN/60.
We get
                W= (((2π)÷(60))^2)(IN(dN/dt))

Where
          I=Moment of inertia of armature.
          N=speed of armature in rpm.

Accordingly  if the supply to the armature is cut off and supply to field is not cut off then 'W' indicates friction +windage+Field copper losses.

If supply to both armature as well as the field is Cut Off Then 'W' indicates only Friction + Windage Losses.

To find I:
                But it is difficult to find the moment of inertia of Armature i.e 'I' . It can be easily found by conducting another experiment

Firstly,the retardation test is conducted and dN/dt1 is noted

Secondly,the shaft of the motor is keyed to the flywheel 🎡 of known moment of inertia I1 and the time for the fall of same speed is noted i.e dN/dt2

Since in both cases same motor is used so losses are equal

Losses in case1:
W= (((2π)÷(60))^2)(IN(dN/dt1))

Losses in case2:
W=(((2π)÷(60))^2)((I+I1)N(dN/dt2))

N=speed in rpm
I=Moment of inertia of armature.
I1=Moment of inertia of flywheel
Equating above two equations we get I value if I1 value is known

Hence by retardation test we can calculate losses.

Worlds largest electricity generating station

The worlds largest electricity generating station is located in china.It is a hydro electric power plant which is across the dam THREE GORGES DAM. Its generating capacity in watts is 22500.
For generating that much amount of power it employs 32 Francis turbines each of a capacity of 700 MWand two 50 MW turbines.
32*700=22400 MW
02*50 =     100 MW
Total. =22500 MW

Father of battery

An 18th century scientist named ALESSANDRO VOLTA developed a voltaic pile which was later developed into battery 🔋.VOLTAGE is named after him.