Inscribed And Circumscribed Circle in a Triangle

Circle Inscribed In a Triangle

    It is a circle inside a triangle that touches all sides of it. Formula to find the area of the circle is

Radius = (2√(k(k-a)(k-b)(k-c)))/a+b+c

Where k=(a+b+c)/2

            a,b,c= three sides of the triangle

Area of the inscribed is = pi*radius^2

Circumcircle Of A Triangle

It is a circle that touches all the vertices of a triangle. The formula to find the area of the circle

 Radius = abc/4At 

    Where abc are the three sides of the triangle and

                At is the area of the triangle

DC Machines

Things to remember in a DC Machine

1. EMF equation of a DC motor or generator = (fi*Z*N*P)/60A

Where, fi = flux/pole
             Z= number of armature conductors
             N= Speed in RPM
             P= Number of poles
             A= number of parallel paths i.e A=2 in case of wave winding and A=P(number of poles) in                        case of lap winding
   
     2. Speed = 120F/P

Where f = frequency and P  = number of poles

Famous Books And Their Authors

Famous Books And Their Authors

1. Three decades in parliament - A.B. Vajpayee
2. 
   

All Laws Used in Electrical Engineering

Kirchoff's Current law

 The sum of all currents flowing into a node is zero. Or conversely, the sum of all currents leaving a node must be zero or the sum of incoming currents at a node is equal to the sum of outgoing currents. This is kirchoff's first law.

Kirchoff's Voltage law

 The sum of all voltage sources and voltage drops in a circuit is zero. This is kirchoff's second law.

Ohm's law

A law stating that the current in a circuit is directly proportional to the voltage and inversely proportional to the resistance.

I=V/R

Fleming's Left Hand Rule

when an current carrying conductor is placed inside a magnetic field, a force acts on the conductor, in a direction perpendicular to both the directions of the current and the magnetic field. Thumb indicates direction of force, forefinger indicates direction of magnetic field and middle finger indicates the direction of current.

Fleming's Right Hand Rule

 When the conductor moves in a magnetic field the induced current is perpendicular to the motion of the conductor and the magnetic field. Thumb indicates the motion of the conductor, forefinger indicates the direction of magnetic field and the middle finger indicates the direction of current flow.

Ampere's rule

  Ampere's law is used to find the direction of lines of force around a wire carrying current.

Gauss law

The total of the electric flux out of a closed surface is equal to the charge enclosed divided by the permittivity. The electric flux through an area is defined as the electric field multiplied by the area of the surface projected in a plane perpendicular to the field.

Coulomb's first law

Like charges attract each other whereas unlike charges repel each other.

Coulomb's Second law

The force exerted between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.

Lenz's Law

Lenz's law states that when an emf is generated by change in magnetic flux the polarity of the induced emf is such that it produces a current which opposes the change which produces it. 

Types Of Magnets Or Magnetism

Paramagnet or Paramagnetism

       Paramagnet is a temporary magnet. Paramagnetism is a form of magnetism whereby certain materials are attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field.

Ferromagnet or Ferromagnetism

     Ferromagnet is a permanent magnet.Ferromagnetism is the theory which explains how materials become magnets. Ferromagnetism is the basic mechanism by which certain materials (such as iron) form permanent magnets, or are attracted to magnets.

Diamagnet or Diamagnetism

      A diamagnet is not a permanent magnet. In most materials diamagnetism is a weak effect, but a superconductor repels the magnetic field entirely, apart from a thin layer at the surface. Diamagnetic materials create an induced magnetic field in a direction opposite to the applied magnetic field.

RLC Circuit

1. Formula for bandwidth in an RLC circuit
Ans. Bandwidth BW=R/2piL
          where R is the resistance, pi is 3.14, L is the inductance