Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

Electrical Engineering SSC JE (Technical)

Electrical Engineering (EE) : Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

The document Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev is a part of the Electrical Engineering (EE) Course Electrical Engineering SSC JE (Technical).
All you need of Electrical Engineering (EE) at this link: Electrical Engineering (EE)

1. Electric Current
Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

The rate of flow of electric charge through any point of the circuit is called electric current. Its unit is ampere.


2. Coulomb's Law

According to this law, the force of attraction or repulsion between stationary point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them.

  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

Where K = 9 X    Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

 Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev Newton

  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev 
 

3. Electric Field 

It is the region surrounding an electric charge or group of charges, in which another charge experiences a force of attraction or repulsion.


4. Electric Lines of Forces

  • An electric lines of force field along which a free isolated unit positive charge moves.
  • Electric lines of force start from the positive charge and end to the negative charge.
  • No two lines of force can intersect each other because if they do so, then at the point of intersection two tangents can be drawn which would mean two directions of force at that point which is impossible.
  • These lines have a tendency to separate from each other in the direction perpendicular to their length.
  • Lines of force of uniform field are parallel.
  • Lines of force leaves the surface of the conductor normally.


5. Electric Flux

  • It is defined as that total number of lines of force passing normally through a curved surface placed in the field or the dot product of Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev and normal.
    Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev 1 unit = Volt-meter  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


6. Ohm's Law 

  • According to this law if there is no charge the physical state of conductor (Such as temp.) then the current flowing through the conductor is directly proportional to the voltage applied i, e.
    I α V .
    I =  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev
  • A graph between applied voltage and current is a straight line shows that it follows ohm's law.
  • Ohm's law is valid for metallic conductors only.


7. Resistance 

It is property of:  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

ρ  = specific resistance or resistivity.

Note: The reciprocal of resistivity is called conductivity.

  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev   (Ohm – m)–1 = mho/meter.


Colour Code for Resistances:

  • These resistances are usually carbon resistances and whose code is used to indicate the value of resistance. 
  • A carbon resistance has usually 4 concentric rings or bands A, B, C, D of different colours.
    Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev
  • The colour of first two bands A and B indicate the 1st two significant figures of resistance in ohms & those of 3rd band C indicate the decimal multiplies. The 4th band D (Which is either silver or gold) tells the tolerance. 
  • Sometimes only 3 colours band is there (A, B and C).

NOTE: B. ROY Great Britain Very Good Wife.               Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


8. Electric Potential 

  • The electric potential at a point in an electric field is the ratio of the work done in bringing a test charge from infinity to that point to the magnitude of the test change. 
  • If the work done in moving a test charge q0 from infinity to that point against the field is W, then
      Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


9. Potential Gradient

Rate of charge of potential w.r.t distance in called potential gradient.


10. Electric Potential Energy

  • The electric potential energy of a system of charges is the work that has to be done in bringing these charges from infinity to near each other to form the system.
  • The potential energy of a system of charges q1 and q2 separated by a distance 'r' is
    Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


11. Capacitor

An element in which energy is stored in the form of an electrostatic field is called a capacitor.

Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


12. Capacitance

Defined as the ratio of charge given to the plate of the capacitor to the potential difference produced between the plate.
Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev
Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev Area of Plane

D → Distance between the planes.

0 = 8.85 x 10-12 

0 = Permittivitty of free space.

Unit – c2N–1 M–2

For a capacitor, v ∝ q

Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


Energy stored in a capacitor:

Energy(E) =  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

=   Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

= C.  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


13. Inductor

It is an element in which energy is stored in the form of an electromagnetic field (Unit  → Henry.)  

Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


Energy stored in Inductor:

Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

= L.  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev
 

14. Inductance

Inductance results from the fact that a flow of current produces a magnetic field, according to magnetic field along tends to induce a voltage (or current) in a wire according to Faraday's law.

Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

(i) For RL Load :

V=Vm sin wt

Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

 Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

show I lags by 90º R-L Load phasor :-

 Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev
Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRevChapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


(ii) For RC Load:

Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

Shows I leads by 90º


(iii) For RC phases:

  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev
Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


(iv) For RLC Load:

Case 1: |VL| >  |Vc|
Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

  Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev

 

Case 2: |VL| <  |Vc|

Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev


Chapter 1 Basic Electrical - Notes, Circuit Theory, Electrical Engineering Electrical Engineering (EE) Notes | EduRev
 

Case 3: |VL| =  |Vc|

V = VR

Ø = 0

CosØ = 1(UPF)

Note:- Reactive power is consumed by energy storing demands.

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