Basic Electrical Concepts

# Basic Electrical Concepts | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE) PDF Download

 Table of contents 1. Electric Current 2. Coulomb's Law 3. Electric Field 4. Electric Lines of Forces 5. Electric Flux 6. Ohm's Law 7. Resistance 9. Potential Gradient 10. Electric Potential Energy 11. Capacitor 12. Capacitance 13. Inductor 14. Inductance

Some of the Basic Concepts include :

## 1. Electric Current

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.

Where K = 9 X

Newton

Question for Basic Electrical Concepts
Try yourself:What is the unit of electric current?

## 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.

Question for Basic Electrical Concepts
Try yourself:
What is the purpose of electric lines of force?

## 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  and normal.
1 unit = Volt-meter

## 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 =
• 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:

ρ  = specific resistance or resistivity.

Note: The reciprocal of resistivity is called conductivity.

(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.
• 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.

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

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

## 11. Capacitor

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

Practical Capacitor

Capacitor Circuit diagram

## 12. Capacitance

Defined as the ratio of charge given to the plate of the capacitor to the potential difference produced between the plate.

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

Energy(E) =

=

= C.

## 13. Inductor

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

Energy stored in Inductor:

= L.

Question for Basic Electrical Concepts
Try yourself:What is the unit of electric flux?

## 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.

V=Vm sin wt

show I lags by 90º R-L Load phasor :-

(iii) For RC phases:

Case 1: |VL| >  |Vc|

Case 2: |VL| <  |Vc|

Case 3: |VL| =  |Vc|

V = VR

Ø = 0

CosØ = 1(UPF)

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

The document Basic Electrical Concepts | Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE) is a part of the Electrical Engineering (EE) Course Electrical Engineering SSC JE (Technical).
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## FAQs on Basic Electrical Concepts - Electrical Engineering SSC JE (Technical) - Electrical Engineering (EE)

 1. What are the basic concepts of electrical engineering?
Ans. Electrical engineering deals with the study and application of electricity, electronics, and electromagnetism. It includes concepts such as voltage, current, resistance, circuits, and electromagnetic fields.
 2. What is the difference between AC and DC electricity?
Ans. AC (alternating current) electricity changes direction periodically, while DC (direct current) electricity flows in one direction continuously. AC is commonly used in households, while DC is used in batteries and electronic devices.
 3. What is Ohm's Law and how is it used in electrical engineering?
Ans. Ohm's Law states that the current flowing through a conductor is directly proportional to the voltage across it and inversely proportional to its resistance. It is used to calculate current, voltage, and resistance in electrical circuits.
 4. What are the different types of electrical circuits?
Ans. There are two main types of electrical circuits: series circuits, where components are connected in a single path, and parallel circuits, where components are connected in multiple paths. Combination circuits consist of a mix of series and parallel components.
 5. How is power calculated in electrical engineering?
Ans. Power in an electrical circuit is calculated using the formula P = VI, where P is power in watts, V is voltage in volts, and I is current in amperes. This formula can also be used in conjunction with Ohm's Law to calculate power in terms of voltage and resistance or current and resistance.

## Electrical Engineering SSC JE (Technical)

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