# Definitions of Electrical Engineering

Electrical engineering is built up of number of basic definitions and concepts. Without understanding these terms, you can’t be able to learn electrical engineering.

So, here I am sharing some of the basic definition and terms of Electrical Engineering for your information.

## Basic Definitions and terms of Electrical Engineering

### Electric voltage

The potential difference between two points of a conductor is called electric voltage and is represented by a symbol V. It is also called as electrical potential or electrical pressure. It can also be defined as the work done by a body to move the charge from one place to another.

For example, if the amount of work done is 2 joules to move a charge from one place to another, then there exists an electric potential of 2 voltage between the two points, where joule is the unit used to measure the amount of work done or energy.

### Electric Current

The flow of electrons in a conductor in known as electric current and is represented by a symbol I. Conventionally, the direction of current flows from positive terminal to negative terminal. The unit of current is ampere(A) or coulomb per second.

If 1 coulomb of charge passes through the conductor in one second, then the flow of charge or current is said to be 1 ampere. It is expressed as

The relation between voltage and current is given by Ohm’s law.

### Electric Power

Power is defined as work done per unit time. If force *F* acts on a body for *t* seconds and so the body moves through a distance of *d* metre along a straight line, then the work done is given by *F x d* joules.

In electrical terms, power is defined as the rate at which the electrical energy is transferred by an electrical circuit.

If the current flowing between two points in a conductor is *i* and the voltage is *v*, then power is defined as the product of voltage and current.

### Electric Circuit

The closed path in which the electrons or current flow from a voltage or current source is called an electric circuit.

### Independent voltage and current source

If the voltage source is independent of the current flowing through the circuit, then it is called an independent voltage source.

It the current source is independent of the voltage across it, then the source is said to be an independent current source.

### Resistor

The resistor is a passive circuit element that dissipates the electrical energy as heat when the current passes through it. The resistor provides resistance in an electrical circuit.

Resistance is the property of the circuit element which offers opposition to the flow of current through the conductor. The resistance of a resistor depends on the material of which the conductor is made.

The resistance *R* of a conductor is proportional to its length *l* and inversely proportional to its cross-sectional area *a*. It is given by,

Where, ρ represents the resistivity of the material. The unit of resistance is Ω and the unit of resistivity is Ωm.

The inverse of resistance is called **conductance**(G) and the inverse of resistivity is called **conductivity**(σ) or specific conductance. The unit of conductance is ℧.

### Inductor

An inductor stores the electrical energy in magnetic field by virtue of current through it. Inductors are made of number of turns of thin wire wound on the magnetic core. The voltage across the inductor is proportional to the rate of change of current through it.

### Eddy Current Loss

When an alternating magnetic field is applied to a magnetic material, an emf is induced in the material itself according to Faraday’s Law of Electromagnetic induction. Since the magnetic material is a conducting material, these EMFs circulates currents within the body of the material. These circulating currents are called Eddy Currents. As these currents are not responsible for doing any useful work, it produces a loss (I^{2}R loss) in the magnetic material known as an Eddy Current Loss.

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