Nature of Electricity
Drift Velocity & Electron Mobility
Heating Effect of Electric Current
Static Electric Field
Magnetic field of current carrying conductor
Magnetic Flux Density
• Wire Wound Resistor
Resistance Variation with Temperature
Temperature Coefficient of Resistance
Resistances in Series and Parallel
Theory of Electrical Potential
Capacitor and Capacitance
What is Capacitor?
What is Inductor?
Single Phase Power
Single Phase Power Equations
Three Phase Power
There is a relation between seller and consumer, consumer buys product from the seller. Except of this connection of selling and buying there is another relation which is of donor and acceptor. Now from the same point of view we can divide electric charges. We know there are two types of charges present in the nature (i) positive and (ii) negative charge. In positive charge there is mainly deficiency of electrons and in negative charge there are excess electrons. Now, we can simply understand the concepts of charges from a very basic example. Take a dry comb, comb your hair (which should be dry also) two to three times, now take that comb near tiny piece of papers, you will see that the papers are getting attracted by the comb. This is the very basic example of electric charge and static electric field. Due to friction there is movement of electrons between comb and hair, so one of them gets positively charged another one negatively charged and as the paper is neutral (i.e. not charged) they get attracted by the comb. So, we can see that there is an attraction force works between charged particle and neutral particle, it has been seen further that there is repulsion between two same charged particles and attraction between two differently or opposite charged particle. This happens due to the field created around a particle. This can be understood if we imagine or glowing bulb, the bulb can be taken as the charge and the visible light is nothing but static electric field, the characteristic of field is similar to the light in the sense that the intensity of the field is greater near the source and it fades as we move further from the source. Now from another point of view we can say that static electric field is nothing but an intense space, in terms of power where work is done or needed to be done upon in presence of an electrically charged particle depending on the nature of the charged particle.
A positive charge lacks electrons, where as a negative charge has excess electrons. What about the phenomenon of attraction of a neutral particle by a charged particle because we can understand the phenomenon of attraction and repulsion between oppositely charged particles and same charged particles, but how neutrally charged particles get attracted by charged particles. This can be explained by electrostatic induction. The word induction itself explains a lot, it means action which is not the result of direct contact. To explain the above explained phenomenon, we can say that when a neutral body is brought near the charged body, opposite charge is induced in the neutrally charged body near to the charged body and same charge on the opposite side. We can understand the phenomenon more accurately by a diagram.
From the diagram the very basic operation of electrostatic induction can be understood. Opposite charge is induced near the charge and similar charge is induced further from the charge. In a more easier way we can say that this phenomenon is actually the redistribution of electric charges inside a matter in a more organised manner and the orientation depends upon the inducing charge.
Electric Field Strength
We discussed earlier, what is electric field. Now in this article we will know about electric field strength. Mainly this term electric field strength is used when two charged particles are kept near to each other. During that time electric field due to both the charges create a resistant electric field and the strength of that field can be determined by Coulomb’s law. Now we need to know, what is Coulomb’s law ?
This law states that the force between two charges
(i) is directly proportional to the product of the charges,
(ii) inversely proportional to the square of the distance between them and
(iii)depends on the nature of the medium surrounding the charges.
To show the relation mathematically among force ‘F’ between two point charges leaving charge ‘Q1’ and Q2 and placed at a distance ‘d’ from each other is given by
Where K is any constant, in SI system the force between two charges is given by
Here εo is the permittivity of vacuum = 8.854 x 10 - 12 F/m and εr is the relative permittivity of the surrounding medium. Depending on the force, the electric field strength is determined and expressed in v/m (volts per meter). This force is a vector quantity and has direction. And finally it can be said that any charged particle has an electric field around itself and the strength of this field depends on the charge of the particle.
Electric Field Intensity
Intensity means the magnitude or amount. Now field intensity similarly means the magnitude of the strength of the field. Basically electric field intensity is considered for point charges. If we give the definition of this term it would be like, the force experienced by an unit charge if placed at a distance ‘d’ from a charge ‘Q’. And This force exerted on the unit charge can be determined by the Coulomb’s law which is like
The electric field intensity is vector quantity(i.e. it both have magnitude and direction) and is devoted by ‘E’ and magnitude is given by
The intensity is felt more when the unit charge is placed at the nearest of the charge and it is lightest when at infinite distance.